[c-nsp] MPLS best practices question

[Christopher E. Brown]

On 6/23/10 7:41 AM, Mark Tinka wrote:
> On Wednesday 23 June 2010 08:31:03 pm Peter Rathlev wrote:
> 
>> We generally use the highest supported MTU (often 9216
>>  bytes) on all internal links, in an effort to make an
>>  eventual transition easier later.
> 
> We initially considered this, but when some platforms talk 
> 9,216 bytes, others talk 9,198 bytes, others talk 9,000 
> bytes (I think we even saw one that talked 10,000 bytes, but 
> I stepped far away from that box), standardizing at 9,000 
> bytes was sane for us.
> 
> Cheers,
> 
> Mark.


That only works until aq high $$$ customer starts demanding 9000byte
payloads for their IP in vrf or VPLS service...


Seems like 9000 payload is a common target for *customer* jumbo use
these days.


Better to open all the switches wide (9216 payload for most core gear),
and crank your IP and MPLS L3 stuff to the highest all the gear has in
common.

9170ish for IP/MPLS seems to be workable across many platforms and link
types.


(Think customer is feeding double tag ether traffic into a EoMPLS tun
and still demanding 9000 inner payload, and throw TE on top...)