HSRP (Hot Standby Routing Protocol)

Hello Rene,
thanks for your interesting lesson, as always, I like your way to explain and clarify things. :slight_smile:

I wonder, if I can reach my following goal with HSRP. I have a HSRP group running. Both routers have each a running upstream and downstream OSPF connection to 2 different routers . What I need to reach is that only the active router takes part in OSPF, the standby must not participate in OSPF at all, as long as it’s becoming active. I don’t want the standby router to show up in the neighbor table of the other OSPF speakers. Adapting OSPF costs does not get me any further…
Thanks for your time!

Hello Christina

Remember that HSRP is primarily used as a method for achieving gateway redundancy for end devices such as PCs, IP phones, IP cameras, printers etc… This means that the redundancy group that is created on a pair of Layer 3 devices using HSRP should be facing a subnet with such end-user devices.

Now based on your description, you are trying to use HSRP to provide gateway redundancy to OSPF routers, correct? Now, this can be done, however, it is not the most elegant solution. This is because typically, the virtual IP created via HSRP cannot participate in OSPF (or any routing protocol for that matter). Only the “real” addresses can participate. This presents a problem when attempting to achieve redundancy.

In general, if you want to achieve such redundancy, you should use the load balancing and rerouting capabilities of the routing protocol itself rather than relying on HSRP. However, can you let us know a little bit more about what you want to achieve, and why you want only the active router to participate in OSPF and not the standby router? Maybe we can suggest another solution for your requirements.

I hope this has been helpful!

Laz

Hello Laz

Thanks a lot for your reply.
My generell goal to achieve is to create a copy of our production environment in GNS3. I want to represent a firewall cluster here. As the real firewall cluster would gobble up huge amounts of resources within GNS3, my idee was to replace it with 2 HSRP routers as the firewall rule set would not be needed in GNS3. The firewall cluster provides local redundancy as well as represents itself as a single OSPF speaker to others, meaning if the firewall master goes down, the slave takes over (just like HSRP) and only the slave (new master) talks OSPF withe the SAME ROUTER ID that the former master used… Always only one OSPF Router (firewall) can be seen from the perspective of the other speakers…
But as I learned now, this will hardly to be achieved by using a HSRP pair…

Hello Christina

Ah, I understand. Yes, HSRP is not a good choice to “simulate” the redundancy provided by a firewall cluster, and you can’t achieve what you need in this way. How large is the firewall cluster you want to create? It may be worth taking a look at the GNS3 forum to see how others have achieved such simulations…

I hope this has been helpful!

Laz

Hi team, quick question.

Is it correct to configure preempt delay minimum 60 on both switches?

SW1 & SW2
(config)#interface Vlan 1
(config-if)#standby 1 preempt delay minimum 60

I thought it should only be configured on the master HSRP so if it reloads (for whatever reason) it doesnt assume the master/active role immediately so to allow in your words “OSPF or EIGRP need to form neighbor adjacencies or spanning-tree isn’t ready yet unblocking ports,” if need be.

Thanks in advance.

I’d appreciate your support here.

Hello NetworkGuy

You can issue this command on both devices if you wish, however, it will only really have meaning if you configure it on the device that has the higher priority. What preempt does is this:

If both devices are up, and the device with the higher priority is not active, it preemptively becomes active.

There will never be a case where both devices are up, and the device with the lower priority will preemptively take control. So you may configure it on the device with a lower priority, but for that device, the preemptive conditions will never occur. Since preemption will never take place, the delay parameter is also moot.

I hope this has been helpful!

Laz

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