The MPLS-OPS Archive

[Mark Lewis <markl11_uk@yahoo.co.uk>]

Just to add, if you're talking about Martini draft
layer-2 transport here (AToM on Cisco routers), then
the MTU on core facing router interfaces should be:

Tunnel label(s) + VC label + (Optional Control word) +
layer-2 PDU

So, for example, assuming no TE then: 4 octets (1 IGP
tunnel label) + 4 octets (VC label) + 4 octets
(control word) + whatever size layer-2 PDU you are
transporting. If you are using TE then add 4 octects
if TE tunnels are between P routers, and add another 4
octets if you are using fast re-route.

& then enable Jumbo frame support on Ethernet switches
as has already been mentioned.

Mark



 --- BERKANE Mourad
<mourad.berkane.prestataire@sfrcegetelsi.fr> wrote: > 
> 
> Hello Iasonas,
> 
> Ethernet switches in your MPLS Core network is not
> incompatible, you must
> only enable Jumbo frames when possible.
> (1526 is not always enought!)
> 
> R/
> Mourad
> 
> -----Message d'origine-----
> De: Iasonas Charalambous
> [mailto:iasonasc@cytanet.com.cy]
> Date: vendredi 23 janvier 2004 08:29
> À: mpls-ops@mplsrc.com
> Objet: [MPLS-OPS]: Layer 2 VPNs over switch
> 
> 
> Hi all,
> 
> I heart that Layer2 VPNs have problems when going
> thourgh Etherner 
> switches. Does anyone know if this is the case? I
> know that Layer 3 VPNs 
> have similar problems but they can be handled by 
> changing the MTU size on 
> the switch to 1526 bytes and setting the command
> "mpls MTU 1526" on cisco 
> routers ethernet ports.
> 
> Thanks,
> 
> Iasonas
>
___________________________________________________________________________
> Iasonas Charalambous				email:
> iasonas.c@cytanet.com.cy
> CYPRUS TELECOM. AUTHORITY		TEL + 357 22701609
> Technical Management Internet Services	www:
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> 
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