[c-nsp] MPLS EXP on STP Frames (6500)

[Steve Dodd]

IIRC the EXP values for non-IP traffic are mapped directly from the .1p COS
values. Depending on your flavor of STP this field may not even exist, in
which case I suspect it is being treated as COS0. Is it possible to have
the downstream device push a .1q tag?

Cheers,
Steve

On Fri, Feb 9, 2018 at 8:41 AM, Robert Williams <Robert at custodiandc.com>
wrote:

> Hi all,
>
> Is anyone aware of a feature which allows the EXP value on an STP frame to
> be set when it is encapsulated by a xconnect on a 6500?
>
> Example config:
>
> int gi1/1
>   description Customer Port
>   xconnect 1.2.3.4 666 encapsulation mpls
>   service-policy input set-exp-3
>
> policy-map set-exp-3
>  class class-default
>    set mpls experimental imposition 3
>
> I would expect all traffic which ingresses on that customer port to be set
> to EXP 3 when it is encapsulated. This is, unfortunately, not the case....
>
> When the traffic egresses the 6500, it is 'mostly' set to EXP 3 - except -
> a few special things, like the STP frames, LLDP and some other control-type
> stuff. Basically, only the IP stuff gets set to EXP 3.
>
> Control things get various values, STP for example goes to EXP 0 - and
> nothing changes this as far as I can find. I have also noticed some other
> types of traffic are set to other values (like EXP 5,6,7) so clearly there
> are more exceptions than just STP, but I figure that they are probably
> controlled by the same knob/feature, somewhere...
>
> Platform is Cat6500 with S720-10G, X6748 cards and IOS 15.1(2)SY6
>
> It's a specific customer requirement so changing platform isn't an option
> in this case. I've also tried re-writing it (to EXP 3) on egress out of the
> box towards the MPLS core, but this isn't supported on this platform. I
> also tried setting it on the tunnel, but again that is only supported in
> ingress, not egress...
>
> So - any ideas anyone?
>
> Cheers!
>
>
> Robert Williams
> Custodian Data Centres
> https://www.CustodianDC.com
>
>
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