HSRP Test w/ loopback?

[froggerdata7]

Can you test HSRP using a loopback interface?  Is that possible?  I'm trying to test our HSRP setup before we connect it to prod, so I have the IP's that it will use setup.  But wanted to see the HSRP in action before deploying.

[Jon Marshall]

Can you provide a few more details ie. what devices do you want to test it on and why you need to use loopbacks ?

Jon

[Richard Burts]

Like Jon I am not sure what you are really trying to achieve and some clarification would be helpful. It sounds like you want to test HSRP by configuring it on loopback before you config it on Ethernet. This will not work. HSRP requires that the peers be connected on a common subnet. A loopback by its nature is not connected to anything. 

HTH

rick

[froggerdata7]

I can certainly provide more details.  My bad, I should have provided more details.

I have a pair of 3845s configured with HSRP.  I wanted to test them and make sure the configuration is correct.

3845 #1 Configuration

Interface gigabitethernet 0/0.200

ip address x.x.x.210 255.255.255.248

standby 1 ip x.x.x.209

standby 1 priority 150

standby 1 preempt

3845 #2 Configuration

Interface gigabitethernet 0/0.200

ip address x.x.x.211 255.255.255.248

standby 1 ip x.x.x.209

standby 1 priority 101

standby 1 preempt

I guess I could simply unplug the cable and watch the debug and see what happens.  A colleague said I could use loopbacks, so I'm just trying to figure how to do that.  How do you guys test your HSRP before dropping it into prod?

[Jon Marshall]

To test it -

1) "sh standby brief" on both routers to make sure it is working when they are both up and running and connected ie. one should be active and the other standy.

2) shut the interface or pull the cable on the active router and you should see the standby become active.

3) unshut or reconnect and you should see the old active router become active again.

As Rick pointed out using loopbacks won't work because you need  the interfaces to be in the same vlan/IP subnet and with loopbacks you don't get that.

Jon

[froggerdata7]

Thanks guys, I appreciate the responses!!  I know it sounds like a simple stupid question, but this is my first time implementing HSRP in production.  I've done it in the lab, but in prod it's a whole different story as you throw in 'worry' now.

Cheers!

[Bilal Nawaz]

Hi Evan, you can test by simply shutting one of the sub interfaces down at a time, with a ping running (from anywhere with reachability) to the HSRP address. With this testing going on, you are able to do your relevant show commands to check if your config is working the way you want it to. Once done with testing, bring interfaces back to an UP state and its ready to go.

hth.

[Richard Burts]

The partial config that you posted looks reasonable and the HSRP configured should work (assuming that there is appropriate layer 2 and layer 3 connectivity between these routers). As far as testing HSRP configuration, unless you have a test environment that exactly mimics your production environment (same platforms, same versions of IOS, same physical connectivity) there is really not a way to test HSRP.

If you have a colleague who suggested that you could test this with loopbacks, either that colleague did not correctly understand what you were trying to test or else you should seriously dial back the trust factor on any advice that they give you.

HTH

Rick