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Reference.bok : Chapter10    101  Wed Apr 22 10:58:08 1998

101

How Bridging Works

WAN Bridging Services

Forwarding tables used

Bridged packets are processed by all the Forwarding Tables before being for-
warded. A packet which is allowed to pass by one Forwarding Table can therefore
be rejected by another Forwarding Table.

Operation of the Bridge in the Intel Express 8100 Router

Loop-Back check

When a packet is received for bridging, a check is performed to determine if the
packet was bridged to the network segment by the router itself—this is called a
“loop-back” check. Packets are discarded if they are received on the same link
that they were transmitted.

Forwarding

A packet which is not discarded by the loop-back check is checked against the
Forwarding Tables (as described in the previous section) to find out which net-
work segment(s) it should be transmitted. The packet is forwarded on the link(s)
allowed by the Forwarding Tables except the link from which it was received.

Содержание ER8100STUS - Express 8100 Router

Страница 1: ...Intel Express 8100 Router Reference Manual...

Страница 2: ...o OR 97124 6497 Intel Corporation assumes no responsibility for errors or omissions in this manual Nor does Intel make any commitment to update the infor mation contained herein Other product and corp...

Страница 3: ...the Password Authentication Protocol PAP 15 3 Frame Relay Services 17 4 ISDN Services 20 Integrated Services Digital Network ISDN in the Intel Express 8100 Router 20 ISDN Concept 21 ISDN Services 22...

Страница 4: ...Novell Routing Concept 71 Internetworking Packet Exchange IPX 72 Frame Types 72 Novell Addressing 72 Novell Metrics 73 Data Transmission 75 IPX over WAN Links 76 IPX WAN Protocol 76 IPX Watchdog Packe...

Страница 5: ...press 8100 Router 111 Bridge Spoofing 114 BPDU Spoofing 114 Non BPDU Spoofing 115 Enabling Bridge Spoofing 115 Appendices A Protocol Bandwidth Overheads and Requirements 117 B TCP and UDP Port Numbers...

Страница 6: ...terminating Equipment DE Discard Eligibility DLCI Data Link Connection Identifier DLCMI Data Link Connection Management Interface also called LMI DN Directory Number DTE Data Terminal Equipment DVMRP...

Страница 7: ...le Network Management Protocol SPX Sequenced Packet Exchange SVC Switched Virtual Circuit TCP Transmission Control Protocol TFTP Trivial File Transfer Protocol UDP User Data Protocol WAN Wide Area Net...

Страница 8: ...nternet Protocol SLIP RFC 1055 Routing Information Protocol RIP RFC 1058 Simple Network Management Protocol SNMP RFC 1155 Internet Numbers RFC 1166 Concise MIB Definitions RFC 1212 Management Informat...

Страница 9: ...over Integrated Services Digital Networks IS DN RFC 1618 Network Address Translation NAT RFC 1631 Bridge Control Protocol BCP for the Point to Point Protocol PPP RFC 1638 Link Control Protocol LCP for...

Страница 10: ...yer Protocol for Data Terminal Equipment DTE ISO IEC 8208 Frame Relay User Network Interface January 1992 FRF 1 Frame Relay Multiprotocol Interconnect December 1992 FRF 3 Media Access Control MAC Brid...

Страница 11: ...t 1993 ITU T CCITT Recommendation Q 850 ISDN User Network Interface Data Link Layer Specification 1993 ITU T CCITT Recommendation Q 921 ISDN Data Link Layer Specification for Frame Mode Bearer Service...

Страница 12: ...Part I LAN and WAN Links and Services...

Страница 13: ...rent WAN services available in the Intel Express 8100 Router are de scribed in the following chapters LAN Services Introduction Local Area Networks LAN are concerned with the interconnection of distri...

Страница 14: ...in a bus network It uses a base band single channel communication technique providing for a raw data transmission rate of either 10 Mbps for 10Base T or 100Mbps for 100Base T Ethernet uses carrier sen...

Страница 15: ...ts up to 5 WAN links Frame Relay ISDN or X 25 Leased lines A leased line is a permanent physical connection between two Local Area Net works The costs for the use of a leased line are fixed that is th...

Страница 16: ...ssary Routing protocols such as RIP and IPX send various routing packets between de vices to continually assess the topology of the network If the standard settings are used for these settings for exa...

