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Enterasys Vertical Horizon VH-2402-L3, Management Manual

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9033691-01 

VH-2402-L3 Management Guide  145 

Layer 3-Based VLANs 

Layer 3-based VLANs use network-layer addresses (subnet 
address for TCP/IP) to determine VLAN membership.  These 
VLANs are based on layer 3 information, but this does not 
constitute a ‘routing’ function. 

The VH-2402-L3 allows an IP subnet to be configured for 
each 802.1Q VLAN that exists on the switch

. 

Even though a switch inspects a packet’s IP address to 
determine VLAN membership, no route calculation is 
performed, the RIP protocol is not employed, and packets 
traversing the switch are bridged using the Spanning Tree 
algorithm. 

A switch that implements layer 3 (or ‘subnet’) VLANs without 
performing any routing function between these VLANs is 
referred to as performing ‘IP Switching’. 

Internet Protocols 

This is a brief introduction to the suite of Internet Protocols 
frequently referred to as TCP/IP.  It is intended to give the 
reader a reasonable understanding of the available facilities 
and some familiarity with terminology.  It is not intended to 
be a complete description. 

Protocol Layering 

The Internet Protocol (IP) divides the tasks necessary to 
route and forward packets across networks by using a 
layered approach.  Each layer has clearly defined tasks, 
protocol, and interfaces for communicating with adjacent 
layers, but the exact way these tasks are accomplished is 
left to individual software designers.  The Open Systems 
Interconnect (OSI) seven-layer model has been adopted as 
the reference for the description of modern networking, 
including the Internet.  

Summary of Contents for Vertical Horizon VH-2402-L3

Page 1: ...VERTICAL HORIZON VH 2402 L3 FAST ETHERNET SWITCH MANAGEMENT GUIDE 9033691 01 ...

Page 2: ...ii VH 2402 L3 Management Guide ...

Page 3: ...LUDING BUT NOT LIMITED TO LOST PROFITS ARISING OUT OF OR RELATED TO THIS DOCUMENT WEB SITE OR THE INFORMATION CONTAINED IN THEM EVEN IF ENTERASYS NETWORKS HAS BEEN ADVISED OF KNEW OF OR SHOULD HAVE KNOWN OF THE POSSIBILITY OF SUCH DAMAGES Enterasys Networks Inc 500 Spaulding Turnpike Portsmouth NH 03801 2002 Enterasys Networks Inc 0 All Rights Reserved Printed in the United States of America Order...

Page 4: ... or Deleting User Accounts 13 Viewing Current User Accounts 14 Deleting a User Account 15 Basic Setup 16 Switch Information 16 Configuring the Switch s IP Address 17 Remote Management Setup 20 Setting Up Trap Receivers 21 Configure Ports 23 Serial Port Settings 24 Switch Operation Mode 26 Changing the Switch Operation Mode 27 Menu Changes with Switch Operating Mode 28 Screen Hierarchy 30 Layer 2 S...

Page 5: ...g 79 Switch Utilities 82 Layer 2 Switch Utilities 82 Updating Firmware 82 Downloading a Configuration File 83 Uploading a Settings File 84 Uploading a History Log File 85 Testing Connectivity with Ping 86 Layer 3 Utilities 86 BOOTP DHCP Relay 86 DNS Relay 89 Network Monitoring 91 Layer 2 Network Monitoring 91 Port Utilization 92 Port Error Statistics 93 Port Packet Analysis Table 96 MAC Address Fo...

Page 6: ...128 Notes About VLANs on the VH 2402 L3 128 IEEE 802 1Q VLANs 129 802 1Q VLAN Packet Forwarding 129 802 1Q VLAN Tags 130 Port VLAN ID 132 Tagging and Untagging 133 Ingress Filtering 134 VLANs in Layer 2 Only Mode 135 Layer 3 Based VLANs 135 IP Addressing and Subnetting 136 Definitions 136 IP Addresses 136 Address Classes 138 Subnet Masking 139 Calculating the Number of Subnets and Nodes 140 Classl...

Page 7: ...lticast Routing Algorithms 168 Flooding 168 Multicast Spanning Trees 169 Reverse Path Broadcasting RPB 169 Reverse Path Multicasting RPM 170 Multicast Routing Protocols 171 Distance Vector Multicast Routing Protocol DVMRP 171 Routing Protocols 173 Protocol Independent Multicast Dense Mode 173 Routing Information Protocol RIP 173 RIP Version 1 Message Format 175 RIP 1 Message 176 RIP 1 Route Interp...

Page 8: ......

Page 9: ...d monitor its operation Switch configuration settings that are saved to non volatile RAM using Save Changes from the Main Menu are retained in the switch s memory and are reloaded when the switch is rebooted Before You Start The VH 2402 L3 supports a wide array of functions and gives great flexibility and increased network performance by eliminating the routing bottleneck between the WAN and the i...

Page 10: ...ated from the other subnets IP or MAC filtering can be used Also one or more VLANs on the Layer 3 switch can be configured without an IP subnet in which case these VLANs will function as a layer 2 VLAN and would require an external router to connect to the rest of the network 6 Develop a policy scheme Some subnets will have a greater need for multicasting bandwidth for example A policy is a mechan...

Page 11: ...ed on the switch to accommodate the IP subnets Finally the IP subnets can be assigned to the VLANs Assigning IP Interface Addresses and Subnet Masks to VLANs The VH 2402 L3 allows the assignment of IP subnets to individual VLANs Any VLAN configured on the switch that is not assigned an IP subnet will behave as a layer 2 VLAN and will not be capable of IP routing even if the switch is in IP Routing...

Page 12: ...Once you have set an IP address for your Switch you can use a TELNET program in VT 100 compatible terminal mode to access and control the Switch All of the screens are identical whether accessed from the console port or from a TELNET interface Console Usage Conventions The console interface makes use of the following conventions 1 Items in angle brackets can be toggled between several choices usin...

Page 13: ... enter the current configuration into the switch s Non volatile RAM First Time Connecting To The Switch The Switch supports user based security that can allow you to prevent unauthorized users from accessing the Switch or changing its settings This section explains how to log onto the Switch The passwords used to access the Switch are case sensitive therefore S is not the same as s When you first ...

Page 14: ...t Guide 9033691 01 Figure 1 1 Initial Console Screen The factory default Username is admin there is no factory default password Enter admin for the Username and leave the Password field blank to access the console initially ...

Page 15: ...and Access will be given to the main menu as shown below Figure 1 2 Main Menu The first user automatically gets Root privileges See Table 1 1 It is recommended to create at least one Root level user for the Switch Creating User Accounts To create a new user account highlight Setup User Accounts from the Main Menu and press Enter ...

Page 16: ...er then the Setup User Accounts menu appears 1 Toggle the Action field to Add using the space bar This will allow the addition of a new user The other options are Delete this allows the deletion of a user entry and Update this allows for changes to be made to an existing user entry 2 Enter the new user name assign an initial password and then confirm the new password Determine whether ...

Page 17: ... ram using the Save Changes command on the Main Menu Root User and Normal User Privileges There are three levels of user privileges Root and User and User Switch Configuration Privilege Management Root User User Configuration Yes Read Only Read Only Network Monitoring Yes Read Only Read Only Community Strings and Trap Stations Yes Read Only Read Only Update Firmware and Configuration Files Yes No ...

Page 18: ... L3 has two levels of memory normal RAM and non volatile or NV RAM Configuration changes are made effective by highlighting Apply and pressing Enter When this is done the settings will be immediately applied to the switching software in RAM and will immediately take effect Some settings though require you to restart the switch before they will take effect Restarting the switch erases all settings ...

Page 19: ...ve Changes Confirmation Screen Once the switch configuration settings have been saved to NV RAM they become the default settings for the switch These settings will be used every time the switch is rebooted Loading Factory Defaults Loading the factory defaults returns the switch s configuration to the factory default values This will clear all settings and restore them to their initial values liste...

Page 20: ...pear Highlight Yes and press Enter to reset the switch s NV RAM to the factory default settings This will erase any User Accounts and all other configuration settings you may have entered and return the switch to the state it was in when it was purchased Logging Onto The Switch Console To log in once you have created a registered user from the Login screen 1 Type in your username and press Enter 2...

Page 21: ... for the user account you wish to change and enter the Old Password for that user account 3 You can now modify the password or the privilege level for this user account 4 If the password is to be changed type in the New Password you have chosen and press enter Type in the same new password in the following field to verify that you have not mistyped it 5 If the privilege level is to be changed togg...

