Cisco 3825 - Manual (Page 89)

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Cisco 3825 Mobile Wireless Edge Router Software Configuration Guide
OL-15667-03
Chapter 4 Configuring the Cisco 3825 Mobile Wireless Edge Router in a RAN-O Solution with the Command-Line
Configuration Sequence
• hellotime—Hello interval (in seconds). This is an integer from 1 to 254. The default is 3 seconds. If
the msec option is specified, hello interval is in milliseconds. This is an integer from 15 to 999.
• holdtime—Time (in seconds) before the active or standby router is declared to be down. This is an
integer from x to 255. The default is 10 seconds. If the msec option is specified, holdtime is in
milliseconds. This is an integer from y to 3000.
Where:
– x is the hellotime + 50 milliseconds, then rounded up to the nearest 1 second
– y is greater than or equal to 3 times the hellotime and is not less than 50 milliseconds.
For example, the following command specifies the hot standby group 1 with the timers set between 1
and 3 seconds:
Router(config-if)# standby 1 timers 1 3
Step 14 To configure HSRP preemption and preemption delay, use the standby preempt command in interface
configuration mode. To restore the default values, use the no form of this command.
Note Without preemption, a standby router will transition to the active state only if HSPR “hello
packets” cease. In a RAN-O solution, you may sometimes want a switchover to occur in the
absence of a router GE failure; therefore, you need to configure preemption.
Router(config-if)# standby [group-number] preempt [delay{minimum delay|reload delay|sync
delay}]
Where:
• group-number—(Optional) Group number on the interface to which the other arguments in this
command apply.
• delay—(Optional) Required if either the minimum, reload, or sync keywords are specified.
• minimum delay—(Optional) Specifies the minimum delay period in delay seconds. The delay
argument causes the local router to postpone taking over the active role for delay (minimum)
seconds since that router was last restarted. The range is from 0 to 3600 seconds (1 hour). The
default is 0 seconds (no delay).
• reload delay—(Optional) Specifies the preemption delay period after a reload only. This delay
period applies only to the first interface-up event after the router has reloaded.
• sync delay—(Optional) Specifies the maximum synchronization period for IP redundancy clients in
delay seconds.
For example, the following command specifies the hot standby group 1 with preempt:
Router(config-if)# standby 1 preempt
Note The default group number is 0. The default delay is 0 seconds; if the router wants to preempt, it will do
so immediately. By default, the router that comes up later becomes the standby.