[c-nsp] ASR920 Service Instance - when to 'rewrite ingress'

Vinod Kumar Balasubramanyam (vinbalas) vinbalas at cisco.com
Thu Aug 20 00:37:19 EDT 2015

Hi Eric,

Your understanding is right. I'm out of office this week, let me get back
to you next week to figure what the issue is.


Vinod Kumar Balasubramanyam

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On 8/19/15, 6:39 PM, "cisco-nsp on behalf of Eric Van Tol"
<cisco-nsp-bounces at puck.nether.net on behalf of eric at atlantech.net> wrote:

>Hi all,
>Ran into an issue we haven't seen before, primarily due to a
>misunderstanding of when to use 'rewrite ingress tag pop 1 symmetric'.
>We turned up a new ASR920 and had some trouble getting traffic to pass
>between service instances on different interfaces.  Here's the config we
>interface GigabitEthernet0/0/6
> mtu 9216
> no ip address
> load-interval 30
> negotiation auto
> service instance 243 ethernet
>  description SI243
>  encapsulation dot1q 243
>  bridge-domain 243
> !
>interface GigabitEthernet0/0/23
> mtu 9216
> no ip address
> load-interval 30
> negotiation auto
> service instance trunk 1 ethernet
>  encapsulation dot1q 243,1958,1961,1969,1976,2305
>  bridge-domain from-encapsulation
> !
>We had two issues here.  The first issue was that no traffic was coming
>in over Gi0/0/23 - no MAC addresses being learned on any of the VLANs.
>Service instance 243 on Gi0/0/6 *was* learning MACs.  The MAC learning on
>the upstream port was resolved by adding 'rewrite ingress tag pop 1
>symmetric', but then traffic wasn't passing from the SI on 0/0/23 to the
>downstream SIs until adding the same config line in each of the
>downstream service instances.
>I always was under the impression that 'rewrite ingress tag' was used for
>either translation or termination of the VLAN on the local node, but
>unnecessary when transparently passing traffic between SIs on different
>interfaces.  Is this wrong?
>cisco-nsp mailing list  cisco-nsp at puck.nether.net
>archive at http://puck.nether.net/pipermail/cisco-nsp/

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