Controlled rollout of MPLS in existing network

RouterOS Forwarding Protocols
1

Good Day,

I’m attempting to deploy MPLS in our network for TE-tunnels and VPLS.

In lab everything works fine and does what we require, in our live network I’m facing some deployment challenges. The first site we activated were our two NOCs and the tower that connects them. What happened is hosts behind NOC A could not access sites past NOC B. We got TTL expired and traceroutes did not get further than NOC B.

The entire network is running OSPF with redistribute-connected=as-type-1,

/mpls ldp
set enabled=yes lsr-id=200.X.Y.Z transport-address=200.X.Y.Z
/mpls ldp interface
add interface=ether1

MTU on the interfaces is 1542 for the existing EoIP tunnels we use for WAN circuits.

Traceroute seems to indicate a loop between the between tower and NOC B.

What should we be checking to find the problem here? We have to deploy the network in parts and have chosen to start at the NOCs, connecting them together first and then work our way out following the OSPF mesh. I believe this may have something to do with Penultimate hop popping but I’m drawing a blank as to what exactly I’m doing wrong.

  • David
2

We do a lot of MikroTik MPLS rollouts and typically if everything works as expected in the lab but fails in production, it usually means there is an MTU problem hiding somewhere. Verify that all network gear in the label switch path can support a frame size equal to or larger than the MPLS MTU you are setting. Also take care of low hanging fruit like making sure the production RouterOS version matches what you used to validate in the lab.

3

Hmm, seems you might be right.

One of the backhauls is a mimosa b5c, the other is a (really old, but rock solid stable) AF 24.

The mimosa MTU is confirmed at 3200, the air fiber is supposed to be 9000 but I seem to be hitting the issue from this forum post:

https://community.ubnt.com/t5/airFiber/AF24-MPLS-Issue/td-p/1099827

I’m going to try some other air fibers which we bought recently and see how it goes.

Thanks for your time.