Monday, 28 July 2008

Pesky VRF's

VRF's (Virtual Routing and Forwarding for the uninitiated) are mentioned quite briefly in the CCNP ISCW exam cert guide. So they are a virtual router yada yada seems quite simple. However I had never seen them in an actual CLI. So imagine my surprise when I said oh such and such route does not exist in the routing table and my colleague turns around and says yes it does. So I do show ip route and no route shows up and then I do show ip route and it still does not show up. Well I cannot see it and then my colleague says did you check the VRF. Ohps the VRF so I do show ip route vrf abc and there it is as clear as day the route I have been looking for. Doh mental note to self remember about VRF's however I still occasionally forget but I am getting better.

So I think I have the hang of these pesky VRF things and then I need to telnet to a particular switch. Hmm cannot get onto it hmm what's going on here I wonder. I pluck up the courage to ask colleague another stupid question "erm mate I cannot access core switch 1, is there an ACL on there that is blocking me?". Reply comes back that all should be fine, so what is going on here. Once again it turns out to be the pesky little VRF stuff that has got me stumped. I need to telnet /vrf abc ah that works.

Then a few days later I want to do a show ip bgp hmm output not as expected. Right this time I twig it has to be one of those pesky VRF's getting in my way. So let's try doing show ip vrf abc wooh no bgp command. Okay lets try figure this out show ip ? and look through the options hmm nothing there so how about a show ip bgp ? hmm nothing there either. Argh so I am stumped how the heck do you do a show ip bgp when you have VRF's around? Time to prepare colleague for another stupid question by offering to make him a drink. Once drink has been made then I utilize my chance for another stupid question. "Umm so you know these VRF's how do you do a show ip bgp turns out the answer is to do a show ip bgp vpnv4 vrf abc. So I have enough trouble with VRF's and then they go add the vpnv4 command before the vrf command. Guess I will get to that bit when I sort out multi-protocol BGP. Anyhow you will be pleased to know that I am getting on a lot better with VRF's now. However as with anything on this blog if any of you have any tips, hints or advice please feel free to post it. I have plenty to learn so welcome any teaching :-)

1 comment:

Anonymous said...

ohhh... i having a same problem here! I can't even figure out what's the neighbour router loopback IP via VRF, as it doesn't shows at the diagram... still stucking here... any advice? when I show ip route, it return back to internal router... :(