"Failover" or "backup" router? 1

[Nijasan]

Hello,

I have a pair of 2621 cisco routers. My goal is this: when one fails, the other one picks up where the toasted unit left off.

I know what the goal is, I just don't know the steps (nor do I know what relevant things to search for on cisco.com) to get to the goal. I also don't know what extra hardware, etc, is required to get from point A to point B.

Does anyone have any tips, sample configs, or things I could search for to help me get this type of setup working?

Thank you in advance.

 

[l1carter]

If you are looking for ethernet redundancy you can configure hsrp on the ethernet links and there are even options to monitor interfaces (you can see if you WAN link goes down).

Sample configuration:

R1.

Interface ethernet0/0
description LAN connection
ip address 1.1.1.2 255.255.255.0
standby 1 priority 110 preempt
standby 1 ip 1.1.1.1

R2.

Interface ethernet0/0
description LAN connection
ip address 1.1.1.3 255.255.255.0
standby 1 priority 115
standby 1 ip 1.1.1.1



WAN redundancy - monitor if you wan link goes down!

standby 1 track serial0/0

to each of the ethernet0/0 configurations.

Authentication

standby 1 authentication ccie

to each of the ethernet0/0 configurations.

SOME GOOD NON CCO LINKS

http://www.cisco.com/pcgi-bin/Support/browse/psp_view.pl?p=Internetworking:HSRP

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094e8c.shtml

 

[Nijasan]

Excellent info. Since my routers are located in a boring colocation facility, there aren't any WAN links to monitor.

I am assuming that I would be OK just using ethernet redundancy, since my routers are "behind" a set of PIX boxes (using the cable failover method) which connects to the colocations ethernet network and so on, so forth.

So here's my config, currently

RouterA -

Interface ethernet0/0
description Cisco 2621xa
ip address 10.0.0.2 255.255.255.0


RouterB -

Interface ethernet0/0
description Cisco 2621
ip address 10.0.0.3 255.255.255.0

The config that I'm proposing:

RouterA -

Interface ethernet0/0
description Cisco 2621xa
ip address 10.0.0.2 255.255.255.0
standby 1 priority 115 preempt
standby 1 ip 10.0.0.4

RouterB -

Interface ethernet0/0
description Cisco 2621
ip address 10.0.0.3 255.255.255.0
standby 1 priority 110 preempt
standby 1 ip 10.0.0.4



Is that really all there is to it? Seems too good to be true. Then (since I was using this as the 10.0.0.0 gateway) I'll just need to change my machines to have a gateway of 10.0.0.4, and I'll be set. Right? Wrong?

 

[rburke]

I would also use the command "standby mac-address xxxx.xxxx.xxxx" on each of the interfaces. That way if one does go down then you won't have to worry about any ARP delay while the end users find out the "new" Mac of the default gateway.

Burke

 

[l1carter]

That's it!

I would suggest looking into the track interface for standby configurations. If your farend (connection to the pix's) goes down it's possible to route packets to your active router then pass them back to the standby for further routing! Not a good performance Idea. I would need to know more about the backend configurations to make an accurate conclusion.

As for your proposed configs you are 100% on the money!