[c-nsp] EoMPLS ?s

[Ge Moua]

Once upon a time, we too did this between two sites about 90 miles apart 
with:
* a transport in the middle with a partner/service provider doing MPLS CsC
* on the edge sites with EoMPLS

lesson learned:
* as previously mentioned already, do as large MTU as possible for all 
transit links
* large MTU at the core

we had a situation where we forgot to enable jumbo frame one of the core 
transit links & needless to say traffic traversing that path was being 
dropped if pkt size was greater than that specify MTU (which was just 
the default of 1500); fix was to enable jumbo frame there too then all 
was working

MPLS is pretty unforgiving in that area (also as previously mentioned)

--
Regards,
Ge Moua
Univ of Minn Alumnus
--


On 10/12/11 3:02 PM, Arie Vayner (avayner) wrote:
> Jason,
>
> There is no fragmentation in MPLS. Either you can forward the packet, or
> it is dropped.
> You need to either have a larger MTU on the core (usually the way it is
> implemented today), or reduce MTU at both sides.
> As this is a L2 link, you can't use things like MSS adjust etc...
>
> Arie
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jason LeBlanc
> Sent: Wednesday, October 12, 2011 20:53
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] EoMPLS ?s
>
> We're considering using EoMPLS port mode to bridge two datacenters
> together temporarily for a move using sup720-3BXL on both ends with 6724
> blades, probably 2 or 4 gig links, possibly 10g if I can get them to buy
> the HW.  The question I have primarily is with regard to MTU.  I have
> heard there are issues with ensuring both sides match, not much concern
> there.  But the network between the two facilities may be lower than the
> 1518 bytes, causing fragmentation.  I know this gets punted to the RP,
> and is going to be a problem.  Is there any work around?
>
> Thanks,
> Jason
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