Unified MPLS
Lab file
Startup configs
IP addressing, IGP, and LDP have been pre-configured.
The objective is fairly straight forward but will be challenging to implement. You must achieve an end-to-end LSP between Access-R1 and Access-XR5 without redistributing loopbacks into the separate IGP “islands.”
To do this you must setup Unified MPLS. Use BGP ASN 100. Create an E-Line service, enabling CE1 to peer with CE2.
Once this is complete CE1 should learn CE2’s loopback via OSPF:
Access-R1 should only have Core-R2’s loopback known via the IGP.
For the E-Line service, Access-R1 will need to match traffic tagged with 100 from CE1. Access-XR5 will need to match traffic tagged with 200 from CE2. You must find a way to manipulate frames so that the service works seamlessly, and CE1 and CE2 form an adjacency with no configuration changes on the customer routers.
Answers
At a high level, you will need to enable iBGP-LU between R1/R2/XR4/XR5, and advertise R1 and XR5’s loopbacks.
To do this on IOS-XE you will use the neighbor send-label command, and neighbor next-hop-self all on the ASBR (R2). On IOS-XR you use allocate-label all and ibgp policy out enforce-modifications on the ASBR (XR4). Advertise each router’s loopback on that router (R1 advertises its own loopback and XR5 advertises its own loopback).
Make sure that R2 and XR4 are RRs. R2 should treat R1 and XR4 as clients, and XR4 should treat R2 and XR5 as clients. This allows the PEs loopbacks to be learned via iBGP and then reflected to an iBGP peer.
Once that is complete, R1 and XR5 should have a labeled path to each other. From there you can setup an xconnect as normal.
I purposefully do not have the full config pasted here. If you have trouble I would recommend going through the relevant articles on this website, such as the article on Unified MPLS and E-Line on IOS-XE.
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