HSRP Tracking question

[Armegeden]

Hello all,

This is an idea of what I have configured:

Vlan1

ip address 10.10.100.2 255.255.255.0

standby 100 ip 10.10.100.1

standby 100 preempt

standby 100 priority 110

standby track Gi1/1 10

Vlan2

ip address 10.10.200.2 255.255.255.0

standby 200 ip 10.10.200.1

standby 200 preempt

standby 200 priority 110

standby track Gi1/1 10

Now, I have this setup on a 4503 that is directly connected to two other 4503's with similiar setups (different vlan IP's of course). A triangle topology I guess...

There are about 20 Vlan's defined this way...

Do I need the "track" command on each HSRP instance? If that link goes down, will it reduce the priority by -10 for each Vlan that is tracking? Taking away 10 from 110 many, many times?

(the other 4503's have different priorities... one is 105, other is 103)

[amit-singh · Accepted solution]

Hi Armegeden ,

Yes, you have to track Gig interface on each and every Vlan. That what you actually want, if you track only Gig interface only for one vlan, your rest of the vlans still will be active for HSRP on the switch whose gig link has failed and will result actually in service disruption.

It will reduce its priority by the vlaue assign to the interface.

regards,

-amit singh

[Armegeden]

Thank you, Amit, that is exactly what I was asking about.

Now that I'm thinking of it though, is the "track" command necessary? If the Active HSRP goes completely down, will the Backup HSRP (priority 105) take over?

What if just Gi1/1 goes down on the Active HSRP but the switch itself stays up, will the Active HSRP remain active if I take out the "track" command?

I guess what I'm asking is:

The "track" command is used to monitor a critical interface, correct? If the track command is NOT used, then the only way the Backup HSRP would take over is if the Active HSRP were to completely disappear or power off?

[amit-singh]

Hi,

Yes, you are absolutely right about it. It is used to track the critical interface.Imaging that you have 2 routers A and B at you location, A being the primary and B scondry for your HQ link. If you dont track the interface and if the link goes down, the client at you end will still try to forward the packet to its gateway which is A but the link is down. There is not way for B to know that the link has gone down and it should take over as active router. This is where your " interface tracking " feature comes inot the picture. Now to shift the traffic to secondry B router, you have to power-it off.

HTH,

-amit singh