Страница 17: ...1476 LAN 2 LAN 1 Primary WAN Link Backup WAN Link dial up Router A Router B LAN WAN 1 WAN 2 System Intel Express Router 9200 LAN WAN 1 WAN 2 System Intel Express Router 9200 1475 The Backup WAN Link m...

Страница 18: ...on For each link access can be blocked for outgoing access from the router to the WAN link for both outgoing and incoming access WAN link disabled outside the times defined in the timer profile For ex...

Страница 19: ...the Up for both call directions state for the configured time period within a day midnight to midnight That is the activity counter is incremented for both incoming and outgoing calls on the links If...

Страница 20: ...s main function is to es tablish a synchronous link connection between routers from any manufacturer PPP functions include encapsulating multi protocol datagrams establishing configuring and testing t...

Страница 21: ...k Control Protocol LCP The LCP takes care of the link connection Challenge Handshake Authentication Protocol CHAP The Challenge Handshake Authentication Protocol CHAP is available to offer security en...

Страница 22: ...r PPP ISDN links where the costs of oper ation of the link can be transferred a specific location For example if someone working from home needs an occasional connection to the office the costs of ope...

Страница 23: ...the Compression Con trol Protocol CCP and use the same compression algorithm Data compression is negotiated by the CCP whenever the link is established If the device over the PPP link does not suppor...

Страница 24: ...Mbps which may cause delays on combined link speeds above this for example on a 2 0 Mbps links Encryption and compression Data encryption can be used together with data compression see Data Com pressi...

Страница 25: ...the global list can be used in reply to CHAP requests from peers on any of the PPP links to the router The passwords in the local list can only be used for peers on the PPP link for which they are de...

Страница 26: ...ated Device 2 over the PPP link Device 1 also stores a copy of the random text file which is encrypted using the password defined for CHAP requests on the link Password 1 2 The device receiving the ra...

Страница 27: ...re never transmitted directly over the PPP link and therefore cannot be intercepted and used by unauthorized sources PAP uses simple password protection where the password is transmitted directly over...

Страница 28: ...Express 8100 Router authenticates the peer over the PPP link whenever the link is established For on demand switched PPP links including ISDN links the router authenticates the peer whenever the link...

Страница 29: ...psulated according to the Multiprotocol Encapsu lation Implementation Agreements of the Frame Relay Forum It provides effi cient network services and accommodates burst intensive applications over wid...

Страница 30: ...d by signalling protocols defined by the Frame Relay standards committees These signalling protocols perform the fol lowing tasks providing a heartbeat or keep alive message exchange to ensure that li...

Страница 31: ...by an unauthorized source Note Data encryption is only available in certain models of the Intel Express 8100 Router which are not available in some countries Data encryption over Frame Relay links use...

Страница 32: ...line and dial up switched links An overview of PPP and the facilities available is given in Chapter 2 Leased Lines Links p 8 ISDN links For the ISDN Intel Express 8100 Routers it is possible to confi...

Страница 33: ...he router can be connected directly to the ISDN Channel types There are two types of channels used in ISDNs B channels 64 kbps or 56 kbps full duplex synchronous channels for data and voice transfer D...

Страница 34: ...cost effective to pay for an end to end channel for the duration of the call In this case data is sent in packets and the cost is based partly on the volume of traffic rather than the duration of the...

Страница 35: ...g UUS Allows you to send or receive a limited amount of information to or from another station over the D channel in association with an existing call Calling Line Identification Presentation CLIP The...

Страница 36: ...works ISDNs uses Directory Numbers DNs to identify subscribers The International Telegraph and Telephone Consultative Committee CCITT a numbering plan for ISDN Recommendation E164 which specifies how...

Страница 37: ...router accepts the call when both the destination and source address checks succeed Address checking To ensure a one to one relationship between end devices a unique ISDN number is assigned to each li...

Страница 38: ...N networks do not provide presentation of the source address in incoming calls In these cases the router omits the check of the source address and accepts the calls there is no security check on these...

Страница 39: ...each terminal This is the most flexible form of terminal identification Each terminal on a line is given one or more identifiers each of which is a unique string of characters of your choice Each of...

