HSRP tracking via IP

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Jul 31st, 2007
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There's a way of tracking a remote IP via icmp with HSRP. If this IP is not reachable then it will force the failover. I believe the the way it works is once the remote IP is unreachable the timer starts, the service provider is stating that the timer is when the IP address is checked. which is it please?

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mohammedmahmoud Tue, 07/31/2007 - 06:42
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Hi,


You can track the reachability of the IP in the routing table.


track 100 ip route reachability

!

interface Ethernet0/0

ip address x.x.x.x

standby 1 preempt

standby 1 ip y.y.y.y

standby 1 priority 110

standby 1 track 100 decrement 20


HTH,

Mohammed Mahmoud.

Edison Ortiz Tue, 07/31/2007 - 06:48
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Yes, you can track a remote IP with HSRP and it doesn't have to be via ICMP. You can use the track feature within IOS.


Let's say you have this route in your RIB (192.168.1.0/24)


Then you configure the track with:


track 1 ip route 192.168.1.0/24 reachability


And your HSRP with:


interface [module/port]

ip address 172.16.1.1 255.255.255.0

standby ip 172.16.1.254

standby preempt

standby priority 105

standby track 1 decrement 10


As soon as the route is no longer in the routing table, the HSRP priority will be 95 and the other HSRP router will take over.


jtrumbell Thu, 08/02/2007 - 10:12
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Isn't there a way where a IP is selected and is checked via icmp. Once it becomes unreachable then a timer begins and the failover occurs. I thought I saw it as a HSRP tracking option, it could have been a VRRP tracking option? thanks

Edison Ortiz Thu, 08/02/2007 - 10:20
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You can use IP SLA for ICMP checks, however this may create unnecessary traffic in your network. It's best to track interfaces/routes based on their current state.

jtrumbell Thu, 08/02/2007 - 10:38
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Yes, but in this situation we want router A to failover immediatly when anything occurs with or beyond Router B. We dont want to wait for the routing update, if the client base notices a pause or a timeout they call into the helpdesk. So whenever possible we want any failovers to be invisible to the client base. Waiting for the routers to converge will likely cause some session timeouts.



Edison Ortiz Thu, 08/02/2007 - 10:41
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When the connection is lost the routing update will be triggered and it will react as quick or even faster than a ping response.


Please try in a Lab before implementing and you will see what I'm referring.

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