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8

GigaX2008EX L2 Managed Switch User Manual

Table 4. LED indicators

No.

LED

Description

1

SYSTEM

Solid green indicates that the device is turned on. If this light 

is off, make sure the power cord is attached to the switch and 

plugged into a power source

2

10/100 port 

STATUS

Solid green indicates that link is present on the port; flashing 

means the attached device is sending or receiving data

3

10/100 port 

PoE

Solid green indicates that a Power Device (PD) is connected

4

GIGABIT 

port STATUS

Solid green indicates that link is present; flashing means data is 

being transmitted; if the LED is off, no device is connected

5

GIGABIT 

port SPEED

Solid green means the link speed is 1000Mbps, solid amber 

means 100Mbps; if the LED is off, the port speed is 10Mbps 

6

FAN

Solid green indicates that the system fan works properly

3.3 

Part 3 — Basic switch setting for management

After completing the hardware connections, configure the basic settings for your 

switch. You can manage the switch using the following methods:

•  Web interface: the switch has a set of pages to allow to you manage it using 

Java

®

-enabled IE5.0 or higher version.

•  Command Line Interface: use console port to manage the switch.

3.3.1  Setting up through the console port

1. Use the supplied crossover RS-232 cable to connect to the console port on 

the front panel of the switch. This port is a male DB-9 connector, implemented 

as data terminal equipment (DTE) connection. Tighten the retaining screws 

on the cable to secure it on the connector. Connect the other end of the cable 

to a PC running terminal emulation software. e.g. Hyper Terminal.

2. Make sure the settings of your terminal emulation software as follows:

a) Choose the appropriate serial port number

b) Set the data baud rate to 9600

c) Set the data format to no parity, 8 data bits and 1 stop bit

d) No flow control

e) Set VT1000 for emulation mode

3. After setting up the terminal, you can see the prompt “(ASUS)%” on the 

terminal.

4. Type “login” to access the command line interface. The default user name is 

Содержание GigaX 2008EX

Страница 1: ...GigaX 2008EX User Manual Layer 2 Managed Switch ...

Страница 2: ...hantability or fitness for a particular purpose In no event shall ASUS its directors officers employees or agents be liable for any indirect special incidental or consequential damages including damages for loss of profits loss of business loss of use or data interruption of business and the like even if ASUS has been advised of the possibility of such damages arising from any defect or error in th...

Страница 3: ...ful interference to radio or television reception which can be determined by turning the equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures Reorient or relocate the receiving antenna Increase the separation between the equipment and receiver Connect the equipment to an outlet on a circuit different from that to which the receiver...

Страница 4: ...e Fremont CA94538 USA General Fax 1 502 933 8713 General Email tmd1 asus com Web Site usa asus com Technical Support Support Fax 1 502 933 8713 General Support 1 502 995 0883 Notebook Support 1 510 739 3777 x5110 Support Email tsd asus com ASUS COMPUTER GmbH Germany and Austria Address Harkort Str 25 D 40880 Ratingen BRD Germany General Fax 49 2102 9599 31 General Email sales asuscom de for market...

Страница 5: ...t 1 Install the hardware 6 3 1 1 Install the switch on a flat surface 6 3 1 2 Mount the switch on a rack 6 3 2 Part 2 Set up the switch 6 3 2 1 Connect the console port 6 3 2 2 Connect to the computers or a LAN 7 3 2 3 Attach the power adapter 7 3 3 Part 3 Basic switch setting for management 8 3 3 1 Setting up through the console port 8 3 3 2 Setting up through the Web interface 9 4 Management with...

Страница 6: ...19 4 5 3 Traffic Control 20 4 5 4 Dynamic Addresses 20 4 5 5 Static Addresses 21 4 5 6 Tagged VLAN 22 4 5 7 Default Port VLAN and CoS 23 4 5 8 CoS Queue Mapping 23 4 6 SNMP 25 4 6 1 Community Table 25 4 6 2 Host Table 25 4 6 3 Trap Setting 26 4 7 Security 27 4 7 1 Port Access Control 27 4 7 2 Dial In User 28 4 7 3 RADIUS 29 4 8 Power over Ethernet PoE 29 4 9 Cable diagnosis 30 4 10 Statistics Chart...