Страница 40: ...alling No signalling or dialing is required for Permanent ISDN connections Permanent ISDN links operate on Layer 1 only Layer 2 and Layer 3 are not used by Per manent ISDN Permanent ISDN link types av...

Страница 41: ...tion is similar in the USA a similar state of affairs exists resulting in the National ISDN 1 standard ISDN protocol variants supported A number of country specific variants of ISDN are currently in u...

Страница 42: ...connect to the ISDN Reference points R S and T are connections between functional groups The Intel Express 8100 Router with an ISDN S T port contains the following physical interfaces The Intel Expre...

Страница 43: ...lexing and switching TE1 2 Terminal Equipment TE1 has an ISDN interface and terminates an ISDN call TE2 is similar to TE1 but does not conform to ISDN recommendations TA Terminal Adapter not required...

Страница 44: ...t switched data network can be either a Public Data Network PDN or a privately owned network X 25 is independent of the internal protocols used within the Packet Switched Data Network PSDN X 25 uses t...

Страница 45: ...al layer Link layer The primary responsibility of the link layer protocol is to ensure the error free ex change of data over a link which has variable delays The X 25 standard defines the use of eithe...

Страница 46: ...is analogous to a leased line WAN link Logical channels X 25 uses logical channels when communicating over PSDNs This means that a number of logical links connections to different remote destinations...

Страница 47: ...o the local DCE on the highest free Logical Channel Identifier it has available for outgoing calls The Call Request Packet contains the address of the remote DTE 2 The PSDN decides if the call is vali...

Страница 48: ...f 128 bytes and a window size of 2 packets For SVCs some X 25 networks allow negotiation of the packet and window sizes between the DTE and the DCE The packet and window sizes used are arrived upon us...

Страница 49: ...capsulation IP packets are encapsulated according to RFC 1356 and are identified using a Hex CC in the header RFC 1356 also allows SNAP encapsulation of IP packets which is not sup ported by the Intel...

Страница 50: ...git X 121 number and in some countries it can be used for sub addressing within the International Data Number for addressing a number of devices nodes located at a single Interna tional Data Number Th...

Страница 51: ...sts of the slave links that make up the Multilink The master link is the controlling link between the two sites and controls for example when the multilink is established or not data encryption over t...

Страница 52: ...time that the link is in use Bandwidth on Demand can only be done when a slave link is a dial up switched link such as ISDN B channels Leased line PPP links can only be stat ically allocated that is t...

Страница 53: ...ly when transmitting data over long distances The throughput of the Internet Tunnel is dependent on the Internet so can be quite slow at certain times of the day Note It is strongly recommended that y...

Страница 54: ...et Tunnel Site Access Security Access security must be considered when using Internet Tunnels This can be achieved using IP filtering to eliminate unauthorized traffic from the link Hiding your intern...

Страница 55: ...P data encryption CHAP and PAP on the X 25 links To establish a tunnel over an X 25 link the X 25 link is set up as normal together with an Internet Tunnel to the IP address of the remote router over...

Страница 56: ...ic Routes p 68 Routing and bridging for data over the link are then configured on the Internet Tunnel X 25 port WAN port configured for X 25 X 25 link PVC or SVC Up to 2 links Static IP route to the I...

Страница 57: ...Part II IP Novell IPX and Bridging Services...

Страница 58: ......

Страница 59: ...ology and the protocols used in IP environments References See the Preface for a list of Requests for Comments RFCs concerning IP rout ing Address assignment An IP address consists of a network part a...

Страница 60: ...host part They are di vided into different address classes which differ in the number of bits allocated to the network part and the hosts part local address of the address The value of the first octet...

Страница 61: ...dressing scheme and the limited number of IP address es impose limitations on network complexity Therefore subnetting has been in troduced What is subnetting Subnetting is the process of dividing an I...

Страница 62: ...s like this Decimal Notation 16 1 0 1 AND 255 255 192 0 16 1 0 0 Hexadecimal Notation 0x10010001 AND 0xffffc000 0x10010000 Subnet masks A subnet mask specifies which part of the host s address is used...

Страница 63: ...ve just been switched on and added to the network When the Intel Express 8100 Router receives an IP data packet which has to be transmitted to a local un Address bit no Subnet Mask 7 6 5 4 3 2 1 0 hex...