Page 22: ...ess to the console whether using the console port or via TELNET is controlled using a user name and password Up to eight user accounts can be created The console interface will not let you delete the current logged in user to prevent accidentally deleting all of the users with Root privilege Only users with the Root privilege can delete users To view the current user accounts Highlight Setup User ...

Page 23: ...ccount you want to delete You must enter the password for the account to be able to delete it 3 Highlight APPLY and press Enter to make the deletion of the selected user take effect 4 You must enter the configuration changes into the non volatile ram NV RAM using Save Changes from the Main Menu if you want the configuration to be used after a switch reboot Only users with Root privileges can delet...

Page 24: ...will help prepare the Switch user by describing the Switch Information IP Setup Remote Management Setup Configure Ports Serial Port Settings and Switch Settings menus Figure 1 12 Main Menu Switch Information Switch Information Highlight Switch Information from the Main Menu and press Enter ...

Page 25: ...f necessary You can also enter the name of the System its location and the name and telephone number of the System Administrator It is recommended that the person responsible for the maintenance of the network system that this Layer 3 switch is installed on be listed here Configuring the Switch s IP Address The BOOTP and DHCP Server options for assigning the switch an IP address and subnet mask ar...

Page 26: ...ted To set the switch s IP address Highlight IP Setup from the main menu and press Enter Figure 1 14 IP Setup Menu The switch s factory default IP address is 10 90 90 90 with a subnet mask of 255 0 0 0 and a default gateway of 0 0 0 0 To manually assign the switch s IP address subnet mask and default gateway address Highlight the IP Address 10 90 90 90 field and enter the appropriate IP address Hi...

Page 27: ...rst look for a BOOTP server to provide it with this information before using the default or previously entered settings DHCP The switch will send out a DHCP broadcast request when it is powered up The DHCP protocol allows IP addresses network masks and default gateways to be assigned by a DHCP server If this option is set the switch will first look for a DHCP server to provide it with this informa...

Page 28: ... ID VID from which a management station a computer will be allowed to manage the switch using TCP IP in band or over the network Management stations that are on VLANs other than the one entered in the Management VID ALL field will not be able to manage the switch in band unless their IP addresses are entered in the Management Station IP Addresses field Any VID that has been configured on the switc...

Page 29: ...0 0 fields contain all zeros 0 then any station with any IP address can access the switch to manage and configure it If there is one or more IP addresses entered in the IP Address 0 0 0 0 field then only stations with the IP addresses entered will be allowed to access the switch to manage or configure it Setting Up Trap Receivers This allows the switch to send traps messages about errors etc to ma...

Page 30: ... is configured to receive the SNMP traps from the switch The SNMP Community String is similar to a password in that stations that do not know the correct string cannot receive or request SNMP information from the switch The Status field can be toggled between Enabled and Disabled to enable or disable the receipt of SNMP traps by the listed management stations ...

Page 31: ...e port number appears Toggle the State Enabled field to either Enable or Disable a given port Toggle the Speed Duplex Auto field to either select the speed and duplex half duplex state of the port Auto auto negotiation between 10 and 100 Mbps devices full or half duplex The Auto setting allows the port to automatically determine the fastest settings the device the port is connected to can handle a...

Page 32: ...18 Serial Port Settings Screen Toggle the Serial port setting Console field to select either the Console or SLIP protocol The following fields can then be set Console Settings Parameter Description Baud Rate Displays the serial bit rate used to communicate with a management station The console baud rate is 9600 bits per second Data bits Displays the number of bits that make up a word when communic...

Page 33: ... Switch is restarted Applies only when the serial port is being used for out of band SLIP management it does not apply when the port is used for the console port Available speeds are 9600 19 200 and 38 400 bits per second The default setting is 9600 Interface Name This allows for the naming of the SLIP interface for easy reference Local IP Address This is an IP address assigned to the serial port ...

Page 34: ...source and destination MAC addresses only 802 1Q VLANs are supported and the switch is considered as a VLAN tag aware device 2 IP Routing Support IEEE 802 1Q VLANs the switching process is based upon the IP source and destination addresses if present If the IP addresses are not present the switching process is based upon the MAC addresses as in Layer 2 above 802 1Q VLANs are supported and the swit...

Page 35: ...Operation Mode To change the switch s operating mode Highlight Switch Settings on the main menu and press enter Figure 1 19 Switch Settings Screen Highlight Switch Operation Mode on the Switch Settings menu and press enter Figure 1 20 Switch Operation Mode Screen ...

Page 36: ... Confirmation Screen Type y and press Enter The switch will then save the changes made during the current session and reboot The switch must be rebooted to change the operation mode Menu Changes with Switch Operating Mode Once the switch is configured for IP Routing Layer 3 Switching and rebooted the Main Menu adds some functions compared to the Layer 2 Only mode These functions are reflected in a...

Page 37: ...9033691 01 VH 2402 L3 Management Guide 29 Figure 1 22 Main Menu Layer 2 Switching Mode Figure 1 23 Main Menu Layer 3 IP Routing Mode ...

Page 38: ...ilable only when the switch is in IP Routing mode These menus are shown in bold Main Menu Entry Sub Menus Switch Information Switch Information IP Setup IP Setup Remote Management Setup Remote Management Setup Switch Settings Switch Settings Switch Operation Mode Layer 2 Switch Settings Configure Ports Configure Ports Setup User Accounts Setup User Accounts Serial Port Settings Serial Port Setting...

Page 39: ...Changes Save Changes Confirmation Screen no sub menus Reboot Reboot Reboot Save Configuration Reboot Reboot Load Factory Default Configuration Reboot Load Factory Default Configuration Except IP Address Logout System Logout no sub menus Spanning Tree Configure Spanning Tree STP Group Configuration STP Port Settings Forwarding Forwarding Menu Setup Static Unicast MAC Forwarding Setup Static IP Rout...

Page 40: ...Snooping Layer 2 Only Set up IEEE 802 1Q Multicasting Forwarding IP Multicasting Settings Multicast Interface Configuration IGMP Interface Configuration IGMP Static Member Configuration DVMRP Interface Configuration PIM DM Interface Configuration Static Router Port Settings VLANs VLAN Menu Edit 802 1Q VLANs Configure 802 1Q Port Settings Port Trunking Port Trunking Layer 3 IP Networking Setup Laye...

Page 41: ... Switch GVRP Disabled Allows the Group VLAN Registration Protocol GVRP to be globally Enabled or Disabled on the switch Upper Threshold for Master Ports 128 Kpps This is the number of thousands Broadcast Multicast packets per second received by the switch on one of the Master Ports that will trigger the switch s reaction to a Broadcast Multicast storm Upper Threshold for Module Ports 128 Kpps This...

Page 42: ...y the switch s reaction to Multicast storms triggered at the threshold set above Advanced Setup Changing switch operation mode setting changes some of the menus and configuration options for the Advanced Setup of the switch The configuration data however is saved when the switch s operating mode is changed Configuring VLANs The switch allows the assignment of an IP interface to each VLAN in IP Rou...

Page 43: ...t Highlight VLANs from the Main Menu and press enter Figure 1 25 VLAN Menu To create an 802 1Q VLAN highlight Edit 802 1Q VLANs and press enter Figure 1 26 Edit 802 1Q VLANs Menu Parameter Description Action This field can be toggled using the space ...

Page 44: ... Egress Forbidden or Non member of a VLAN E Egress Member specifies the port as being a static member of the VLAN Egress Member Ports are ports that will be transmitting traffic for the VLAN These ports can be either tagged or untagged F Forbidden Non Member specifies the port as not being a member of the VLAN and that the port is forbidden from becoming a member of the VLAN dynamically Non Member...

Page 45: ...embership status in the Membership E F field The status indicators of the individual ports can be entered directly from the keyboard or toggled using the space bar Moving between the status indicators of the individual ports is accomplished using the arrow keys To set the 802 1Q VLAN membership status of a port To enter the 802 1Q VLAN status for a port highlight the first field of Membership E F ...

Page 46: ...tions deletions effective for the current session To make enter the IP Interfaces into Non volatile RAM highlight Save Changes from the Main Menu and press enter In the following example screen the VLAN evilJulius VID 2 has been added Ports 1 2 12 14 17 25 and 26 are Egress ports static members of evilJulius Ports 5 6 and 7 are Forbidden ports non members and are not allowed to join the VLAN evilJ...

Page 47: ...Menu Highlight Configure 802 1Q Port Settings and press enter Figure 1 29 Configure 802 1Q Port Settings Parameter Description Configure Port from to This allows the entry of a contiguous range of port numbers to be configured PVID Port VLAN Identifier is a classification mechanism that associates a port with a ...