Страница 7: ...36 5 3 1 System Commands 37 5 3 2 Physical Interface Commands 39 5 3 3 Bridge Commands 39 5 3 4 SNMP 43 5 3 5 Security Commands 45 5 3 6 PoE 47 5 4 Miscellaneous Commands 49 6 IP Addresses Network Masks and Subnets 50 6 1 IP Addresses 50 6 1 1 Structure of an IP address 50 6 1 2 Network classes 51 6 2 Subnet masks 51 7 Troubleshooting 53 7 1 Diagnosing problems using IP utilities 53 7 1 1 ping 53 ...

Страница 8: ...reen 11 Figure 9 Home page 12 Figure 10 Top frame 12 Figure 11 Expanded menu list 13 Figure 12 Management 15 Figure 13 IP Setup 15 Figure 14 Administration 16 Figure 15 Reboot 16 Figure 16 Firmware upgrade 17 Figure 17 Physical interface 17 Figure 18 Link aggregation 19 Figure 19 Mirroring page 19 Figure 20 Traffic control 20 Figure 21 Dynamic address 20 Figure 22 Static address 21 Figure 23 Tagged...

Страница 9: ...igure 37 Save configuration 33 Figure 38 CLI interface 34 Figure 39 Boot ROM command mode 35 Figure 40 System commands 37 Figure 41 Using the ping utility 53 Figure 42 Using the nslookup utility 54 List of tables Table 1 Front panel labels and LEDs 4 Table 2 Rear panel labels 5 Table 3 Technical specifications 5 Table 4 LED indicators 8 Table 5 Port color description 13 Table 6 Commonly used buttons...

Страница 10: ...vi GigaX2008EX L2 Managed Switch User Manual ...

Страница 11: ...r SFP Gigabit interface converter GBIC slots Automatic MDI MDIX support for 10 100Base TX and 10 100 1000Base T ports 8K MAC address cache with hardware assisted aging 802 3x flow control 802 1Q based tagged VLAN up to 256 VLANs 802 1p class of service 4 queues per port 802 3ad link aggregation manual up to 15 trunk groups Port Mirroring 802 1x port based network access control RADIUS remote authen...

Страница 12: ...y Boldface type text is used for items you select from menus and drop down lists and text strings you type when prompted by the program 1 2 3 Symbols This document uses the following icons to call your attention to specific instructions or explanations Note Provides clarification or additional information on the current topic Definition Explains terms or acronyms that may be unfamiliar to many read...

Страница 13: ...ith the following items GigaX2008EX 10 port L2 managed switch AC Power cord Null modem cable for console interface DB9 Rack installation kit two brackets with six 6 32 screws Installation CD ROM User Manual Quick installation guide Figure 1 GigaX2008EX L2 managed switch package contents 12 SYSTEM RPS FAN CONS OLE RS 23 2 8 4 2 1 7 5 3 6 ...

Страница 14: ...e or voltage OFF No power FAN Green ON The fan is working properly Amber ON The fan stops PoE Green ON PD Powered Devices is connected and ready to provide power Flashing PoE is off due to a fault on the port OFF PD is not connected or not a valid power device 10 100 port status Green ON Link is present at 100Mbps Flashing Transmitting data Amber ON Link is present at 10Mbps Flashing Transmitting ...

Страница 15: ... FAN System fan 2 4 Technical specifications Table 3 Technical specifications Physical Dimensions 43 5mm H x 444mm W x 265mm D Power Input Consumption 100 240V AC 2 5A 50 60Hz 90 watts Environmental Ranges Operating Storage Temperature 10 to 50 C 14 to 122 F 40 to 70 C 40 to 158 F Humidity 15 to 90 0 to 95 Altitude up to 10 000ft 3 000m 40 000ft 12 000m System Fan Dimensions Voltage and Current Spee...

Страница 16: ...e hardware Connect the device to the power outlet and your computer or network 3 1 1 Install the switch on a flat surface The switch should be installed on a level surface that can support the weight of the switches and their accessories Attach four rubber pads on the marked location on the bottom of the switch 3 1 2 Mount the switch on a rack 1 Attach brackets to each side of the switch and make t...

Страница 17: ...wise the link speed can not reach 1Gbps 3 2 3 Attach the power adapter 1 Connect the AC power cord to the power receptacle on the back of the switch and plug the other end of the power cord into a wall outlet or a power strip 2 Check the front LED indicators with the description in Table 4 If the LEDs light up as described the switch hardware is working properly Figure 4 Overview of hardware conne...