Страница 64: ...ge Protocol PING function IP Packet InterNet Groper function ICMP protocol The ICMP Internet Control Message Protocol is a protocol that focuses on con trol and management of IP connections ICMP messa...

Страница 65: ...ts must be allowed to pass by the filters Transmit and receive filters Filters are defined on a link basis and separate filters are implemented for trans mitting for restricting IP packets leaving the...

Страница 66: ...r example FTP control TFTP SNMP a range of ports or all ports Up to 50 IP filters can be defined for all the IP links References for Firewall Protection Defining filters for firewall protection to ens...

Страница 67: ...ld therefore only be enabled when required when troubleshooting or when an attack is suspected For packets which are logged the packet details are recorded in the System Log for the router which cabn...

Страница 68: ...a TELNET Server source port and a destination port of greater than 1023 unassigned ports used by TELNET Client Direction Flags Source Add Source Port Dest Dest Port Comments 1 2 ACK 0 Host 1 X Host 2...

Страница 69: ...Introduction to NAT Network Address Translation NAT can be used to translate local internal IP network addresses to remote external IP addresses used by devices outside the internal network For exampl...

Страница 70: ...a subnet address or an individual IP address For packets from the router addresses matching entries in the internal list are translated to the associated external addresses For packets from the remot...

Страница 71: ...ne NAT translation tables for the LAN link but it may be con fusing to think of the LAN as an external network NAT on the LAN link works in exactly the same way as for the WAN links NAT and IP filteri...

Страница 72: ...mply converted to the corresponding external addresses This can be used when Dynamic Mapping is being used to make internal net work devices accessible to the external network Dynamic Mapping Dynamic...

Страница 73: ...using Dynamic Mapping When using Dynamic Mapping only internal devices can initiate communica tions with external devices Internal addresses are unknown to the external net work and a translation addr...

Страница 74: ...a fixed translation address to an internal de vice address so that communications can also be initiated to the device from the external network Examples of Use Simple address translation A common app...

Страница 75: ...the two networks see the following example Translation table entries For the above example the entries required in the NAT table are Entry 1 Mapping Static Internal Address 10 0 0 0 Internal Mask 255...

Страница 76: ...outer for 180 seconds or more it marks the routes served by the adjacent router as unusable RIP 1 and RIP 2 standards The Intel Express 8100 Router supports both RIP 1 and RIP 2 RIP 1 is the orig inal...

Страница 77: ...is ten to them Subnet hiding is only done when sending routing updates on num bered links subnetworks are sum marized by routers No subnet hiding is done This results in larger routing tables as all s...

Страница 78: ...down the 64 kbps link is used Example of metrics used incorrectly The following example indicates how an inappropriate use of metrics may result in ineffective use of the available bandwidth Here dat...

Страница 79: ...when a network topology change is detected Triggered RIP therefore minimizes the use of WAN links for the exchange of routing information Multiple paths for triggered RIP For devices using standard RI...

Страница 80: ...or data transfers This can be particularly useful for slow WAN links which could be swamped by the RIP updates Using static routing to eliminate RIP is only practical for connecting to a few remote ne...

Страница 81: ...oating so if another route with lower metric to the destination network is available the route with the lowest metrics is taken Static routes and the RIP metrics The metric used for static routes is a...

Страница 82: ...nets 17 0 0 0 75 0 0 0 126 0 0 0 via Router X must be created for both routers 1 and 2 Routers 1 and 2 then announce these static routes via RIP meaning that the route to the internetworks 17 0 0 0 75...

Страница 83: ...IP Novell IPX calculates the best route to a destination based upon routing time de lays associated with the links and with the number of hops intermediate routers taken to reach a network Background...

Страница 84: ...version of the Novell operating system Novell Addressing Address notation The Novell IPX hexadecimal address notation consists of a 4 byte network num ber followed by the 6 byte node ID MAC address a...

Страница 85: ...Novell metrics use the following to calcu late the best routes Delays Ticks The delay is the time associated with sending data via a route that is if alterna tive routes are available the data packet...

Страница 86: ...ing RIP and SAP and reading the metrics from the routing and service table for the router see Establishing static routes and static services in Static Routes and Servic es p 90 However in some cases t...

Страница 87: ...on the Local Area Network LAN 2 All local routers with a path to the destination address send a routing response to the querying workstation 3 The NetWare device selects the best path and sends the da...