Page 48: ...ort filters drops the packet Disable disables Ingress filtering GVRP Disable Group VLAN Registration Protocol GVRP this enables the port to dynamically become a member of a VLAN Each port can be configured to use an Ingress Filter to enable or disable GVRP The ports to be configured in a given session can be identified by either entering a range of port numbers or by entering the PVID To configure...

Page 49: ...1 31 Edit 802 1Q VLANs Menu To edit an existing 802 1Q VLAN highlight the Action Add Modify field and toggle between Add Modify and Delete In the Add Modify mode both individual entrees to a selected VLAN and entire VLANs can be added In the Delete mode entire VLANs can be deleted VLANs to be edited can be selected by either the VID field or the VLAN Name fields Enter either the VID or the VLAN ...

Page 50: ... first field of Membership E F Each port s 802 1Q VLAN membership can be set individually by highlighting the port s entry using the arrow keys and then toggling between E F or using the space bar To edit a port s Tagged or Untagged status Highlight the first field of Tagging U T field Each port s state can be set by highlighting the port s entry using the arrow keys and then toggling between U or...

Page 51: ...r to setting up the corresponding IP interface An example is presented below VLAN Name VID Switch Ports System default 1 5 6 7 8 21 22 23 24 Engineering 2 9 10 11 12 Marketing 3 13 14 15 16 Finance 4 17 18 19 20 Sales 5 1 2 3 4 Backbone 6 25 26 Table 1 2 VLAN Example Assigned Ports In this case 6 IP interfaces are required so a CIDR notation of 10 32 0 0 11 or a 11 bit addressing scheme will work ...

Page 52: ...dress IP Address System default 1 10 32 0 0 10 32 0 1 Engineering 2 10 64 0 0 10 64 0 1 Marketing 3 10 96 0 0 10 96 0 1 Finance 4 10 128 0 0 10 128 0 1 Sales 5 10 160 0 0 10 160 0 1 Backbone 6 10 192 0 0 10 192 0 1 Table 1 3 VLAN Example Assigned IP Interfaces The 6 IP interfaces each with an IP address listed in the table above and a subnet mask of 255 224 0 0 can be entered into the Setup IP Int...

Page 53: ... VH 2402 L3 Management Guide 45 Figure 1 32 Layer 3 Main Menu Highlight Layer 3 IP Networking from the Main Menu and press enter Figure 1 33 Layer 3 IP Networking Menu Highlight Setup IP Interface and press enter ...

Page 54: ...he Active yes field to yes highlight APPLY and press enter to make the IP interface effective Use Save Changes from the Main Menu to enter the changes into NV RAM Parameter Description Action Add Modify This field can be toggled using the space bar between Add Modify and Delete Add Modify allows for the creation of a new IP interface or changes to an existing IP interface Delete allows for the del...

Page 55: ...and No using the space bar This entry determines whether the subnet will be active or not VID This field allows the entry of the VLAN ID number for the VLAN the IP interface belongs to Multicasting Layer 2 Multicast Setup To setup Multicasting on the switch when the switch is in Layer 2 operating mode highlight Multicasting from the Main Menu and press Enter Figure 1 35 Multicasting Menu ...

Page 56: ... State Non Querier field to the appropriate choice between Non Querier V1 Querier and V2 Querier to determine the version of IGMP that is used in your network A value between 2 and 255 can be entered for the Robustness Variable default is 2 The Query Interval 125 can be set between 1 and 65500 seconds default is 125 seconds This sets the time between IGMP queries The Max Response 10 allows a setti...

Page 57: ...hat are expected to lose a large number of packets A value between 2 and 255 can be entered with larger values being specified for sub networks that are expected to lose larger numbers of packets Query Interval 125 Allows the entry of a value between 1 and 65500 seconds with a default of 125 seconds This specifies the length of time between sending IGMP queries Max Response 10 Sets the maximum amo...

Page 58: ...ing to the VLAN that corresponds to the VID entered in the VID 2 field Each port of a given VLAN can be configured as an egress member a forbidden non member or as a non member of the multicast group that will receive multicast packets from the multicast MAC address by toggling the entry below each port of the VLAN to the appropriate code Parameter Description Action Add Modify The field can be to...

Page 59: ...s the port as being a static member of the multicast group Egress Member Ports are ports that will be transmitting traffic for the multicast group F Forbidden Non Member specifies the port as not being a member of the multicast group and that the port is forbidden from becoming a member of the multicast group dynamically Non Member specifies the port as not being a member of the multicast group bu...

Page 60: ... not send IGMP reports or implement IGMP snooping a multicast router connected to the router port of the Layer 3 switch would not be able to receive UDP data streams unless the UDP multicast packets were all forwarded to the router port A router port will be dynamically configured when IGMP query packets RIPv2 multicast DVMRP multicast PIM DM multicast packets are detected flowing into a port To s...

Page 61: ... router port by highlighting the port s entry using the arrow keys and then toggling between M and using the space bar M indicates a port is a member of the static group of router ports indicates a port is not a static member Layer 3 Multicasting When the switch is in IP Routing mode several functions supporting IP multicasting are added to the Multicasting menu These additional functions can be c...

Page 62: ...lticasting Settings from the Multicast Menu and press Enter Highlight Multicast Interface Configuration from the Setup Multicast Menu and press Enter Figure 1 40 Setup IP Multicast Menu Multicast Interface Configuration To configure the multicast interface highlight Multicast Interface Configuration and press Enter ...

Page 63: ...ast protocols are the Protocol Independent Multicast Dense Mode PIM DM and the Distance Vector Multicast Routing Protocol DVMRP INACT is not a multicast routing protocol It is used to make a given interface inactive for IP Multicast routing and can still route IP traffic Parameter Description Interface Name Allows the entry of the name of the IP interface that is to be configured for multicasting ...

Page 64: ...ve for IP Multicast routing yet can still route IP traffic IGMP Interface Configuration Figure 1 42 IGMP Interface Configuration This menu allows the configuration of IGMP for each IP interface configured on the switch IGMP can be configured as Version 1 or 2 by toggling the Ver 2 field The length of time between queries can be varied by entering a value between 1 and 65 500 seconds in the Query 1...

Page 65: ...e IGMP version 1 or 2 that will be used to interpret IGMP queries on the interface Robustness Variable 2 A tuning variable to allow for subnetworks that are expected to lose a large number of packets A value between 2 and 255 can be entered with larger values being specified for subnetworks that are expected to lose larger numbers of packets Query Interval 125 Allows the entry of a value between 1...

Page 66: ...ting entry Delete allows you to delete an existing entry Interface Name Enter the IP Interface name the IGMP Static Member belongs to in this field IGMP Static Group IP Enter the IP address of the IGMP Static Group in this field Group MAC Address Displays the MAC address corresponding to the IGMP Static Group IP address entered above IP Address Displays the IP address corresponding to the IP inter...

Page 67: ... Distance Vector Multicast Routing Protocol to be configured for each IP interface defined on the switch The Distance Vector Multicast Routing Protocol DVMRP is a hop based method of building multicast delivery trees from multicast sources to all nodes of a network Because the delivery trees are pruned and shortest path DVMRP is relatively efficient Because multicast group membership information i...

Page 68: ...s the message If the message is not received on the shortest path back to the source the message is dropped Route cost is a relative number that is used by DVMRP to calculate which branches of a multicast delivery tree should be pruned The cost is relative to other costs assigned to other DVMRP routes throughout the network The higher the route cost the lower the probability that the current route...

Page 69: ...o the IP Interface name entered above Probe Interval 10 The Probe Interval 10 field allows an entry between 0 and 65 535 seconds and defines the interval between probes DVMRP defines an extension to IGMP that allows routers to query other routers to determine if a multicast group is present on an given IP interface or not The default is 10 Include Unknown Neighbor Report Disabled Allows the L3 swi...

Page 70: ...cast group members PIM DM has no explicit join messages It relies upon periodic flooding of multicast messages to all interfaces and then either waiting for a timer to expire the Join Prune Interval or for the downstream routers to transmit explicit prune messages indicating that there are no multicast members on their respective branches PIM DM then removes these branches prunes them from the mul...

Page 71: ...ill begin transmitting Hello messages to advertise its availability to become the root router The default is 30 seconds Join Prune Interval 60 This field allows an entry of between 0 and 9 999 seconds and determines the interval between transmitting flooding to all interfaces multicast messages to downstream routers and automatically pruning a branch from the multicast delivery tree This interval ...

Page 72: ...9033691 01 is Disabled Port Mirroring To configure a port for port mirroring Highlight Mirroring from the Main Menu and press enter Figure 1 46 Mirroring Menu To select the target port highlight Target Port Selection and press enter ...

