Redistribution

[l2828]

Hello, I'm confused about something and would appreciate any guidance or assistance.

In my topology, each PE router is located in a different AS and is directly connected to the CE router. Each AS is running iBGP alongside an IGP. VRFs and MP-BGP have been configured on all PE routers. From my understanding since I have redistributed the BGP routes into the VRFs, there should be connectivity between CE routers from different sites, however this is not the case.

Should BGP routes be redistributed into the IGP or should IGP routes be redistributed into BGP? How to create connectivity between different sites without creating potential routing loops?

Thanks!

[MHM Cisco World]

In PE bgp must redistrubte into igp vrf aware

In PE igp vrf aware must redistrubte under bgp ipv4 vrf address family

To make CE in different site connect to each other you need to make sure PE use correct RT values (import and export)

MHM

[Joseph W. Doherty]

Could you verify your topology because, for example, how are the PEs interconnected, and what do your VRFs represent.

Traditionally/typically, for different customers, PEs would be in the same AS, eBGP peering with the CEs.  The CEs, perhaps, doing selective distribution with an IGP.  Often, no need for CE VRFs.  PE VRFs would likely used for different customers.

[l2828]

Sorry for the miscommunication, to clarify: I'm trying to create a MPLS L3VPN and in my topology design each AS has one or more PE routers. Each PE router is directly connected to a CE router via a serial link. I have configured VRFs on all PE routers and applied it to the interface facing the CE router. I am running eigrp on the link between PE and CE routers for connectivity.

My Question is since the PE routers are using VRFs and MP-BGP, how can I allow the CE routers to communicate with each other? Hope that makes sense, thanks!

[Joseph W. Doherty]

My Question is since the PE routers are using VRFs and MP-BGP, how can I allow the CE routers to communicate with each other?

How new are you to this subject?

I ask, because your question revolves around using RDs and RTs, and MP-BGP.

For example, do you understand an article like: https://ipwithease.com/rd-vs-rt-in-mpls/

[M02@rt37]

Hello @l2828 

Should BGP routes be redistributed into the IGP or should IGP routes be redistributed into BGP? 

->Redistributing BGP into the IGP is highly discouraged in service provider/MPLS...routing loops, excessive IGP state...

As concerned IGP to BGP redis, if the CE learns routes via IGP (OSPF, EIGRP), then redistribute IGP into the PE’s VRF BGP (per VRF). You could also use BGP on the CE-PE link, which is preferred in inter-AS VPN scenarios (especially when AS differ), to avoid redistribution altogether.

[paul driver · Accepted solution]

Hello

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@l2828 wrote:

Sorry for the miscommunication, to clarify: I'm trying to create a MPLS L3VPN and in my topology design each AS has one or more PE routers. Each PE router is directly connected to a CE router via a serial link. I have configured VRFs on all PE routers and applied it to the interface facing the CE router. I am running eigrp on the link between PE and CE routers for connectivity.

My Question is since the PE routers are using VRFs and MP-BGP, how can I allow the CE routers to communicate with each other? Hope that makes sense, thanks!

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Each PE rtr will have
 -IGP process (possibly OSPF /ISIS) for backbone mpls transit
- Eigrp vrf process with the CE rtr so it can inherit the CE rtr routes
- L3VPN  between each PE rtrs
- Mutual redistribution would be required on the PE rtrs between the EIGRP/iBGP processes with the vrf route targets allowing the export/import of each CE rtrs prefixes so provide reachability between sites

See attached for a basic example:

[paul driver · Accepted solution]

My Question is since the PE routers are using VRFs and MP-BGP, how can I allow the CE routers to communicate with each other? Hope that makes sense, thanks!