Страница 88: ...ks a numbered link should be used IPX WAN Protocol The IPX WAN Protocol can be selected for communicating over WAN links to ensure consistency with the configuration of the router on the other end of...

Страница 89: ...e routers If it succeeds it informs the Slave of the protocol selected If a numbered link is selected during negotiation the Master also informs the Slave of the network number assigned to the link en...

Страница 90: ...ating over the link the link may never get the chance to become inactive and so the operating costs can be high In addition if the link is brought down for some other reason the client sessions may be...

Страница 91: ...Discarded by the Intel Express 8100 Router As IPX Serialization Packets are sent by NetWare servers at regular intervals and do not allow dial up switched WAN links to become inactive the operat ing...

Страница 92: ...ep alive packets can be sent by all the network devices in the session SPX Keep alive packets over WAN links As with IPX watchdog packets SPX keep alive packets can cause problems when communicating o...

Страница 93: ...able SPX session timeout is initiated for each session which disables SPX spoofing after a defined time period Network devices must then respond to SPX keep alive packets as usual If the SPX session i...

Страница 94: ...ers are implemented for transmit for restricting IPX packets leaving the router on a link and receive for restricting IPX packets entering the router from a link Note A good understanding of IPX is re...

Страница 95: ...ice node can be filtered A Destination Node Address of 000000000000 disables filtering on the destination node ad dress Destination Socket IPX packets addresses to specific sockets can be discarded Th...

Страница 96: ...Filters Example Filter requirement NetWare devices use Diagnostic Request Packets to get information from about other reachable devices These packets can be used for testing if a device is reach able...

Страница 97: ...ocol RIP Routing Information Protocol RIP Routing information between routers is exchanged by means of the Routing In formation Protocol RIP initiating the following functions locates the fastest rout...

Страница 98: ...riggered update is routing information exchanged due to changes in the net work topology for example if a link fails Cost factor The costs for exchanging routing information on packet switched network...

Страница 99: ...mation about all the services available on the local network using SAP agents Workstations that require information about services available send a broadcast for example get nearest server The local S...

Страница 100: ...d to the router using the Routing Infor mation Protocol RIP Similarly a static service is a service which is always known to the router and does not need to be announced to the router using the Servic...

Страница 101: ...ary static route is not available and another route with a lower metric is not available A static backup route is only announced to other routers using RIP if it is in use by the router when it is in...

Страница 102: ...rrect operation a static backup route must have a higher metric than the primary route If the primary route is a dynamic route using RIP the metrics for the route are calculated automatically by the r...

Страница 103: ...over the WAN link This eliminates all routing traffic from the WAN link optimising the available band width for data transfers However establishing static routes and services is only practical if rela...

Страница 104: ...hed WAN links are be initiated just to send IPX watchdog packets and SPX keep alive packets to remote clients Cost reductions using RIP and SAP filtering This cost reduced WAN example can be further i...

Страница 105: ...bridging services so that the router can also act as a bridge Bridging concept Bridging in the router conforms to the following standards IEEE 802 1D Local MAC Bridging IEEE 802 1G Remote MAC Bridgin...

Страница 106: ...back check is implemented in this router to ensure that packets transmit ted received back on the same link are discarded This feature stops loop backs in the network segments for example if a WAN lin...

Страница 107: ...e forwarding tables are transmitted to all the network segments except the one from which it was received Alternatively the bridge can be set up to discard packets which do not appear in the forwardin...

Страница 108: ...Destination Forwarding Table example Notes For entries in the Unicast Destination Forwarding Table the incoming link can only be All that is packets having the defined Unicast MAC destina tion address...

Страница 109: ...earned entries are automatically put into the Unicast Destina tion Forwarding Table and allow the bridge to forward packets to the specific network segment towards the Destination MAC address Bridge l...

Страница 110: ...re rejected 0180C2000003 IEEE 802 1D demands that they are rejected 0180C2000004 IEEE 802 1D demands that they are rejected 0180C2000005 IEEE 802 1D demands that they are rejected 0180C2000006 IEEE 80...

Страница 111: ...he router Up to 62 entries can be defined Default bridge action from unknown sources The bridge can be set up to either forward to all links default or discard Multi cast packets from source addresses...