Page 73: ... Mirroring Settings and press enter Figure 1 48 Port Mirroring Settings Up to 25 entries can be made to the port mirroring table but it should be noted that a faster port a 1000 Mbps Gigabit Ethernet port for example should not be mirrored to a slower port one of the 24 100 Mbps Fast Ethernet port because many packets will be dropped Parameter Description Action Add Modify This field can be toggle...

Page 74: ...ther Ingress and Egress Ingress mirrors only received packets while Egress mirrors only transmitted packets Priority To configure a forwarding priority for a given MAC address highlight Priority from the main menu and press Enter Figure 1 49 Setup MAC Address Priority Parameter Description Action Add Modify This field can be toggled between Add Modify and Delete using the space bar VID 1 Allows th...

Page 75: ...ing to the priority of packets sent to or transmitted from the MAC address entered above Source Destination Src This field can be toggled using the space bar between Src Source Dst Destination and Either corresponding to whether the MAC address entered above will be transmitting packets a source receiving packets a destination or both either Filtering Layer 2 Filtering To enter a MAC address into ...

Page 76: ...e switch can also be configured to filter all packets to or from this MAC address either a source or a destination Parameter Description Action Add Modify This field can be toggled between Add Modify and Delete using the space bar VID Allows the entry of the VLAN ID VID of the VLAN to which the MAC address below is a member of MAC Address Allows the entry of a MAC address to be filtered from the s...

Page 77: ... a source receiving packets a destination or both either Layer 3 IP Routing Filtering With the switch configured to Layer 3 Operation mode both MAC and IP addresses can be entered into the filtering table using there respective entry menus To enter an address highlight Filtering from the Main Menu and press enter Figure 1 52 Filtering Menu Layer 3 ...

Page 78: ...eld can be toggled between Src source Dst destination and Either The IP address entered into the filtering table can be filtered as a source packets will not be received from the IP address as a destination packets will not be transmitted to the IP address or as either a source or destination packets will not be received from or transmitted to the IP address Forwarding Layer 2 Forwarding To enter ...

Page 79: ...orwarding from the Forwarding Menu and press enter Figure 1 55 Static Unicast MAC Forwarding Setup Parameter Description Action Add Modify The field can be toggled between Add Modify and Delete using the space bar VID Allows the entry of the VLAN ID VID of the VLAN the MAC address below is a member of ...

Page 80: ...rwarding Static Default Routes With the switch in Layer 3 Operation mode entries into the switch s forwarding table can be made using both MAC addresses and IP addresses Static IP forwarding is accomplished by the entry of an IP address into the Static IP Routing table Static Address Resolution Protocol ARP entrees can also be made from the Forwarding Menu Highlight Static Default Routes from the ...

Page 81: ...able Subnet Mask Allows the entry of a subnet mask corresponding to the IP address above Gateway IP Allows the entry of an IP address of a default gateway for the IP address above Metric 1 Allows the entry of a routing protocol metric representing the number of routers between the switch and the IP address above Static ARP To make a static ARP entry highlight Static ARP from the Forwarding menu an...

Page 82: ...ess of the ARP entry MAC Address The MAC address of the ARP entry Spanning Tree Switch Spanning Tree Settings To globally configure STP on the switch highlight Spanning Tree on the main menu and press Enter Figure 1 58 Configure Spanning Tree Global The Spanning Tree Protocol STP operates on two levels on the switch level the settings are globally implemented On the port level the settings are imp...

Page 83: ...rom 6 to 40 seconds At the end of the Max Age if a BPDU has still not been received from the Root Bridge your Switch will start sending its own BPDU to all other Switches for permission to become the Root Bridge If it turns out that your Switch has the lowest Bridge Identifier it will become the Root Bridge Hello Time The Hello Time can be set from 1 to 10 seconds This is the interval between two ...

Page 84: ...e Max Age Otherwise a configuration error will occur Observe the following formulas when setting the above parameters Max Age 2 x Forward Delay 1 second Max Age 2 x Hello Time 1 second STP Group Confugration To define which ports will be members of an STP Group highlight Group Create Delete and press enter Figure 1 59 STP Group Configuration Toggle the Action Add Modify field to Add Modify Choose ...

Page 85: ...9033691 01 VH 2402 L3 Management Guide 77 have to correspond to any name that has been previously entered in the switch s configuration ...

Page 86: ...e of its own configuration settings An STP Group will use the switch level parameters entered above with the addition of Port Priority and Port Cost An STP Group spanning tree works in the same way as the switch level spanning tree but the root bridge concept is replaced with a root port concept A root port is a port of the group that is elected on the basis of port priority and port cost to be th...

Page 87: ...ole Configure Ports to Allows the entry of a range of port numbers to be configured Port Cost A Port Cost can be set from 1 to 65535 The lower the number the greater the probability the port will be chosen to forward packets Priority A Port Priority can be from 0 to 255 The lower the number the greater the probability the port will be chosen as the Root Port Port Trunking To configure a port trunk...

Page 88: ... trunked ports must all be of the same speed and should be configured as full duplex The configuration of the lowest numbered port in the group becomes the configuration for all of the ports in the aggregation group This port is called the Master Port of the group and all configuration options including the VLAN configuration that can be applied to the Master Port are applied to the entire port tr...

Page 89: ... the entry of the number of contiguous ports that will make up the port trunking group These ports will be in sequential order from the Master Port Method Disabled This field can be toggled between Enabled and Disabled This is used to turn a port trunking group on or off This is useful for diagnostics to quickly isolate a bandwidth intensive network device or to have an absolute backup aggregation...

Page 90: ...rotocol TFTP services allow the switch firmware to be upgraded by transferring a new firmware file from a TFTP server to the switch A configuration file can also be loaded into the switch from a TFTP server switch settings can be saved to the TFTP server and a history log can be uploaded from the switch to the TFTP server Updating Firmware To update the switch s firmware highlight Upgrade Firmware...

Page 91: ...he TFTP server must be running TFTP server software to perform the file transfer TFTP server software is a part of many network management software packages such as NetSight or can be obtained as a separate program Highlight APPLY and press enter to record the IP address of the TFTP server Use Save Changes from the Main Menu to enter the address into NV RAM Highlight START and press enter to initi...

Page 92: ...ation file on the TFTP server Highlight APPLY and press enter record the IP address of the TFTP server Use Save Changes from the Main Menu to enter the address into NV RAM Highlight START and press enter to initiate the file transfer Uploading a Settings File To upload a settings file to the TFTP server highlight Upload configuration file to TFTP Server and press enter ...

Page 93: ... TFTP server and the path and filename of the settings file on the TFTP server and press APPLY Highlight START and press enter to initiate the file transfer Uploading a History Log File To save a History Log on a TFTP server highlight Save Log to TFTP Server and press enter Figure 1 66 Upload Log File ...

Page 94: ...n with another network device using Ping highlight Ping Test and press enter Figure 1 67 Ping Connectivity Test Enter the IP address of the network device to be pinged and the number of test packets to be sent 3 is usually enough Highlight START and press enter to initiate the ping program Layer 3 Utilities Layer 3 IP Routing switch operation mode adds BOOTP Relay and DNS Relay to the utilities av...

Page 95: ...Relay service on the switch The default is Disabled BOOTP HOPS Count Limit 4 This field allows an entry between 1 and 16 to define the maximum number of router hops BOOTP messages can be forwarded across The default hop count is 4 BOOTP DHCP Relay Time Threshold 4 Allows an entry between 0 and 65535 seconds and defines the maximum time limit for routing a BOOTP DHCP packet If a value of 0 is enter...

Page 96: ...n be toggled between Add and Delete using the space bar Toggle to Add and enter the subnet name for which BOOTP Relay will be active Interface Name The interface name of the IP interface on which the BOOTP or DHCP servers reside on IP Address Displays the IP address corresponding to the subnet name entered above BOOTP DHCP Server Allows the entry of IP addresses for up to four BOOTP or DHCP server...

Page 97: ...field can be toggled between Disabled and Enabled using the space bar and is used to enable or disable the DNS Relay service on the switch Name Server 1 Allows the entry of the IP address of a primary number 1 and a secondary number 2 domain name server DNS DNSR Cache Status Disabled This can be toggled between Disabled and Enabled This determines if a DNS cache will be enabled on the switch DNSR ...

Page 98: ...e DNS Relay menu and press Enter Figure 1 71 DNS Relay Setup Parameter Description Action Add Edit The Action Add Edit field can be toggled between Add Edit and Delete Enter the Domain name and its corresponding IP address Domain Name The domain name of the static DNS table entry IP Address The IP address of the domain name above Status Enabled This field can be toggled using the space bar between...