Страница 18: ...tions configure the basic settings for your switch You can manage the switch using the following methods Web interface the switch has a set of pages to allow to you manage it using Java enabled IE5 0 or higher version Command Line Interface use console port to manage the switch 3 3 1 Setting up through the console port 1 Use the supplied crossover RS 232 cable to connect to the console port on the ...

Страница 19: ... 0 0 0 0 1 as your default route entry as shown in Figure 5 Figure 5 Login and IP setup screen 3 3 2 Setting up through the Web interface To successfully connect your PC to the switch your PC must a valid IP in your network Contact your network administrator to obtain a valid IP for the switch If you wish to change the default IP address of the switch follow section 3 3 1 to change the IP address ...

Страница 20: ...t any time see section 5 3 1 System Commands 3 To setup a new IP address click System then IP Setup see Figure 7 Fill in the IP address network mask and default gateway then click OK 4 If your new address is different from the default the browser cannot update the switch status window or retrieve any page This is normal You have to retype the new IP address in the address location box and press En...

Страница 21: ...pe the following in the web address or location box and press Enter http 192 168 1 1 This is the factory default IP address for the switch A login screen displays as shown in Figure 8 Figure 8 Configuration manager login screen Login is not required if you do not enable Web authentication access see 3 3 2 2 Enter your user name and password then click OK Use the following defaults the first time you...

Страница 22: ...es 10 This frame remains on the top of the browser window all the times and updates the LED status periodically See Table 4 for the LED definitions See Table 5 for the color status description Figure 10 Top frame Table 5 Port color description Port Color Description Green Ethernet link is established at 100Mbps Black No Ethernet link Amber Ethernet link is established at 10Mbps Clicking on the port...

Страница 23: ... 1 Menu navigation tips To expand a group of related menus click on the corresponding group name The sign will change to after expansion The left frame a menu frame as shown in Figure 11 contains all the features available for switch configuration These features are grouped into categories e g System Bridge etc You can click on any of these to display a specific configuration page ...

Страница 24: ...he existing configuration to the system e g a static MAC address rule Modifies an existing entry Deletes the selected item e g a static route and etc Re displays the current page with updated statistics or settings 4 3 System Pages System pages include management IP setup administration reboot and firmware update function 4 3 1 Management The Management page contains the following information Model N...

Страница 25: ...rface Network Mask Default Gateway To save any changes and make it effective immediately click OK Use Reload to refresh the setting as shown in Figure 13 Figure 13 IP setup 4 3 3 Administration The Administration page allows you enable or disable the authentication for web user by password protection The default setting for web access does not require any authentication To save any changes and mak...

Страница 26: ...ing information Hardware Version shows the hardware revision number Boot ROM Version shows the version of the boot code Firmware Version shows the current running firmware version This number will be updated after the firmware update Enter the firmware location into the firmware space directly or click Browse to choose the file name of the firmware from prompt window Click Upload to update the switch fir...

Страница 27: ...ollowing information for each port a Link status the link speed and duplex for an existing link otherwise link is down b Admin the setting value to disable or enable the port c Mode the setting value for link speed and duplex mode d Flow Control the setting value to enable or disable 802 3x flow control mechanism Select the corresponding port number and configure the port setting then click on the ...

Страница 28: ...s physically active Go to Physical Interface and check the link mode in the runtime status window for the trunk ports If all the trunk members are in the same speed and full duplex mode then the trunk group is set up successfully If one of the members is not in the same speed or full duplex mode the trunk is not set correctly Check the link partner and change the settings to have the same speed an...

Страница 29: ...mirror function for the selected group Monitor Port Receives the copies of all the traffics in the selected mirrored ports The monitor port can not belong to any link aggregation group The monitor port can not operate as a normal switch port It does not switch packets or do address learning The monitored egress packets will be untagged Click OK to make the setting send to the switch HTTP server Cli...

Страница 30: ...effective please go to Save Configuration page then click on Save You can look up MAC addresses by checking the port VLAN ID or and MAC address then click on Query The address window will display the result of the query Figure 21 Dynamic address 4 5 3 Traffic Control Traffic control prevents the switch bandwidth from flooding packets including broadcast packets multicast packets The limit number is ...

Страница 31: ...in the address window When you create more than 15 entries the new added entries will display in the next page You can click on First Previous Next or Last to go through the pages of static MAC address or input the page number and then click on Go You can remove the existed address by selecting the entry with the mouse then clicking on Remove The Modify button updates the existed MAC address entri...