Страница 112: ...For entries in the Type Forwarding Table the incoming link can only be All when the outgoing link is None The Type Forwarding Table can only contain static entries defined by the oper ator during conf...

Страница 113: ...ed for bridging a check is performed to determine if the packet was bridged to the network segment by the router itself this is called a loop back check Packets are discarded if they are received on t...

Страница 114: ...passed to the Source Forwarding Table for further processing Note If a table entry for the packet defines the outgoing link as None the packet is discarded 2 If a table entry exists for the Multicast...

Страница 115: ...packet is not found in the table the packet is discarded 4 If no entry is found for the Source MAC address and the Default Action of the Source Forwarding Table is set to Pass the packet is labelled f...

Страница 116: ...st Destination Forwarding Table see Destination Forwarding Tables in Forwarding Tables p 96 An entry is found in the table for a destination MAC address of 000080000001 All incoming links are always u...

Страница 117: ...111111 and the incoming link as the LAN link One of the entries defines the outgoing link as WAN link 1 the other defines the outgoing link as WAN link 2 The packet is therefore labelled for forwardin...

Страница 118: ...diagram represents the data forwarded unshaded area of the total number of packets received for bridging Controlled bridging The Intel Express 8100 Router allows packets which do not appear in the for...

Страница 119: ...ged data traffic over expensive WAN links Controlled bridging with bridge learning It is still possible to have controlled bridging with bridge learning enabled In this case the bridge still forwards...

Страница 120: ...wise the other router cannot learn remote destinations Spanning Tree Algorithm Bridging Loops Problem with conventional bridges The following figure shows a simple Local Area Network built up of 3 seg...

Страница 121: ...within the network segments indefinitely this is known as a bridging loop The receiver receives many copies of the same pack et A solution to this problem is described in the following section Spannin...

Страница 122: ...Bridges A and C which also creates a potential bridging loop However by using the Spanning Tree Algorithm Bridge B breaks the loop by blocking its path to segment 3 Bridge failure In the event that o...

Страница 123: ...hs to the different segments of the network Normal data is not transmitted Blocking The bridge enters the Blocking State if a path with higher priority is found to exist during the Listening State Nor...

Страница 124: ...a cost factor assigned to it which uses the Path Cost defined by the Path Cost parameter These parameters are used by the Spanning Tree Algorithm to determine the to pology of the bridged network Spa...

Страница 125: ...n BPDU packets to its neighboring bridges These Configuration BPDU messages contain information about the spanning tree topology The con tents of these packets only changes when the bridged network to...

Страница 126: ...m the bridged network the contents of Configuration BPDU packets sent between the bridges is the same The contents of these packets only changes when the bridged network topology changes To counteract...

Страница 127: ...U Spoofing Bridge Spoofing on a WAN link Another feature of Bridge Spoofing is when two bridge ports are connected via a WAN link and one port is in the Blocking State and the other is in the Forward...

Страница 128: ...Appendices...

Страница 129: ...nd bridge BPDU spoofing These are not accounted for in the calculation examples Bandwidths used by IP RIP The following table lists the bandwidth used by IP RIP IP RIP header included in every RIP pac...

Страница 130: ...s of link bandwidth For 100 IPX networks the IPX RIP protocol requires 115 bit s of link bandwidth and so on Example bandwidth usages for IPX SAP For 50 IPX services the IPX SAP protocol requires 460...

Страница 131: ...set to zero except the low order eight bits Port assignments The following table provides an extract of RFC 1700 of the most used port num bers low order eight bits of the port are specified Addition...

Страница 132: ...120 TCP and UDP Port Numbers 162 SNMP Trap UDP Simple Network Management Protocol Traps 520 RIP UDP Routing Information Protocol 2049 NFS UDP Network File Servers Decimal Keyword Protocol Description...

Страница 133: ...201 Xerox PUP Address Translation conflicts with IEEE 802 3 length field 0600 XNS Internet 0800 DoD Internet 0801 X 75 Internet 0802 NBS Internet 0803 ECMA Internet 0804 CHAOSNet proposed by Symbolic...

Страница 134: ...6003 DEC DECNet Phase IV 6004 DEC Local Area Transport LAT 6005 DEC DECNet Diagnostics 6006 DEC DECNet Customer Use 6007 DEC Local Area VAX Cluster LAVC 6008 DEC unassigned 6009 DEC unassigned 6010 60...

