[c-nsp] ASR9K to ASR920 MPLS issue

[Jerry Bacon]

Finally was able to get this all working and tested. As we surmised, it 
works properly either with or without the "rewrite", as long as it's 
symmetrical. So I guess it comes down to a personal or network 
preference. I can see a slight advantage to always doing it, as it 
uncouples the VLAN encapsulation on the two sides.

Thanks again for all your help.

-- 

Jerry Bacon
Senior Network Engineer
StarTouch, Inc.
http://www.startouch.com
360-543-5679 ext. 111
Microwave - Fiber Optics - Internet Services

On 1/12/2021 9:22 AM, Lukas Tribus wrote:
> On Tue, 12 Jan 2021 at 18:02, James Bensley
> <jwbensley+cisco-nsp at gmail.com> wrote:
>>> Can I omit the "rewrite ..." on both sides?
>> Why would you want to? I think that if you do that, a VLAN tagged
>> frame coming into one end with VLAN 95, will be send over the
>> pseudoiwre with the VLAN tag still present, at the other end it will
>> have VLAN 95 push on egress, so it will leave the other end double
>> tagged with an inner and outer VLAN tag of 95.
> I don't believe this is what happens.
>
> "rewrite ingress pop 1 symmetric" <-- the symmetric keyword means that
> it pushes on egress and pops on ingress.
>
> Without "rewrite *" it does neither afaik; therefore, if you have the
> same configuration end-to-end, it works, because the tag is preserved
> as-is and no vlan tags are pushed or popped anyware (just labels, of
> course).
>
> That's said I don't like the configuration without the rewrite keyword
> at all, because it is confusing and redundant to have to include the
> vlan tag, when all you need to transport is a single vlan. And it is
> easier to get configuration mismatches when you do it this way.
>
>
> Lukas