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New Member

Issue Exporting routes from one VRF into another and Vice Versa

I am designing/building a new MPLS architecture to support a very large application and have run into a very interesting problem and I am stumped.

I have multiple VRFs that need to talk to each other between their Server/LAN Segments. Most of these segments are Directly connected on the Same PE router. I can extranet between them and everything on the Surface looks OK. However when I try and communicate between the VRFs nothing happens. The Routing table looks ok as well CEF and BGP. Nothing in the Forwarding Table though. Anyway I cannot communicate to the other Servers located in the other VRFs but the servers can obviously talk to each other on the local Segment. I can communicate to the other VRF interfaces between the PEs, just not beyond them. Any thoughts?

7 REPLIES
Cisco Employee

Re: Issue Exporting routes from one VRF into another and Vice Ve

When you say "Nothing in the forwarding table", do you mean in the LFIB or the FIB. It is normal not to see anything in the LFIB as traffic between the two VRFs will not be MPLS switched.

Do you have a default route configured on all of your servers?

Could you also clarify the following statement:

"I can communicate to the other VRF interfaces between the PEs, just not beyond them."

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Issue Exporting routes from one VRF into another and Vice Ve

The Server Default route is set to the PE that has routes to the other VRFs.

I can reach addresses in the other VRFs that are devices such as a router or Switch but not Servers...ODD. These other Routers have no other routing setup than an interface on the same VLAN as the PE. I can also reach interfaces on other PEs that are on the different VRFs as I should...Just not Servers beyond that even though I have the routes in the routing table.

New Member

Re: Issue Exporting routes from one VRF into another and Vice Ve

If Traffic between 2 VRFs is not switched via MPLS how is it supposed to be routed? I see the routes in the places you might expect them but I am at a complete loss as to why I cannot have 2 Servers with the default gateways set to the PE devices talk to each other through the PE.

Cisco Employee

Re: Issue Exporting routes from one VRF into another and Vice Ve

If treaffic is just between two interfaces in different VRFs, MPLS is not involved whatsoever. You should have an entry in each VRF pointing at the other the subnet in the other VRF. Could you please provide a couple a commands showing that these inter VRF routing entries exist.

Thanks,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Issue Exporting routes from one VRF into another and Vice Ve

Problem solved...I am gonna have the Server people Flogged.It was a server issue after they swore up and down to me that they had everything was setup correctly.

thx.

New Member

Re: Issue Exporting routes from one VRF into another and Vice Ve

Here is the Scenario:

VRF D1 Overlapping rfc1918 address space

VRF D2 Overlapping rfc1918 address space

VRF D1A Server Rail

VRF D2A Server Rail

VRF D1 imports all its routes into D1a and VRF D2 imports all its routes into D2A. This works great.

VRF D1A exports its Server Segment Routes to D2A using Extended Communities and ViceVersa. These VRFs reside on the Same PE just separated be different VLAN Interfaces. The Routes to each VRF/VLAN show up as connected routes. Next-hop being the VLAN appropriate VLAN interface. I can reach the interfaces on the PE between VRFs but I cannot get Servers that are on the 2 different VRFs to communicate. Their Default gateway is setup to be the PE interface

Re: Issue Exporting routes from one VRF into another and Vice Ve

Hi Matt,

what is the output from a traceroute from one server to the other server? Where does it stop?

Just to make sure not to run into some "Windows firewall unintentionally activated" issues: can you trace/ping each server from the attached PE? What does a ping/trace from the PE interface in one VRF to the server in the other VRF result in?

Regards

Martin

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