Страница 32: ... more VLAN groups at the same time it will confuse the switch and cause flooding traffics To prevent it the switch only allows one untagged port belongs to one VLAN at the same time That is the untagged port belongs to the VLAN group which is called PVID and configured in the Default Port VLAN CoS page If you want to assign an untagged port from one VLAN to another you have to remove it from the orig...

Страница 33: ...ress queues for each port For each queue you can specify the scheduling types as follows Strict priority scheduling each CoS value can map into one of the four queues The queue 4 has the highest priority to transmit the packets And packets in the low priority queue do not transmit until all the high priority queues become empty In Strict priority scheduling weight settings are always zero Weighted...

Страница 34: ...ling low priority queues have the opportunity to send packets even through the high priority queues are not empty The fixed weights are 1 2 4 8 Click OK to save the configuration Click on Reload to refresh the settings to current value To make the configuration effective go to Save Configuration page then click Save Figure 25 Cos queue mapping ...

Страница 35: ... the privilege to make a setting write access by checking the box Click OK to save the configuration permanently or Reload to refresh the page Figure 26 Community table 4 6 2 Host Table This page links host IP address to the community name that is entered in Community Table page Type an IP address and select the community name from the drop down list Click OK to save the configuration permanently o...

Страница 36: ...p Setting By setting trap destination IP addresses and community names you can enable SNMP trap function to send trap packets in different versions v1 or v2 Click OK to save the configuration permanently or Reload to refresh the page Figure 28 Trap setting ...

Страница 37: ... port user see above Authentication Method RADIUS or Local database can be used to authenticate the port user Quiet Period If authentication failed either from RADIUS or local database the switch waits upon this time period before sending another authentication request to the port user Retransmission Time If the port user failed to respond to authentication request from the switch the switch waits...

Страница 38: ...alue Figure 29 Port Access Control 4 7 2 Dial In User Dial in User is used to define users in the local database of the switch User Name New user name Password Password for the new user Confirm Password Enter the password again Dynamic VLAN Specify the VLAN ID assigned to the 802 1x authenticated clients Please click Add to add the new user Click Modify when you have finished the modifications Click ...

Страница 39: ... Figure 31 RADIUS 4 8 Power over Ethernet PoE PoE provides a way to distribute low voltage power across the network using existing copper Ethernet cable to an endpoint PD Powered Device This centralized reliable source of power allows network devices such as IP telephones wireless LAN access points surveillance cameras and other embedded appliances to operate without additional power adapters or A...

Страница 40: ...e go to Save Configuration page and then click on Save You can look up the detailed port power information by selecting the port then click Query The port diagnostic window will display the result of the query Figure 32 Power over Ethernet 4 9 Cable diagnosis The major function of Cable Diagnosis is to detect cable fault open or short and report the estimated fault location Moreover Cable Diagnosis...

Страница 41: ...these charts Click Auto Refresh to set the period for retrieving new data from the switch You can differentiate the statistics or ports by selecting Color Finally click on Draw to let the browser to draw the graphic chart Each new Draw will reset the statistics display 4 10 1 Traffic Comparison This page shows the one statistics item for all the ports in one graphic chart Specify the statistics ite...

Страница 42: ...he discards or error counts for the specified port The data is updated periodically Figure 35 Error group 4 10 3 Historical Status You can display information for different ports and statistics items in this chart Since this shows the history of the statistics information the chart can keep the old data even it is refreshed Figure 36 Historical status ...

Страница 43: ...ective after a successful save Sometimes you may want to reset the switch configuration you can click on Restore to reset the configuration file to factory default Of course a system reboot will follow this restoration process You will lose all the configurations when you choose to restore the factory default configurations Figure 37 Save configuration ...

Страница 44: ...I mode after the timeout All the CLI commands are case sensitive In order to make them easier to use you can enter into different category by typing the full command then this category becomes your working category Thereafter you donʼt have to type sys before any sub commands For example sys is a command category including a lot of sub commands You donʼt have to type sys for the sub commands once ...

Страница 45: ...elpful in some situation we STRONGLY suggest users not to use them if you donʼt know the command function Figure 39 Boot ROM Command Mode 5 1 2 Boot ROM Commands Type in the boot mode to display the valid commands list Table 7 Boot ROM commands Command Parameters Usage a NONE Display MAC address b Slot 0 1 a Change boot slot c IP address Configure TFTP client IP address g NONE Load and execute firmw...

