PE-CE connectivity

Unanswered Question
Oct 14th, 2007


CE router is two hops away. R1 & R2 are ISP non-mpls ISP routers. IGP of ISP can be considered as OSPF/IS-IS. What are the connectivity options between PE and CE?

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Bharat Negi Mon, 10/15/2007 - 23:52

Hi Swaroop

Thanks for your suggestion but it doesn't seems to be scalable. In future customer base increases, there would be lot of GRE/L2TP tunnels on PE router.

Also, is it possible upgrade R1 & R2 PE as MPLS rouers and connect them to PE.

PE <---R1(PE)---R2(PE)--->CE

I am not sure of this. Can we connection PE to PE. If yes then how?



swaroop.potdar Tue, 10/16/2007 - 02:18

Bharat, infact if the ISP routers are in your control, and dont belong to other SP, then its much easier to implement IPv4 and MPLS based switching concurrently.

You can integrate the intermediate IPv4 routers into MPLS by extending the IGP across and enabling LDP. (also you need to integrate these devices with your VPNv4 RR and IPv4 RR as well) This should take care of your IPv4 traffic as well as have MPLS extended across those devices.

But one thing I am not sure is if these are ISP routers then why only 2 routers are there, are they a part of a bigger network or they are just 2 standalone routers in between your PE and CE.



Bharat Negi Tue, 10/16/2007 - 02:43

Hi Swaroop

These routers are ISP routers and are managed thru IGP (OSPF). More or less acting as CE for MPLS backbone but under ISP control. The number is not just limited to 2, it can vary.

Customer sites are very remote from MPLS POP. Hence there routers are being used to extend the MPLS rechability.

As per your suggestion, I need to run LDP on these routers and enable peering with VPNv4 and IPv4 RRs.

Just a query: Can I run BGP between PE and CE (over R1 & R2). This way I don't need to extend my MPLS.


swaroop.potdar Tue, 10/16/2007 - 08:24

Although you may be able to have ebgp formed but only problem with that is, since its a CE it would have private IP's, how would they be routed in through the ISP cloud.



Bharat Negi Tue, 10/16/2007 - 20:17

To address that, I will assign a /32 public IP to customer and can use it for BGP peering and CE management. I think, there would not be a problem by advertising that /32 IP in my IGP.

Please suggest any other work around.



This Discussion