HSRP

[gowdakssujan]

What is difference between hold timer, active timer and standby timer? They're all purposes same

[Seb Rupik]

Hi there,

This document explains their purpose:

https://www.cisco.com/c/en/us/support/docs/ip/hot-standby-router-protocol-hsrp/10583-62.html#topic14

cheers,

Seb.

[paul driver]

Hello

standby xx timers x( hello 5)  x (hold timer)

Hello timer - is the time value that the router will send a hello to its neighbor to see if its active
Hold timer  -  is the time value the rtr will wait if no response to that hello is received

Active/Standby rtr timer is based on both the hello and hold timers, meaning if the rtr it doesn't receive a hello its active/standby timer will be the hold time value however it should not get down to that as it should refresh every received hello.

example:

standby x timers 5 15

Active-Standby/Hold timer = 15 seconds
Hello is 5 seconds = So every 5 seconds a hello will be send so the active/standby timer should not go below 10 seconds until its refreshed however if it doesn't receive a response from a hello it will count down from 15 seconds to 0 before stating the active peers is not reachable.

[gowdakssujan]

Does the uptime of the router matters while electing the active router?

[paul driver · Accepted solution]

Hello

If preempt is enabled then no it shouldn't has if/when a peer comes up which has a preferred higher priority then it will take the active role irrelevant of how long the initial active peer has been up

[gowdakssujan]

How many standby routers an HSRP standby group can have? 

[paul driver]

Hello

Hum not so sure  tbh the priority value ranges from 0 255 so it could be quite extensive however the probability of multiple rtrs failing in you hrsp environment at the same time is I would say very low so you wouldn’t require that many I guess.