Страница 135: ...ssigned 803D DEC Ethernet CSMA CD Encryption Protocol 803E DEC unassigned 803F DEC LAN Traffic Monitor Protocol 8040 DEC unassigned 8041 DEC unassigned 8042 DEC unassigned 8044 Planning Research Corp...

Страница 136: ...d 80A3 Nixdorf Computers Germany 80A4 80B3 Siemens Gammasonics Inc 80C0 80C3 Digital Communications Assoc Inc DCA Data Exchange Cluster 80C4 Banyan VINES IP 80C5 Banyan VINES Echo 80C6 Pacer Software...

Страница 137: ...nik A S 8107 Symbolics Private 8108 Symbolics Private 8109 Symbolics Private 8130 Waterloo Microsystems Inc 8131 VG Laboratory Systems 8137 Novell NetWare IPX old 8138 Novell Inc 8139 813D KTI 9000 Lo...

Страница 138: ...der Version 4 bits Internet Header Length ILH 4 bits Type of service 1 byte Total length 2 bytes Identification 2 bytes Flags 3 bits Fragment offset 13 bits Time to live 1 byte Protocol 1 byte Header...

Страница 139: ...ket is as follows IPX Ethernet 802 3 header An IPX Ethernet 802 3 header looks like this IPX header 802 3 802 2 SNAP Ethernet Type Checksum 2 bytes FFFF Packet Length 2 bytes Transport Control 1 byte...

Страница 140: ...re present i e Route Control Broad cast etc source route bridging is used A Token Ring 802 2 header looks like this Destination Address 6 bytes Source Address 6 bytes Length 2 bytes DSAP 1 byte E0 SSA...

Страница 141: ...Token Ring 802 2 header looks like this Route Control Direction 1 byte Route Designator 1 2 bytes 2 bytes Route Designator n 2 bytes DSAP 1 byte E0 SSAP 1 byte E0 Control 1 byte 03 Access Control 1 by...

Страница 142: ...are currently known Service Object User 1 User Group 2 Print Queue 3 File Server 4 Job Server 5 Gateway 6 Print Server 7 Archive Queue 8 Archive Server 9 Job Queue A Administration B NAS SNA Gateway...

Страница 143: ...ity 72 TES Netware VMS 7a Emerald Backup 92 NetWare Access Server 98 Portable NetWare 9e PowerChute a1 Compaq IDA Status Monitor ac RSPX Server 107 CSA MUX 114 CSA LCA 115 CSA CM 116 CSA SMA 117 CSA D...

Страница 144: ...132 Novell IPX Service Types Compaq SNMP Agent 174 HP Laserjet 30c ARCserve 4 0 3c4 NW SQL 3de Sitelock 4808 Intel Netport Print Server 8002 WordPerfect Network v 8888 Wildcard FFFF Service Object...

Страница 145: ...g comparison 94 background knowledge required 93 Configuration BDPU messages 113 controlled 106 Destination Forwarding Tables description 96 Destination Forwarding Tables operation of 102 disabling br...

Страница 146: ...38 address check ISDN 25 Forwarding Tables bridging 96 Dial up switched links 3 Daily Activity Limit 7 Timecut mode 4 Disabling bridge learning 97 Documents related v Dotted decimal notation 48 Dynam...

Страница 147: ...sage Protocol ICMP 52 logging filtered packets 55 Network Address Translation NAT 57 network numbers 48 packet formats 126 packets filtered 53 Ping description 52 port number assignments 119 private n...

Страница 148: ...ns using RIP filtering 92 cost reductions using SAP filtering 92 data transmission process 75 Ethernet 802 2 header format 128 Ethernet 802 3 header format 127 Ethernet type header format 128 IPX WAN...

Страница 149: ...4 triggered 67 RIP Novell IPX 85 filtering 86 Rx filters 86 Tx filters 86 Routing and Bridging comparison 94 table Novell IPX 85 S SAP Novell IPX 72 agent 87 broadcasts 87 filtering 87 Rx filters 88 S...

Страница 150: ...25 Permanent PVC 34 Switched SVC 34 W WAN Bridging definition of 93 see Bridging WAN links Backup links 4 Dial up switched links 3 general facilities available 3 Leased lines 3 maximum number of 3 ty...

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