Page 99: ... monitoring functions are visible on the console when the switch is in Layer 2 Only operating mode Layer 3 network monitoring functions are added to the console when the switch is in IP Routing operating mode Layer 2 Network Monitoring Layer 2 network monitoring consists of the following screens or menus Port Utilization Port Error Packets Port Packet Analysis Browse MAC Address Table view the MAC...

Page 100: ... Figure 1 72 Network Monitoring Menu Port Utilization The Port Utilization screen shows the number of packets transmitted and received per second and calculates the percentage of the total available bandwidth being used on the port displayed under Util To view the port utilization Highlight Port Utilization on the Network Monitoring menu and press enter ...

Page 101: ... The default is 2 seconds TX sec The rate at which the given port is transmitting packets in packets per second RX sec The rate at which the given port is receiving packets in packets per second Util The percentage utilization of the given port s available bandwidth Port Error Statistics The Port Error Statistics screen displays the packet errors that the switch can detect and displays the results...

Page 102: ... will be displayed Enter the port number of the port to be viewed The Interval 2 sec field can be toggled from 2 seconds to 1 minute or suspend This sets the interval at which the error statistics are updated Parameter Description Interval 2 sec The interval in seconds that the table is updated The default is 2 seconds RX Frames Received packets CRC Error For 10 Mbps ports the counter records CRC ...

Page 103: ...ctets and had either an FCS or an alignment error Jabber The total number of frames received that were longer than 1518 octets excluding framing bits but including FCS octets and had either an FCS or an alignment error Drop Pkts The total number of events in which packets were dropped due to a lack of resources TX Frames Transmitted packets ExDefer The number of frames for which the first transmis...

Page 104: ...ited by more than one collision Coll An estimate of the total number of collisions on this network segment Port Packet Analysis Table The Port Packet Analysis Table displays the size of packets received or transmitted by a given switch port In addition statistics on the number and rate of unicast multicast and broadcast packets received by the switch are displayed To view an analysis of packets re...

Page 105: ...s given by the column on the right Frames sec The number of packets or frames transmitted or received per second by the switch Unicast RX Displays the number of unicast packets received by the switch in total number Frames and the rate Frames sec Multicast RX Displays the number of multicast packets received by the switch in total number Frames and the rate Frames sec Broadcast RX Displays the num...

Page 106: ...otal and rate Total sec TX Frames Displays the number of packets frames transmitted by the switch in total number Total and rate Total sec MAC Address Forwarding Table This allows the switch s dynamic MAC address forwarding table to be viewed When the switch learns an association between a MAC address and a port number it makes an entry into its forwarding table These entries are then used to forw...

Page 107: ...search for a particular MAC address Toggle the Browse By ALL field to MAC Address A MAC Address 000000000000 field will appear Enter the MAC address in the field and press enter GVRP Status Table This allows the GVRP status for each of the switch s ports to be viewed by VLAN The GVRP status screen displays the ports on the switch that are currently Egress or Untagged ports To view the GVRP status ...

Page 108: ...nfigured as router ports A router port configured by a user using the console or web based management interfaces is displayed as a static router port designated by S A router port that is dynamically configured by the switch is designated by D To view the Router Port table Highlight Browse Router Port from the Network Monitoring menu and press Enter ...

Page 109: ...d router port configured by the switch IGMP Snooping Table This allows the switch s IGMP Snooping table to be viewed IGMP Snooping allows the switch to read the Multicast Group IP address and the corresponding MAC address from IGMP packets that pass through the switch The ports where the IGMP packets were snooped are displayed signified with an M The number of IGMP reports that were snooped are al...

Page 110: ...the Switch History Log to be viewed The switch records all traps in sequence that identify events on the switch The time since the last cold start of the switch is also recorded To view the switch history log Highlight Switch History from the Network Monitoring menu and press enter Figure 1 80 Switch History Table ...

Page 111: ...g menu The following items are added to the Network Monitoring menu when the switch is in Layer 3 IP Routing mode Browse IP Address Routing Table ARP Table IP Multicast Forwarding Table IGMP Group Table DVMRP Routing Table To view the Network Monitoring menu Highlight Network Monitoring from the Main Menu and press Enter Figure 1 81 Network Monitoring Menu Layer 3 ...

Page 112: ...rom the Network Monitoring menu and press enter Figure 1 82 IP Forwarding Table Layer 3 To display a particular IP address enter the IP address in the Jump to IP Address 0 0 0 0 field highlight GO and press enter Routing Table To view the contents of the IP Routing table Highlight Routing Table on the Network Monitoring menu and press Enter ...

Page 113: ...tion IP address enter either the IP address in the Jump to Destination Address 0 0 0 0 field the gateway address in the Gateway 0 0 0 0 field or the subnet mask in the Mask 0 0 0 0 field highlight GO and press enter ARP Table To view the ARP table Highlight ARP Table on the Network Monitoring menu and press enter ...

Page 114: ... interface name in the Jump to Interface Name field or enter the IP address in the IP Address 0 0 0 0 field highlight GO and press enter IP Multicast Forwarding Table To view the IP multicast forwarding table Highlight IP Multicast Forwarding Table from the Network Monitoring menu and press enter Figure 1 85 View the IP Multicast Forwarding Table ...

Page 115: ...e table are displayed To display a particular source IP address enter either the IP address in the Jump to IP Address 0 0 0 0 field or the source subnet mask in the Source Mask 0 0 0 0 field highlight GO and press enter IGMP Group Table To view the IGMP Group table Highlight IGMP Group Table from the Network Monitoring menu and press Enter Figure 1 86 Browse IGMP Group Table To display a particula...

Page 116: ...e DVMRP Routing Table The Jump to Source IP Address and Source Mask fields allow the entry of an IP address and corresponding subnet mask to search the table for Highlight GO and press enter and the DVMRP Routing table will be searched for the IP address and subnet mask above Load Factory Defaults To reset the switch to all factory defaults Highlight Reboot on the main menu and press enter ...

Page 117: ...gure 1 88 Reboot Highlight one of the two Load Factory Default Configuration entries and press enter A confirmation screen will appear Press Y for Yes and press enter The factory defaults for the VH 2402 L3 are listed in Appendix D of this manual ...

Page 118: ...figuration settings not saved using Save Changes from the Main Menu will be lost The switch s configuration will be restored to the last configuration saved in NV RAM Save Configuration Reboot saves the configuration to NV RAM identical to using Save Changes and then restarts the switch Reboot Load Factory Default Configuration restarts the switch using the default factory configuration All config...

Page 119: ...estarts the switch using the default factory configuration except the user configured IP address will be retained All other configuration data will be lost A confirmation screen will appear Figure 1 90 System Reboot Confirmation To reboot the switch in the mode entered above highlight Yes and press enter ...

Page 120: ...rotocol Collecting information about the status and current configuration of network devices Modifying the configuration of network devices The VH 2402 L3 has a software program called an agent that processes SNMP requests but the user program that makes the requests and collects the responses runs on a management station a designated computer on the network The SNMP agent and the user program bot...

Page 121: ...twork You can also specify which network managers may receive traps from the Switch by entering a list of the IP addresses of authorized network managers Up to four trap recipient IP addresses and four corresponding SNMP community strings can be entered SNMP community strings function like passwords in that the community string entered for a given IP address must be used in the management station ...

Page 122: ...able when more than thirty two collisions occur while transmitting at 10Mbps or more than sixty four collisions occur while transmitting at 100Mbps Broadcast Multicast Storm This trap is sent whenever the port reaches the threshold in packets per second set globally for the switch Counters are maintained for each port and separate counters are maintained for broadcast and multicast packets The swi...

Page 123: ...by request If your software provides functions to browse or modify MIBs you can also get the MIB values and change them if the MIBs attributes permit the write operation This process however can be quite involved since you must know the MIB OIDs and retrieve them one by one Packet Forwarding The Switch enters the relationship between destination MAC or IP addresses and the Ethernet port or gateway...

Page 124: ...benefits of having a switch Static forwarding entries are not affected by the aging time Filtering The switch uses a filtering database to segment the network and control communication between segments It can also filter packets off the network for intrusion control Static filtering entries can be made by MAC Address or IP Address filtering Each port on the switch is a unique collision domain and ...

Page 125: ...ntry of specific IP addresses to be filtered from the network switch must be in IP Routing mode Packets sent from one manually entered IP address to another can be filtered from the network The entry may specified as either a source a destination or both switch must be in IP Routing mode Spanning Tree The IEEE 802 1D Spanning Tree Protocol allows for the blocking of links between switches that for...

