Solved: Multipoint L2VPN and BVI

ProNtokz · ‎08-14-2019

Hi, am faced with a rather weird one. I have configured a L2VPN between a pair of NCS5501`s, and connected end devices(CPEs) to the attached VLAN. All is working, except connectivity to a BVI interface configured on on one of the routers, from the remote peer and its connected devices.

Find attached a topology of the physical layout.

Here is the Config:

PR-R1

!
l2vpn
pw-class VPLS
encapsulation mpls
!
!
bridge group CUST_SET1
bridge-domain VL10_CloudC
interface GigabitEthernet0/0/0/0.10
!
vfi VL10_CloudC
neighbor 172.31.253.1 pw-id 10
pw-class VPLS
!
!
routed interface BVI10
!
!
!
interface GigabitEthernet0/0/0/0.10 l2transport
encapsulation dot1q 10
rewrite ingress tag pop 1 symmetric

PR-R2

!
l2vpn
pw-class VPLS
encapsulation mpls
!
!
bridge group CUST_SET1
bridge-domain VL10_CloudC
interface GigabitEthernet0/0/0/0.10
!
vfi VL10_CloudC
neighbor 172.31.254.1 pw-id 10
pw-class VPLS
!
!

!
interface GigabitEthernet0/0/0/0.10 l2transport
description CloudC
encapsulation dot1q 10
rewrite ingress tag pop 1 symmetric
!

I cannot reach the BVI interface on PR-R1 from C-R2 or PS-SW2, but I can get to PS-SW1 and C-R1 from these

devices(C-R2 or PS-SW2).

Any ideas, tips, solutions will be much appreciated.

ChasMac · ‎08-17-2019

We have also run into this on a 5501-SE vs. an ASR9001. From what we understand, while the command is accepted into the config (routed interface BVIxxx) it will only work with physical interfaces, not with VFIs.

As explained to us -- due to the Merchant Silicon-based product (the 55xx) - it has a pipeline architecture which means a packet can only pass through the internals once -- eg, in this case -- a VFI termination, or a BVI termination -- but not both.

We ended up doing a "hairpin" as a work-around (a bad kludge - and wasting ports/bandwidth licensing) -- eg, terminate the VPLS on a physical interface (in l2transport mode), and then literally connect that L2 port back into the router itself, and on that port, it is a L3 "ip address" port. We do this as "matching-pair" sub-interfaces on each L2/L3 port to be able to accomplish the same thing as "routed interface BVIxxx"

...Chas

View solution in original post

ChasMac · ‎08-17-2019

We have also run into this on a 5501-SE vs. an ASR9001. From what we understand, while the command is accepted into the config (routed interface BVIxxx) it will only work with physical interfaces, not with VFIs.

As explained to us -- due to the Merchant Silicon-based product (the 55xx) - it has a pipeline architecture which means a packet can only pass through the internals once -- eg, in this case -- a VFI termination, or a BVI termination -- but not both.

We ended up doing a "hairpin" as a work-around (a bad kludge - and wasting ports/bandwidth licensing) -- eg, terminate the VPLS on a physical interface (in l2transport mode), and then literally connect that L2 port back into the router itself, and on that port, it is a L3 "ip address" port. We do this as "matching-pair" sub-interfaces on each L2/L3 port to be able to accomplish the same thing as "routed interface BVIxxx"

...Chas

ProNtokz · ‎08-19-2019

Yes Chas,

This was confirmed to me by Cisco TAC.

Thanks!