[a-nsp] 7050SX MPLS ?

[Bryan Holloway]

On 1/26/21 7:35 PM, Mark Tinka wrote:
> 
> 
> On 1/26/21 19:03, Bryan Holloway wrote:
> 
>>
>> Yeah, I've been bitten by that before ...
>>
>> While the SVI /30 is IP MTU 1500, the L2 MTU (for tagging, MPLS, etc.) 
>> is 9200.
> 
> Are you able to either:
> 
>      - Raise the MTU on the SVI, or
>      - Run IP/MPLS on a/the physical port?

So to be clear, I'm currently lab'ing this up on a vEOS instance running 
4.25.0.

I originally had the IP/MPLS on the "physical" et1 and ran into the 
issues I saw.

Tried changing the L3 MTU on the physical interface to 1504 ... no 
change in behavior.

(Side note: I tried changing it to 1508, and then IS-IS dropped, which I 
find very peculiar, because IS-IS, being a L2 protocol, shouldn't be 
affected by the MTU of a L3 interface.)

Next I tried changing et1 to a switchport and moving the L3 stuff to an 
SVI and ran into the same issues. I was at least able to confirm that 
et1 had an L2 MTU of 9214, and the SVI had an L3 MTU of 1500. Tried 
changing that to 1504 ... same behavior.

(Side note #2: I see the same behavior when changing the L3 MTU to 1508 
... IS-IS drops. Very strange.)

Dehr?