virtual routing table in router

[suthomas1]

Hello,

The network consist of 3 vlans which sits on the core 3750 switch. there is a PE router to which this 3750 should be connected and communicating.

Following needs to be achieved:-

1. all three vlans need to be under one single vrf . How do we configure this on the 3750 portion

2. there needs to be bgp peering between the PE and 3750 for route exchange, how should this configuration be done

Thanks in advance!

[Giuseppe Larosa]

Hello Suthomas1,

1)  all three SVI L3 interfaces can be associated to the default Global Routing table or to a vrf (if desired)

in first case nothing special has to be done ( default).

For associating the SVI to a VRF

a) configure the VRF

ip vrf  RED

rd 100:100

route-target both 100:100

!

B)

under each interface SVI

interface Vlan X

ip vrf forwarding RED

! retype ip address and mask !!!

ip address a.b.c.d  255.255.e.f

2)

a BGP session should be defined under VRF RED if links have been associated to it

router bgp

address-family ipv4 vrf RED

neigh 10.1.1.1 remote-as SP-AS

All this under the hyphotesis that :

- IOS version supports VRF and BGP

- SDM template is appropriate on the C3750 ( this tells how to use the TCAM resources)

Hope to help

Giuseppe

[suthomas1]

Thanks Giuseppe.

But due to my lack of depth on knowledge for this subject, i would request to elaborate slightly on this , under the following conditions:-

1. 3 vlans - A(192.168.100.1) , B(192.168.150.1) , C(192.168.181.1)

all these three need to be in one VRF RED

2. do i need a seperate bgp configuration to get the peering up between this switch and the PE device.

   ( let us assume, we'r using int ge0/2 to physically connect the link to the PE device )

what configuration will be needed here.

[Giuseppe Larosa]

Hello Suthomas1,

also the interface to PE node gi0/2 has to be associated to the same vrf RED using the same commands as for the SVI ( remember to retype the IP address because association to a VRF removes the IP address from an interface)

the configuration of the eBGP session is performed as I have explained in my first post under

router bgp

address-family ipv4 vrf RED

network A.b.c.d mask 255.255.255.0

neigh x.x.x.x remote-as SP-AS

You need a network command for each internal Vlan or a redistribute connected

you can check the state of the BGP session in VRF using

show ip bgp summary vpnv4 all

also IP connectivity check has to be performed with

ping x.x.x.x vrf red

show ip route vrf RED

shows the IP routing table for the routing table

see the VRF lite chapter for complete examples

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/31sga/configuration/guide/vrf.html

Hope to help

Giuseppe