What is the packet flow from one host to another between 2 VRFs?

[Rinam Shah]

Please help to understand on how packet travel from one vrf to another in MPLS VPN.

@Giuseppe Larosa 

[MHM Cisco World]

Can you more elaborate?

[Rinam Shah]

Please help to understand on how packet travel from one vrf to another in MPLS VPN network.

[MHM Cisco World]

Ce1-pe1-mpls-pe2-ce2

Pe1 have vrf red 

Here be notice vrf not carrying with packet ip header, it locally know for only pe1

So what pe1 do?

Pe1 config rt under each vrf 

Pe1 running mp-bgp this protocol advertise route(route with it rd) + rt

Mpls forward this mp-bgp to pe2 

Pe2 have vrf blue 

Pe2 under vrf import any route that have rt same as you config.

Pe2 now get route even if it run different vrf than pe1. 

[Rinam Shah]

Thank you for the answer.

If CE1 has vrf configured with only rd configured, how would the packet flow to another vrf at PE1? Could you please share detailed packet flow?

[MHM Cisco World]

What is ce-pe protocol 

Is it 

Static
OSPF
BGP ? 

[Giuseppe Larosa]

Hello @Rinam Shah ,

>> If CE1 has vrf configured with only rd configured, how would the packet flow to another vrf at PE1? Could you please share detailed packet flow?

in that case CE1 can act as a multi VRF CE a.k.a known as VRF lite.

A VRF lite device has a subset of features of a SP provider PE node.

More specifically the forwarding plane does not use MPLS labelled path.

This means that a multi VRF CE serving M VRF requires M+1 logical links i.e. VLAN subinterfaces, or ATM or Frame Relay subinterfaces.

The +1 is used for MP BGP signaling (if used ).

The use of route targets allow for route exchanges between VRFs locally defined or leaened playing with route targets.

Please note that:

import here means prefxes coming from another VRF and it is configured on the VRF rx side. both drections need to be configured.

export means .prefixes with RT value(s) that makes them imported on the other rx VRF.

Hope to help

Giuseppe

[MHM Cisco World]

for BGP 
PE1 VRF RED
CE1 VRF BLUE  

under PE1 bgp 
address-family ipv4 vrf RED
neighbor CE1 remote AS-CE1

under CE1 bgp 
address-family ipv4 vrf BLUE 
neighbor PE1 remote AS-PE1 

the link between PE1-CE1 must config with ip vrf forwarding 
PE1 
ip vrf forwarding RED
CE1
ip vrf forwarding BLUE 

now in CE1 
show ip route not show anything 
show ip route vrf BLUE 
you will find route