Страница 46: ...to do login again with authorized user name and password 5 3 CLI Commands The switch provides CLI commands for all managed functions The command uses are listed in the categories as the WEB management interface This way you can follow the instructions and set up the switch correctly as easily as using WEB interface to configure the switch save command is used to save the configuration to flash Some ...

Страница 47: ...in System Group and provides contact information on the managed node CLI command sys info contact system contact description If you put the contact description in the contact description field the switch contact information will be changed to the new one System Location Displays the physical location of the switch This is an RFC 1213 defined MIB object in System Group and provides the location info...

Страница 48: ... one or more routers CLI command net route static add destination subnet IP gateway netmask metric Password Protection is Enabled Disabled When the password protection is enabled the web interface will request a user name and password authentication while user accesses the switch through the browser CLI command sys web set enable disable New Password Verify Password The default user name is admin ...

Страница 49: ...le Displays the IEEE802 3x flow control setting of a port Note that this flow control is operating only in full duplex mode CLI command l2 port flow port number enable disable Reload Restores the previous port settings from the configuration file CLI command l2 port retrieve 5 3 3 Bridge Commands Show Trunk Displays a specific trunk group settings User can create a new trunk group by specify a unique tr...

Страница 50: ...ettings from configuration file CLI command l2 mirror retrieve Limit Rate User can limit the broadcast multicast and flooding due to destination lookup failed traffic rate by turning the traffic control on CLI command l2 rate set enable disable mode 1 broadcast only 2 broadcast and multicast 3 broadcast multicast and unknown unicast limit rate 70 250000 Kbps sec Reload Restores the previous saved setti...

Страница 51: ...med as unique entry in ARL table CLI command l2 arl delete mac address vlan id Reload Restores the previous saved settings from configuration file CLI command l2 arl retrieve Show VLAN Displays the existing VLAN information of the switch CLI command l2 vlan show vlan id Name VLAN ID Allows user to config the VLAN settings User may create a new VLAN by giving a unique VLAN ID a VLAN description name a...

Страница 52: ...ociated port member list CLI command l2 port vlan vlan id 4095 to disable the port based vlan port list CoS Value Sets the Class of Service for a port by assigning it a priority with range of 0 7 criteria value for untagged packets CLI command l2 port priority CoS port list Reload Restores the previous saved settings from configuration file CLI command l2 port retrieve CoS Map Allows user to map the...

Страница 53: ...ning its community string and privileges CLI command snmp community set Community entry table index entry id to config Community string old community string new community string This action will modify all hosts with community string from ʻold communityʼ to ʻnew communityʼ Are you sure y n y y for ʻyesʼ n for ʻnoʼ Get privileges y always turn on by default Set privileges y n n set privilege y for ʻ...

Страница 54: ...mmunity string Allows user to delete a host entry from host table CLI command snmp host delete Entry id table index entry id to delete Reload Restores the previous saved settings from configuration file CLI command snmp host retrieve Trap Version v1 v2c Destination Community for Trap A trap entry contains SNMP version currently support version 1 and version 2c a destination IP address and the remote...

Страница 55: ...and security dot1x bridge reauth enable disable Reauthentication Time Allows user to set up the reauthentication time CLI command security dot1x bridge reauthtime reauthentication time 1 4294967295 sec Authentication Method Allows user to set up the authentication method RADIUS or Local database CLI command security dot1x bridge authmeth type 1 local 2 radius Quiet Period Allows user to set up the...

Страница 56: ...x bridge port guestvlan vlan id 0 no guest vlan port list Reload Restores the previous saved settings from configuration file CLI command security dot1x retrieve User Name Password Confirm Password Dynamic VLAN Create users in the local database of the switch for 802 1x authentication A user entry contains a user name password and dynamic VLAN CLI command security dialinuser create User Name user nam...

Страница 57: ...RADIUS server IP server port and server key CLI command security radius set authentication server ip ip none old server ip new server ip authentication server port port default old server port new server port authentication server key key none server key confirm authentication key key none confirm server key Reload Restores the previous saved settings from configuration file CLI command security radiu...

Страница 58: ...ic result for port power CLI command poe diag display Display real time port power information CLI command poe display port list show Show the PoE configuration CLI command poe show save Save the PoE configuration into the flash CLI command poe save Reload Restores the previous saved settings from configuration file CLI command poe retrieve ...