Page 126: ... Root Port and the Designated Ports The following are the user configurable STP parameters for the switch level Parameter Description Default Value Bridge Identifier Not user configurable except by setting priority below A combination of the User set priority and the switch s MAC address The Bridge Identifier consists of two parts a 16 bit priority and a 48 bit Ethernet MAC address 32768 MAC Prior...

Page 127: ...ve priority for each port lower numbers give a higher priority and a greater chance of a given port being elected as the root port 128 Port Cost A value used by STP to evaluate paths STP calculates path costs and selects the path with the minimum cost as the active path 19 100Mbps Fast Ethernet ports 10 1000Mbps Gigabit Ethernet ports Table 2 2 STP Parameters Port Group Level Bridge Protocol Data ...

Page 128: ...rame to calculate a BPDU and if the topology changes initiates a BPDU transmission The communication between switches via BPDUs results in the following One switch is elected as the root switch The shortest distance to the root switch is calculated for each switch A designated switch is selected This is the switch closest to the root switch through which packets will be forwarded to the root A por...

Page 129: ... starting to forward packets They must also wait for the packet lifetime to expire for BPDU packets that were forwarded based on the old topology The forward delay timer is used to allow the network topology to stabilize after a topology change In addition STP specifies a series of states a port must transition through to further ensure that a stable network topology is created after a topology ch...

Page 130: ...cking From blocking to listening or to disabled From listening to learning or to disabled From learning to forwarding or to disabled From forwarding to disabled From disabled to blocking Figure 2 1 STP Port State Transitions When STP is enabled every port on every switch in the network goes through the blocking state and then transitions ...

Page 131: ...le STA Parameters The factory default setting should cover the majority of installations However it is advisable to keep the default settings as set at the factory unless it is absolutely necessary The user changeable parameters in the Switch are as follows Priority A Priority for the switch can be set from 0 to 65535 0 is equal to the highest Priority Hello Time The Hello Time can be from 1 to 10...

Page 132: ... Forward Delay 1 second Max Age 2 x Hello Time 1 second Port Priority A Port Priority can be from 0 to 255 The lower the number the greater the probability the port will be chosen as the Root Port Port Cost A Port Cost can be set from 1 to 65535 The lower the number the greater the probability the port will be chosen to forward packets Illustration of STP A simple illustration of three Bridges or ...

Page 133: ...the defaults can be complex Therefore you are advised to keep the default factory settings and STP will automatically assign root bridges ports and block loop connections Influencing STP to choose a particular switch as the root bridge using the Priority setting or influencing STP to choose a particular port to block using the Port Priority and Port Cost settings is however relatively straight for...

Page 134: ...Gigabit ports could be used but the port cost should be increased from the default to ensure that the link between switch B and switch C is the blocked link Port Trunking Port trunking is used to combine a number of ports together to make a single high bandwidth data pipeline The participating parts are called members of a port trunking group with one port designated as the master port of the grou...

Page 135: ...ists of the 2 optional Gigabit Ethernet ports of the front panel These ports are the two 1000BASE SX LX TX or GBIC ports contained in a front panel mounted module Figure 2 4 Port trunking Group Data transmitted to a specific host destination address will always be transmitted over the same port in a trunk group This allows packets in a data stream to arrive in the same Port Trunking Group ...

Page 136: ...broadcast packets are forwarded only to members of the VLAN on which the broadcast was initiated Notes About VLANs on the VH 2402 L3 1 The VH 2402 L3 supports IEEE 802 1Q VLANs The port untagging function can be used to remove the 802 1Q tag from packet headers to maintain compatibility with devices that are tag unaware that is network devices that do not support IEEE 802 1Q VLANs or tagging 2 The...

Page 137: ...1Q VLANs require tagging which enables the VLANs to span an entire network assuming all switches on the network are IEEE 802 1Q compliant Any port can be configured as either tagging or untagging The untagging feature of IEEE 802 1Q VLANs allow VLANs to work with legacy switches that don t recognize VLAN tags in packet headers The tagging feature allows VLANs to span multiple 802 1Q compliant swit...

Page 138: ...e is indicated by a value of 0x8100 in the EtherType field When a packet s EtherType field is equal to 0x8100 the packet carries the IEEE 802 1Q 802 1p tag The tag is contained in the following two octets and consists of 3 bits or user priority 1 bit of Canonical Format Identifier CFI used for encapsulating Token Ring packets so they can be carried across Ethernet backbones and 12 bits of VLAN ID ...

Page 139: ...e entire packet longer by 4 octets All of the information contained in the packet originally is retained Figure 2 6 IEEE 802 1Q Tag The EtherType and VLAN ID are inserted after the MAC source address but before the originial EtherType Length or Logical Link Control Because the packet is now a bit longer than it was originally the Cyclic Redundancy Check CRC must be recalculated ...

Page 140: ...Prior to the adoption 802 1Q VLANs port based and MAC based VLANs were in common use These VLANs relied upon a Port VLAN ID PVID to forward packets A packet received on a given port would be assigned that port s PVID and then be forwarded to the port that corresponded to the packet s destination address found in the switch s forwarding table If the PVID of the port that received the packet is diff...

Page 141: ...e packet Because of the existence of the PVID for untagged packets and the VID for tagged packets tag aware and tag unaware network devices can coexist on the same network A switch port can have only one PVID but can have as many VIDs as the switch has memory in its VLAN table to store them Because some devices on a network may be tag unaware a decision must be made at each port on a tag aware dev...

Page 142: ...rward the packet If the packet is tagged with VLAN information the ingress port will first determine if the ingress port itself is a member of the tagged VLAN If it is not the packet will be dropped If the ingress port is a member of the 802 1Q VLAN the switch then determines if the destination port is a member of the 802 1Q VLAN If it is not the packet is dropped If the destination port is a memb...

Page 143: ...kets will be forwarded to any destination port Packets with unknown source addresses will be flooded to all ports Broadcast and multicast packets will also be flooded to all ports A VLAN that does not have a corresponding IP interface defined for it will function as a Layer 2 Only VLAN regardless of the Switch Operation mode Layer 3 Based VLANs Layer 3 based VLANs use network layer addresses subne...

Page 144: ...of a network sharing a particular network address Subnet mask a 32 bit number used to describe which portion of a Network Address refers to the subnet and which portion refers to the host Subnet masks have the form xxx xxx xxx xxx Interface a network connection IP Interface another name for subnet Network Address the resulting 32 bit number from a bitwise logical AND operation performed between an...

Page 145: ... a long string of binary digits 32 binary digits or 32 bits IP addresses are 32 bit addresses The three IP addresses in the example above written in binary form are 1 11010010 11001010 11001100 11001101 2 10111101 00010101 11110001 00111000 3 01111101 01010111 00000000 00000001 The dots are included to make the numbers easier to read Eight binary bits are called a byte or an octet An octet can rep...

Page 146: ... second number called the Subnet mask is the other part To make this a bit more confusing the subnet mask has the same numerical form as an IP address Address Classes Address classes refer to the range of numbers in the subnet mask Grouping the subnet masks into classes makes the task of dividing a network into subnets a bit easier There are 5 address classes The first 4 bits in the IP address det...

Page 147: ...ss so the Network part of the address called the Network Address is the first octet 10 x x x The node part of the address is the last three octets x 42 73 210 To specify the network address for a given IP address the node part is set to all 0 s In our example 10 0 0 0 specifies the network address for 10 42 73 210 When the node part is set to all 1 s the address specifies a broadcast address So 10...

Page 148: ...ult defines the Subnet Address Some restrictions apply to subnet addresses Addresses of all 0 s and all 1 s are reserved for the local network when a host does not know it s network address and for all hosts on the network the broadcast address This also applies to subnets A subnet address cannot be all 0 s or all 1 s A 1 bit subnet mask is also not allowed Calculating the Number of Subnets and No...

Page 149: ...f the address is 24 3 21 bits so the total number of nodes is 221 2 2 097 152 2 2 097 150 Multiplying the number of subnets times the number of nodes gives 12 582 900 possible nodes Note that this is less than the 16 777 214 possible nodes that an unsubnetted class A network would have Subnetting reduces the number of possible nodes for a given network but increases the segmentation of the network...

