We are looking at Cisco ME3600 to provide connectivity between our datacenter fabrics for some software defined networking. Due to the platform having a higher limitation on EoMPLS xconnects than VRFs (512 vs 128), we are considering the approach of allocating a vLAN in each DC to a software router, and using EoMPLS to connect these two software routers together to route Layer 3 traffic.

For redundancy, we want to have 2 PWs for each connection between a pair of software routers, and I'm curious how best to have this, given the interactions between various spanning tree implementations.

One of our datacenters has MSTP deployed as a single region, odds in instance 1, evens in instance 2, CIST in instance 0. The other datacenter still operates R-PVST.

The current plan is to create a trunk from the switch fabric into the ME3600, and use a EFP for specific vLANs and assign them to a xconnect. I'm curious how the switch fabric on each end will handle this -- will I have to setup a vLAN 1 EFP on both sides, and pass PVST traffic? Will this be enough to set root/block/alternate on both sides?

Diagram below of the physical layout, and the logical idea behind connecting two software routers.

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1 Answer 1


The ME3600s don't support the forwarding of STP or MST frames through EVC. Port based PWE3s will transport STP frames but you will have to chew up a lot of ports. Really you should be engaging your vendor to platform specific questions like this that are "Will the switch support X feature" or "Does your switch forward X traffic".

I suggest also habinga look at a feature backup pseudowires. That removes the loops at layer 2 at least although doesn't address your problem of no support for STP when using EVCs: http://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/fspseudo.html

It maybe also be that VPLS is a better way to go if it is a small number of peers and traffic. The ME3600s do support VPLS (I suggest runnnig 15.3(3)S3 at the time of writting).


Since I wrote this the command is now present to forward L2 PDUs in the EVC however I haven't tested this:

ME3600-1(config-if-srv)#l2protocol tunnel ?
  R4     Reserved Protocol using DA Mac 0180.C200.0004
  R5     Reserved Protocol using DA Mac 0180.C200.0005
  R6     Reserved Protocol using DA Mac 0180.C200.0006
  R8     Reserved Protocol using DA Mac 0180.C200.0008
  R9     Reserved Protocol using DA Mac 0180.C200.0009
  RA     Reserved Protocol using DA Mac 0180.C200.000A
  RB     Reserved Protocol using DA Mac 0180.C200.000B
  RC     Reserved Protocol using DA Mac 0180.C200.000C
  RD     Reserved Protocol using DA Mac 0180.C200.000D
  RF     Reserved Protocol using DA Mac 0180.C200.000F
  cdp    Cisco Discovery Protocol
  dtp    Dynamic Trunking Protocol
  elmi   ELMI Protocol
  esmc   ESMC Protocol
  lacp   LACP Protocol
  lldp   Link Layer Discovery Protocol
  loam   Link OAM Protocol
  pagp   Port Aggregation Protocol
  ptppd  PTP Peer Delay Protocol
  stp    Spanning Tree Protocol
  udld   UDLD Protocol
  vtp    Vlan Trunking Protocol

2nd Update

Tested and works! The ME3600X/ME3800X are MEF 2.0 compliant devices so this is a required feature.

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