VRF question

[N W]

Hi Guys

Haven't worked with a VRF setup in years, very rusty.

I've a single route 3900, 3 layer 3 interfaces, each connecting back to an MPLS provider, single BGP instance just different neighbours

On the inside 4 layer 2 ports, with 4 vlan interfaces to route traffic.

whats the best way to set up vrf'd to route out the correct mpls interface?

Thanks

Noel

[Giuseppe Larosa]

Hello Noel,

there is no single answer to this it really depends on what you want to achieve.

With VRFs you create multiple separate topologies. So in your case you can map the 3 WAN links to three different VRFs, then depending on how you map the internal links you associate the traffic of some internal networks to a specific VRF /exit point.

To be noted that without special configurations to exchange routes the VRFs are isolated so if you choice to associate the 3 WAN links to three different VRFs, you actually separate traffic in both directions, but the price to pay is that you haven't  WAN link redundancy anymore.

This is the reason for saying that it depends on what you want to achieve.

IF you are going to map the WAN links to different VRFs you need also to move the eBGP peerings in the appropriate VRF using

router bgp

address-family ipvr vrf

neigh x.x.x.x remote-as 

for each VRF

you define a VRF like

ip vrf YELLOW

rd 100:1

ip vrf RED

rd 100:2

you associate L3 interfaces to a VRF using

interface type x/y

ip vrf forwarding

! you need to reconfigure ip address and mask

ip address y.z.k.t 255.255.255.Z

to be done on each interface you want to associate to a VRF

Hope to help

Giuseppe