Page 150: ... 0 21 8190 2046 16756740 14 255 255 252 0 22 16382 1022 16742404 15 255 255 254 0 23 32766 510 16710660 16 255 255 255 0 24 65534 254 16645636 17 255 255 255 128 25 131070 126 16514820 18 255 255 255 192 26 262142 62 16252804 19 255 255 255 224 27 525286 30 15728580 20 255 255 255 240 28 1048574 14 14680036 21 255 255 255 248 29 2097150 6 12582900 22 255 255 255 252 30 4194302 2 8388604 Table 2 5 ...

Page 151: ... Interfaces The Layer 3 switch allows ranges of IP addresses OSI layer 3 to be assigned to VLANs OSI layer 2 Each VLAN must be configured prior to setting up the corresponding IP interface An IP addressing scheme must then be established and implemented when the IP interfaces are set up on the switch An example is presented below VLAN Name VID Switch Ports System default 1 5 6 7 8 21 22 23 24 Engi...

Page 152: ...range of IP addresses for each subnet can be chosen as an IP address for an IP interface on the switch For this example we have chosen the next IP address above the network address VLAN Name VID Network Address IP Address System default 1 10 32 0 0 10 32 0 1 Engineering 2 10 64 0 0 10 64 0 1 Marketing 3 10 96 0 0 10 96 0 1 Finance 4 10 128 0 0 10 128 0 1 Sales 5 10 160 0 0 10 160 0 1 Backbone 6 10...

Page 153: ...any routing function between these VLANs is referred to as performing IP Switching Internet Protocols This is a brief introduction to the suite of Internet Protocols frequently referred to as TCP IP It is intended to give the reader a reasonable understanding of the available facilities and some familiarity with terminology It is not intended to be a complete description Protocol Layering The Inte...

Page 154: ...ate and interoperate This requires very well defined and well known methods for transferring messages and data This is accomplished through the protocol stack Protocol layering as simply a tool for visualizing the organization of the necessary software and hardware in a network In this view Layer 2 represents switching and Layer 3 represents routing Protocol layering is actually a set of guideline...

Page 155: ...acks from the same software vendor may communicate in the same way Two stacks from different software vendors or different products from the same vendor may communicate in completely different ways As long as peers can communicate and interoperate this has no impact on the functioning of the network The communication between layers within a given protocol stack can be both different from a second ...

Page 156: ...ternet usually requires a router and a modem or other device to connect to an Internet Service Provider s WAN These are Layer 3 functions Layer 3 Commonly referred to as the routing layer this layer provides logical partitioning of networks subnetting scalability security and Quality of Service QoS The backbone of the Internet is built using Layer 3 functions IP is the premier Layer 3 protocol IP ...

Page 157: ...tolerate the overhead and latency of TCP TCP and UDP also differ in the amount of error recovery provided and whether or not it is visible to the user application Both TCP and UDP are layered on IP which has minimal error recovery and detection TCP forces retransmission of data that was lost by the lower layers UDP does not Layer 7 This layer known as the application layer provides access to eithe...

Page 158: ...received and retransmits any packets that are lost or dropped TCP also handles the division of large messages into several Ethernet packets and makes sure these packets are received and reassembled in the correct order Because these functions are required by a large number of applications they are grouped into a single protocol rather than being the part of the specifications for just sending e ma...

Page 159: ...This process is referred to as encapsulation Many levels of encapsulation are required for a packet to cross the Internet Packet Headers TCP Most data transmissions are much longer that a single packet The data must then be divided up among a series of packets These packets must be transmitted received and then reassembled into the original data TCP handles these functions TCP must know how large ...

Page 160: ...When packets have been successfully received TCP sends an acknowledgement This is simply a packet that has the acknowledgement number field filled in An acknowledgement number of 1000 indicates that all of the data up to octet 1000 has been received If the transmitting TCP does not receive an acknowledgement in a reasonable amount of time the data is resent The window field controls the amount of ...

Page 161: ...tion IP addresses IP is only concerned with these IP addresses It is not concerned with the contents of the packet or the TCP header IP finds a route for the packet to get to the other end of the TCP connection IP adds its own header to the packet to accomplish this The IP header contains the source and destination addresses the protocol number and another checksum The protocol number tells the re...

Page 162: ...Every active Ethernet device has its own Ethernet address commonly called the MAC address assigned to it by the manufacturer Ethernet uses 48 bit addresses The Ethernet header is 14 octets that include the source and destination MAC address and a type code There is no relationship between the MAC address of a network node and its IP address There must be a database of Ethernet addresses and their ...

Page 163: ...data from the headers to reassemble the data into the original file TCP and UDP Well Known Ports Application protocols run on top of TCP IP When an application wants to send data or a message it gives the data to TCP Because TCP and IP take care of the networking details the application can look at the network connection as a simple data stream To transfer a file across a network using the File Tr...

Page 164: ...ber in order to send commands The FTP Server can use any TCP port number to send the file so long as it is sent as part of the connection setup A TCP connection is then described by a set of four numbers the IP address and TCP port number for the local computer and the IP address and TCP port number for the remote computer The IP address is in the IP header and the TCP port number is in the TCP he...

Page 165: ... The user s computer must be able to determine the remote computer s address before a connection can be made A designated computer on the network will contain a database of computer names and their corresponding IP and MAC addresses The user s computer will send a query to the name database computer and the database computer will send a response Both the query and the response are very short There...

Page 166: ...use its messages are processed by the network software The Domain Name System Computer users usually prefer to use text names for computers they may want to open a connection with Computers themselves require 32 bit IP addresses Somewhere a database of network devices text names and their corresponding IP addresses must be maintained The Domain Name System DNS is used to map names to IP addresses ...

Page 167: ...me translation or simply return the address of the next DNS server if the server receiving the query cannot resolve the name When a DNS server receives a query it checks to see if the name is in its subdomain If it is the server translates the name and appends the answer to the query and sends it back to the client If the DNS server cannot translate the name it determines what type of name resolut...

Page 168: ...he same IP address to a given network device or computer each time If the IP address lease expires the network device sends a message to the DHCP server requesting a lease renewal The DHCP server can send an acknowledgement containing a new lease and updated configuration information If an IP address lease cannot be renewed the network device or computer sends a request to all local DHCP servers a...

Page 169: ... network interfaces or a specialized device with multiple network interfaces The device is designed to forward packets from one network to another IP routing is based on the network address of the destination IP address Each computer has a table of network addresses For each network address a corresponding gateway is listed This is the gateway to use to communicate with that network The gateway do...

Page 170: ...icient than small ones It is preferable to use the largest possible packet size but still be able to cross networks that require smaller packets To do this IP can negotiate packet size between the local and remote ends of a connection When an IP connection is first made the IPs at both ends of the connection state the largest packet they can handle The smaller of the two is selected When a IP conn...

Page 171: ...ot have an ARP cache entry the local computer must send an ARP request and wait for a reply When the local computer receives the ARP reply packet the local ARP reads the IP MAC address pair and then checks the ARP cache for this entry If there is an entry it is updated with the new information If there is no entry a new entry is made There are two possible cases when an ARP packet is received by a...

Page 172: ...Authority IANA for special purposes For example the block of multicast addresses ranging from 224 0 0 1 to 224 0 0 225 is reserved for use by routing protocols and some other low level topology discovery and maintenance protocols Figure 2 14 Class D Multicast Address Some of the reserved IP multicast addresses are as follows Address Assignment 224 0 0 0 Base Address reserved 224 0 0 1 All Systems ...

Page 173: ...ssigned 224 0 0 21 DVMRP on MOSPF Table 2 10 Reserved Multicast Address Assignment Internet Group Management Protocol IGMP End users that want to receive multicast packets must be able to inform nearby routers that they want to become a multicast group member of the group these packets are being sent to The Internet Group Management Protocol IGMP is used by multicast routers to maintain multicast ...

Page 174: ...lticast packets from this source If there is one member the packet is forwarded If there are no members the packet is dropped IGMP Versions 1 and 2 Users that want to receive multicast packets need to be able to join and leave multicast groups This is accomplished using IGMP Figure 2 15 IGMP Message Format The IGMP Type codes are shown below Type Meaning 0x11 Membership Query if Group Address is 0...

Page 175: ...ks If there is no response from a particular group the router assumes that there are no group members on the network and multicast packets are not forwarded The TTL field of query messages is set to 1 so that the queries do not get forwarded to other subnetworks IGMP version 2 introduces a few extensions to IGMP version 1 such as the election of a single multicast querier for each network explicit...

Page 176: ...icast trees where the multicast router is the trunk the branches are the various subnetworks that may be present and the leaves are end recipients of the multicast packets Several algorithms have been developed to construct these trees and to prune branches that have no active mulitcast group members Flooding The simplest algorithm for the delivery of multicast packets is for the multicast router ...

