vrf-lite + HSRP

Unanswered Question
Feb 19th, 2007


I am rather new to VRF-lite so I need to ask the following:

I need to configure vrf-lite on 2 of the core switches in one building so I can have separate routing tables. Together with that I need to implement redundancy in the network so if one of the core switches dies, the users continue working. Can I implement vrf-lite on the 2 core switches with the same vrfs on them, without using mpls, and use hsrp for every vlan in my network? I have posted a diagram to explain my situation better. My users are conneced through a L2 switch to 2 core switches. The idea is to configure default gtwy for the users to be hsrp intf on the core switches (for every vlan). Vlans are grouped in vrfs in the same manner on both core swotches. Do I need anything else in order for this to work (mpls etc..) or is this enough? There will be no load balancing, only one of the core switch will be doing the work and the second one will be stand by.

I have this problem too.
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Yongbing WU Mon, 02/19/2007 - 12:33

You do not need MPLS to make vrf-lite to work. Your diagram looks good.

Hope this helps.

zlabovic Mon, 02/19/2007 - 22:37

I am a bit puzzled about having two core switches with the same vrfs on them and no protocol between them so they are aware of having the same vrfs.

mheusinger Tue, 02/20/2007 - 00:38


in fact the core switches do NOT know, they have the same VRFs configured in vrf-lite.

Think of VRF-lite as a method to implement separate routers in software (somewhat simplified). All you do is interconnecting those "VRF routers", where connectivity is required and NOT to interconnect, where no connectivity is required.

Another example with 4 routers physically separated:

R1 - R2 and separately R3 - R4

Does R1 know anything about R3 and R4? Obviously no. How does R1 know it "belongs" to R2? Well, they are physically interconnected and CAN learn each other, if apropriate protocols are enabled (f.e. OSPF).

Now think of R1 to R4 being different "VRF routers". The same statements as in the physical network apply.

Hope this helps!

Regards, Martin

jasonmcl Tue, 02/20/2007 - 08:14

network masters!! :) I have a very similar problem that is eluding me. please look at the drawing attached and see if it is similar to the posters issue. Seems similar. my issue is that i need vrf with nat, can vrf lite do nat? maybe together with my problem and his someone out there will know how to help me.


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