IOS XR Rewrite Not Working | Migration from XE Issues

[TrivialPants]

Hi Community,

I am seeing some issues when attempting to migrate some l2vpn circuits from IOS XE to IOS XR. 

The layout is as follows:


(INT VLAN 1) ---- [IOS CPE 3650 CX] ---- (int gi0/1/1, service instance 1 ethernet encapsulation dot1q untagged) [IOS XE PE, ASR 900] ----> l2 mpls virtual circuit <---- [IOS XR P, ASR 9006] ---- (INT BUNDLE 2.5 dotq 5 rewrite ingress tag pop 1 symmetric) [IOS XR EDGE, ASR 9006] --- (INT BUNDLE 10.5 dot1q 5 )   


My l2vpn / mpls pseudowire is established (showing up on both the 9006 and 900 transport routers) but the layer 2 is not establishing. I see the following error messages on my CPE when it establishes:

Feb 17 20:21:32.245: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 5 on GigabitEthernet1/0/8 VLAN1.
Feb 17 20:21:32.245: %SPANTREE-2-BLOCK_PVID_PEER: Blocking GigabitEthernet1/0/8 on VLAN0005. Inconsistent peer vlan.
Feb 17 20:21:32.245: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking GigabitEthernet1/0/8 on VLAN0001. Inconsistent local vlan.
Feb 17 20:21:32.248: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down


It as if the rewrite to untagged is not taking effect properly on the transport IOS XR router and it is still sending the VLAN 5 to the CPE router. 


If I use this same setup, but instead use an IOS XE router for the P router, I do not have the errors, and I can establish layer 2 back to the edge router. 

[MHM Cisco World]

as I know the L2VPN not support untage VLAN. 

[TrivialPants]

I also have tried it this way:

(INT VLAN 1) ---- [IOS CPE 3650 CX] ---- (int gi0/1/1, service instance 1 ethernet encapsulation dot1q untagged, rewrite ingress tag push dot1q 5) [IOS XE PE, ASR 900] ----> l2 mpls virtual circuit <---- [IOS XR P, ASR 9006] ---- (INT BUNDLE 2.5 dotq 5) [IOS XR EDGE, ASR 9006] --- (INT BUNDLE 10.5 dot1q 5 )   


I will get the same message, but if I move back to an IOS XE A900 being the P router, with the equivalent config, it will establish.

[MHM Cisco World]

rewrite ingress tag push dot1q 5 symmetric <<- add symmetric to push,  

[TrivialPants]

Hiya - sorry I left that off of my description. I double-checked and I do have the 'symmetric' keyword on my command already. Good catch, though.

[TrivialPants]

I am mainly running into this issue on those that are looking for encapsulation untagged from the customer side, then trying to rewrite to a tagged interface on our P or PE routers. 

[MHM Cisco World]

show evpn internal-label <<- can I see it in IOS XR (P) ?

[TrivialPants]

That output is blank, but I believe it is because we are using the l2vpn configuration for our p2p circuits. 
Here is an example for the circuit on each:

P (IOS XR)

l2vpn
 xconnect group all
   p2p Test
   interface Bundle-Ether8.5
   neighbor ipv4 1.2.3.4 pw-id 5
   !
   description /30 Xconnect from P to PE
  !

interface Bundle-Ether8.5 l2transport
 description /30 Xconnect from P to PE
 encapsulation dot1q 5
 mtu 2012
!

PE (IOS XE)

interface GigabitEthernet0/1/1
 description Test Xconnect /30 from PE to P
 mtu 1998
 no ip address
 shutdown
 negotiation auto
 no keepalive
 service instance 1 ethernet
  description Data xconnect
  encapsulation untagged
  rewrite ingress tag push dot1q 5 symmetric
  xconnect 4.3.2.1 5 encapsulation mpls
 !

[Ratheesh mv]

Hope (INT VLAN 1) ---- [IOS CPE 3650 CX] is having access port. If it is access port then it always expect IEEE BPDU from far end.

When processing received BPDU on access-port, it must be IEEE standard BPDU otherwise a type inconsistent state is declared. 

[TrivialPants]

Thanks everyone - it is a VLAN 1 interface. The remote side is a different tag, but I am trying to perform a tag swap using the PE router EFP. 

This is accepted & works without issue to transition the VLAN to untagged on IOS XE, but when I use the IOS XR to do the same thing, the issue occurs. 

[diefierr]

@TrivialPants 

I think right from the beginning this is working, seems to me your problem is with STP.
What type of STP do you have on both sides?

Diego

[TrivialPants]

Hi @diefierr , 

We have the default STP settings. On the CPE, we are running rstp. We are also running rstp on the remote side. 

[diefierr]

Right, so you trying to connect vlan "1" with vlan 5, and while traffic will work just fine, you having an STP problem. Is it possible to you to try filtering STP packets on each side? Or at least try doing it on IN / Out on XR side with an ethernet filter.

Diego

[TrivialPants]

@diefierr I am not immediately familiar with this, but I imagine it is possible. I will follow up shortly once I have done some testing. 

Do you have any examples to go off of that I can use as a boilerplate?

[diefierr]

@TrivialPants  take a look on:

https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k-r7-5/lxvpn/configuration/guide/b-l2vpn-cg-asr9000-75x/ethernet-features.html

Diego