Foundry Networks Switch and Router, Руководство по установке и настройке

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Configuring BGP4
December 2000 19 - 27
Optional Configuration Tasks
The following sections describe how to perform optional BGP4 configuration tasks.
Changing the Keep Alive Time and Hold Time
The Keep Alive Time specifies how frequently the router will send KEEPALIVE messages to its BGP4 neighbors.
The Hold Time specifies how long the router will wait for a KEEPALIVE or UPDATE message from a neighbor
before concluding that the neighbor is dead. When the router concludes that a BGP4 neighbor is dead, the router
ends the BGP4 session and closes the TCP connection to the neighbor.
The default Keep Alive time is 60 seconds. The default Hold Time is 180 seconds. To change the timers, use
either of the following methods.
NOTE: Generally, you should set the Hold Time to three times the value of the Keep Alive Time.
NOTE: You can override the global Keep Alive Time and Hold Time on individual neighbors. See “Adding BGP4
Neighbors” on page 19-14.
USING THE CLI
To change the Keep Alive Time to 30 and Hold Time to 90, enter the following command:
BigIron(config-bgp-router)# timers keep-alive 30 hold-time 90
Syntax: timers keep-alive <num> hold-time <num>
For each keyword, <num> indicates the number of seconds. The Keep Alive Time can be 0 – 65535. The Hold
Time can be 0 or 3 – 65535 (1 and 2 are not allowed). If you set the Hold Time to 0, the router waits indefinitely for
messages from a neighbor without concluding that the neighbor is dead.
USING THE WEB MANAGEMENT INTERFACE
1. Log on to the device using a valid user name and password for read-write access. The System configuration
panel is displayed.
2. Click on the plus sign next to Configure in the tree view to expand the list of configuration options.
3. Click on the plus sign next to BGP in the tree view to expand the list of BGP option links.
4. Click on the General link to display the BGP configuration panel, shown in Figure 19.2 on page 19-8.
5. Edit the number in the Keep Alive Time field. The Keep Alive Time can be 0 – 65535.
6. Edit the number in the Hold Time field. The Hold Time can be 0 or 3 – 65535 (1 and 2 are not allowed). If you
set the Hold Time to 0, the router waits indefinitely for messages from a neighbor without concluding that the
neighbor is dead.
NOTE: Generally, you should set the Hold Time to three times the value of the Keep Alive Time.
7. Click the Apply button to apply the changes to the device’s running-config file.
8. Select the Save link at the bottom of the dialog. Select Yes when prompted to save the configuration change
to the startup-config file on the device’s flash memory.
Enabling Fast External Fallover
BGP4 routers rely on KEEPALIVE and UPDATE messages from neighbors to signify that the neighbors are alive.
For BGP4 neighbors that are two or more hops away, such messages are the only indication that the BGP4
protocol has concerning the alive state of the neighbors. As a result, if a neighbor dies, the router will wait until the
Hold Time expires before concluding that the neighbor is dead and closing its BGP4 session and TCP connection
with the neighbor.