Страница 59: ...ime settime sets the current time sys files config backup backup configuration files sys files config default restore factory default configuration files sys monitor auto enable or disable fan auto detection sys monitor set Set fan speed command 1 255 sys monitor show Show the status of system environment net ping ping remote host net route show displays the entries in the routing table ...

Страница 60: ...The IP address 20 56 0 211 is read twenty dot fifty six dot zero dot two eleven 6 1 1 Structure of an IP address IP addresses have a hierarchical design similar to that of telephone numbers For example a 7 digit telephone number starts with a 3 digit prefix that identifies a group of thousands of telephone lines and ends with four digits that identify one specific line in that group Similarly IP addre...

Страница 61: ...xistence A class B network might be appropriate for a large organization such as a business or government agency Class C networks are the smallest only able to hold 254 hosts at most but the total possible number of class C networks exceeds 2 million 2 097 152 to be exact LANs connected to the Internet are usually class C networks Some important notes regarding IP addresses The class can be determ...

Страница 62: ...ans there are two subnets Each subnet uses the remaining 7 bits in field4 for its host IDs which range from 0 to 127 instead of the usual 0 to 255 for a class C address Similarly to split a class C network into four subnets the mask is 255 255 255 192 or 11111111 11111111 11111111 11000000 The two extra bits in Field 4 can have four values 00 01 10 11 so there are four subnets Each subnet uses the ...

Страница 63: ...o the computer you specify If the computer receives the message it sends messages in reply To use it you must know the IP address of the computer with which you are trying to communicate On Windows based computers you can execute a ping command from the Start menu Click the Start button and then click Run In the Open text box type a statement such as the following ping 192 168 1 1 Click OK You can...

Страница 64: ...r DNS server usually located with your ISP If that name is not an entry in your ISPʼs DNS table the request is then referred to another higher level server and so on until the entry is found The server then returns the associated IP address On Windows based computers you can execute the nslookup command from the Start menu Click the Start button then click Run In the Open text box type the followi...

Страница 65: ...s sufficient for your network requirements A 1000 Mbps network 1000BaseTx should use cables labeled Cat 5 10Mbit sec cables may tolerate lower quality cables Network Access PC cannot access another host in the same network 1 Check the Ethernet cabling is good and the LED is green 2 If the port LED is amber check if this port is disabled PCs cannot display web configuration pages 1 The switch is pow...

Страница 66: ...ng default username admin no password Type command sys users show to show username and passowrd you had saved Some pages do not display completely 1 Verify that you are using Internet Explorer v5 5 or later Netscape is not supported Support for Javascript must be enabled in your browser Support for Java may also be required 2 Ping the switch IP address to see if the link is stable If some ping pac...

Страница 67: ... e g the IP address 209 191 4 240 is 11010001 10111111 00000100 11110000 in binary See also bit IP address network mask bit Short for binary digit a bit is a number that can have two values 0 or 1 See also binary bps bits per second CoS Class of Service Defined in 802 1Q the value range is from 0 to 7 broadcast To send data to all computers on a network Ethernet The most commonly installed computer...

Страница 68: ... port and use it to monitor the traffics of other ports on the switch network mask A network mask is a sequence of bits applied to an IP address to select the network ID while ignoring the host ID Bits set to 1 mean select this bit while bits set to 0 mean ignore this bit For example if the network mask 255 255 255 0 is applied to the IP address 100 10 50 1 the network ID is 100 10 50 and the host ...

Страница 69: ... destination IP address and current network conditions A device that performs routing is called a router SNMP Simple Network Management Protocol The TCP IP protocol used for network management STP Spanning Tree Protocol The bridge protocol to avoid packet looping in a complicate network subnet A subnet is a portion of a network The subnet is distinguished from the larger network by a subnet mask w...

Страница 70: ...this field by one When the TTL reaches zero the packet is discarded twisted pair The ordinary copper telephone wiring long used by telephone companies It contains one or more wire pairs twisted together to reduce inductance and noise Each telephone line uses one pair In homes it is most often installed with two pairs For Ethernet LANs a higher grade called Category 3 CAT 3 is used for 10BASE T netw...

Страница 71: ... to the other pages on that web site as well as to pages on other web sites When a user accesses a web site the first page that is displayed is called the home page See also hyperlink web site Web site A computer on the Internet that distributes information to and gets information from remote users through web browsers A web site typically consists of web pages that contain text graphics and hyperl...

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