1

I have HSRP running on two L3 switch and i change priority to higher but it didn't failover, why?

SW1

interface Vlan30
 description Internal_PrivateIP
 ip address 10.5.0.2 255.255.248.0
 no ip redirects
 standby 5 ip 10.5.0.1
 standby 5 priority 150
 standby 5 authentication md5 key-chain foo
end

SW2

interface Vlan30
 description Internal_PrivateIP
 ip address 10.5.0.3 255.255.248.0
 no ip redirects
 standby 5 ip 10.5.0.1
 standby 5 priority 125
 standby 5 authentication md5 key-chain foo
end

I have changed SW1 priority to 150 but still it is showing standby

SW1:

Vl30        5    150   Standby 10.5.0.3        local           10.5.0.1

How do i force failover without network blip?

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2 Answers 2

Reset to default
6

You forgot to use the standby 5 preempt command. It is also a good idea to set a preempt delay.

Hot Standby Router Protocol (HSRP): Frequently Asked Questions:

Q. Which HSRP router requires that I configure preempt?

A. An HSRP-enabled router with preempt configured attempts to assume control as the active router when its Hot Standby priority is higher than the current active router. The standby preempt command is needed in situations when you want an occurring state change of a tracked interface to cause a standby router to take over from the active router. For example, an active router tracks another interface and decrements its priority when that interface goes down. The standby router priority is now higher and it sees the state change in the hello packet priority field. If preempt is not configured, it cannot take over and failover does not occur.

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5
  • You are saying as soon as I will put preempt option it will failover itself?
    – Satish
    Commented Jun 3, 2016 at 1:08
  • Yes. Normally, you want to track an interface or object. When the interface goes down, it can automatically decrease the HSRP priority by whatever value you want. With preempt, the other router can automatically take over when its priority is greater. You can also fail it back with preempt on both. The preempt delay will keep it from bouncing when something is flapping.
    – Ron Maupin ♦
    Commented Jun 3, 2016 at 1:24
  • @Satish, by the way, it will not be without a blip. You will probably lose a few packets, but it shouldn't cause a problem. You can set the timers to less than a second if the milliseconds timers are used, but this can drive up CPU utilization to unacceptable levels, especially on switches.
    – Ron Maupin ♦
    Commented Jun 3, 2016 at 2:00
  • Should i use preempt option on both router? SW1 and SW2 or only SW1 ?
    – Satish
    Commented Jun 3, 2016 at 17:34
  • That depends. Do you want to be able to switch back? You can use it on both.
    – Ron Maupin ♦
    Commented Jun 3, 2016 at 18:46
0

Enable preempt on both sides and write config

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  • Welcome to NE, we hope you will both contribute to and learn from this community. You could improve your answer by editing it to add more details to make it more useful both for the original poster and future users. Typically short answers like this could provide reasoning why you believe this is the answer, more explanation about the concepts mentioned, references/links to supporting resources, or applicable examples.
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    Commented Nov 19, 2019 at 4:54

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