Want to verify self understanding of RD/RT in L2/L3 MPLS VPN context

Hello experts,

I am a new member of INE
and read about couple of courses on RD/RT BGP router configuration.

My query is on following
simple topology 

CE1-->
PE1<--------> PE2 -->CE2

My understanding is that
RD is used to distinguish different VPNs/Customers on a PE so that same IP
address could be used in 2 different VPNs/customer sites on same PE. Now the RT
is used to uniquely identify the right VRF for that VPN/customer to forward
packet on other side. If an iBGP update travel from PE1 toPE2 , the first thing
PE2 does is to stripped of the RD and based on RT information any labeled MPLS
packets will be put into right VRF to deliver to CE2. 

In the above scenario the
RT needed to be unique across all PEs. Is my understanding correct?

With regards,

 

Samarjit

Comments

  • Hi,

    RT is used to control import/export routes on PE routers, if you export RT 100:100 on VRF_A, the remote PE should import same RT value to get VRF_A routes installed in the routing table.

    HTH

  • Hi,

    Thanks for replying. Thus if a PE has 2000 VRFs, we require 2000 unique RT values both on local PE and remote PE to identify the same route instances. ?

    With regards,

    Samarjit

  • Import/Export RTs can be similar in some instances but if you were to seperate your customers with VRFs, you would need different RT values per VRF. 

  • Ok, thats great. 

    Now there is another scenario. 

    Lets assume Customer-A wants 2 different VPLS instances for its' HR and Enginerring departments. Is it require to create 2 different VRF for same customer? 

    With regards,

    Samarjit

  • Hi, 

    If you are referring to Cisco's VPLS implementation, you would need to have two seperate VPLS bridge domains to fulfill your requirement. 

    If you are referring to the L3VPN scenario, it would need to have two VRFs to segregate two different services. 

    HTH

  • Thanks a lot. 

    Could you please provide configuration steps for

    1. Two VPLS bridge domains for L2 VPN and 

    2. Two VRF configuration for L3VPN? 

    Any good reference for doing the above configuration also works for me. 

    With regards,

    Samarjit

Sign In or Register to comment.