Page 177: ...very tree that spans the entire network with a single active link between routers or subnetwork is called a multicast spanning tree Links or branches are chosen such that there is only one active path between any two routers When a router receives a multicast packet it forwards the packet on all links except the one on which it was received This guarantees that all routers in the network will rece...

Page 178: ...r subnetwork Since multicast packets are forwarded through the shortest route between source and destination RPB is fast A given router also does not need information about the entire spanning tree nor does it need a mechanism to stop the forwarding of packets RPB does not use multicast group membership information in its forwarding decisions Reverse Path Multicasting RPM Reverse Path Multicasting...

Page 179: ...ed from it s memory and the entire process repeats This gives all subsequent routers on the network a chance to receive multicast packets from all multicast sources on the network It also gives all user s a chance to join a given multicast group Multicast Routing Protocols This section contains an overview of two multicast routing protocols Distance Vector Multicast Routing Protocol DVMRP and Prot...

Page 180: ...ck at a time toward a multicast source until they reach a router that is on an active branch of the multicast delivery tree If there is more than one multicast router on a network the one that has the shortest path back to the multicast source is elected to forward multicast packets from that source All other routers will discard multicast packets from that source If two multicast routers on a net...

Page 181: ... routes to others through RIP messages while passive devices listen to these messages Both active and passive routers update their routing tables based upon RIP messages that active routers exchange Only routers can run RIP in the active mode Every 30 seconds a router running RIP broadcasts a routing update containing a set of pairs of network addresses and a distance represented by the number of ...

Page 182: ...ve a low maximum value Infinity that is the network is unreachable is defined as 16 hops In other words if a network is more than 16 routers from the source the local router will consider the network unreachable RIP can also be slow to converge to remove inconsistent unreachable or looped routes from the routing table because RIP messages propagate relatively slowly through a network Slow converge...

Page 183: ...02 L3 Management Guide 175 RIP Version 1 Message Format There are two types of RIP messages routing information messages and information requests The same format is used by both types Figure 2 17 RIP v 1 Message Format ...

Page 184: ... The field VERSION contains the protocol version number 1 in this case and is used by the receiver to verify which version of RIP the packet was sent from RIP 1 Message RIP is not limited to TCP IP Its address format can support up to 14 octets when using IP the remaining 10 octets must be zeros Other network protocol suites can be specified in the Family of Source Network field IP has a value of ...

Page 185: ...st send different update messages for each IP interface to which it is connected Interfaces that use the same subnet mask as the router s network can contain subnetted routes other interfaces cannot The router will then advertise only a single route to the network RIP Version 2 Extensions RIP version 2 includes an explicit subnet mask entry so RIP version 2 can be used to propagate variable length...

Page 186: ...lso adds a 16 bit route tag that is retained and sent with router updates It can be used to identify the origin of the route Because the version number in RIP2 occupies the same octet as in RIP1 both versions of the protocols can be used on a given router simultaneously without interference ...

Page 187: ... Loop In this example B has been elected as the designated bridge and port 2 on C is in the blocking state The election of B as the designated bridge is determined by the exchange of BPDUs between B and C B had a better BPDU than C B continues sending BPDUs advertising its superiority over the other bridges on this LAN Should C fail to receive these BPDUs for longer than the MAX AGE default of 20 ...

Page 188: ...plex state of two ports is a very common configuration error for a point to point link If one port is configured as a full duplex and the other port is left in auto negotiation mode the second port will end up in half duplex because ports configured as half or full duplex do not negotiate Figure A 2 Full Half Duplex Mismatch In the above example port 1 on B is configured as a full duplex port and ...

Page 189: ...l Link Unidirectional links can be caused by an undetected failure in one side of a fiber cable or a problem with a ports transceiver Any failure that allows a link to remain up while providing one way communication is very dangerous for STP Figure A 3 After Applying STP In this example port 2 on B can receive but not transmit packets Port 2 on C should be in the blocking state but since it can no...

Page 190: ...uced Resource Errors The VH 2402 L3 Layer 3 switch performs its switching and routing functions primarily in hardware using specialized ASICs STP is implemented in software and is thus reliant upon the speed of the CPU and other factors to converge If the CPU is over utilized it is possible that BPDUs may not be sent in a timely fashion STP is generally not very CPU intensive and is given priority...

Page 191: ...isable all of the ports that provide redundant links Disabling ports one at a time and then checking for a restoration of the user s connectivity will identify the link that is causing the problem if time allows Connectivity will be restored immediately after disabling a data loop Avoiding Trouble Know where the root is located Although the STP can elect a root bridge a well designed network will ...

Page 192: ...ting the number of blocked ports help to limit the risk of an inappropriate transition Figure A 4 STP Network Layout This is a common network design The switches C and D have redundant links to the backbone switches A and B using trunks Trunks by default carry all the VLAN traffic from VLAN 1 and VLAN 2 So switch C is not only receiving traffic for VLAN 1 but it is also receiving unnecessary broad...

Page 193: ...definitions are extended to switches A and B This gives only a single blocked port per VLAN and allows the removal of all redundant links by removing switch A or B from the network Impact of Layer 3 Switching The IP routing operational mode of the VH 2402 L3 Layer 3 switch can accomplish the following Building a forwarding table and exchanging information with its peers using routing protocols ...

Page 194: ...op and creating an additional segment of the network Figure A 6 Using Layer 3 VLANs Using layer 3 switches and IP routing eliminates the need for STP port blocking because the packets are routed by destination addresses The link redundancy remains and relying on the routing protocols gives a faster convergence than with STP The drawback is that the introduction of layer 3 switching usually require...

Page 195: ... 1 then the result is 1 otherwise the result is 0 0 1 0 0 0 1 0 1 OR The logical OR operation compares 2 bits and if either or both bits are 1 then the result is 1 otherwise the result is 0 0 1 0 0 0 1 0 1 XOR The logical XOR exclusive OR operation compares 2 bits and if exactly one of them is a 1 then the result is 1 otherwise the result is 0 0 1 0 0 1 1 1 0 NOT ...

Page 196: ...2 L3 Management Guide 9033691 01 The logical NOT operation simply changes the value of a single bit If it is a 1 the result is 0 if it is a 0 the result is 1 This operation is carried out on a single bit 0 1 1 0 ...

Page 197: ...IEEE 802 3u 100BASE TX Fast Ethernet IEEE 802 3z 1000BASE SX Gigabit Ethernet IEEE 802 1 P Q VLAN IEEE 802 3x Full duplex Flow Control ANSI IEEE 802 3 Auto negotiation Protocols CSMA CD Data Transfer Rates Ethernet Fast Ethernet Gigabit Ethernet Half duplex Full duplex 10 Mbps 20Mbps 100Mbps 200Mbps n a 2000Mbps Topology Star ...

Page 198: ...Ethernet optional Physical and Environmental AC inputs 100 240 VAC 50 60 Hz internal universal power supply Power Consumption 40 watts maximum DC fans 3 built in 40 x 40 x10 mm fan Operating Temperature 0 to 50 degrees Celsius Storage Temperature 25 to 55 degrees Celsius Humidity Operating 5 to 95 RH non condensing Storage 0 to 95 RH non condensing Dimensions 441 mm x 207 mm x 44 mm 1U 19 inch rac...

Page 199: ...ce Transmission Method Store and forward RAM Buffer 16 MB per device Filtering Address Table 8K MAC address per device Packet Filtering Forwarding Rate Full wire speed for all connections 148 800 pps per port for 100Mbps 1 488 000 pps per port for 1000Mbps MAC Address Learning Automatic update Forwarding Table Age Time Max age 10 9999 seconds Default 300 ...

Page 200: ...Humidity 190 I IEEE 802 1Q tagging 130 IEEE 802 1Q VLANs 130 Illustration of STA 125 Ingress port 130 135 IP Configuration 18 L load balancing 129 log in 12 Logging on 5 M MAC address filtering 118 MAC Address Learning 191 MAC based VLANs 130 Main Menu 7 8 11 12 Management Information Base MIB 115 master port 127 Max Age 77 78 125 MIB 115 MIB objects 115 MIB II 115 MIBs 115 N Network Classes Class...

Page 201: ...6 Transmission Methods 191 Trap managers 114 Trap Type Authentication Failure 115 Broadcast Storm 115 Cold Start 114 Link Change Event 115 115 Port Partition 115 Topology Change 115 Warm Start 114 Traps 114 trunk group 127 U unauthorized users 5 untagging 130 Untagging 130 User Accounts Management 13 V View Delete User Accounts 14 VLAN 118 VT100 compatible terminal 4 W Weight 190 ...

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