Why Port Mode EoMPLS ??

Unanswered Question
Jan 8th, 2008

Hi All,

I m confused in what way port mode EoMPLS will be used ?? Because as far i know port mode EoMPLS will need more Port Density in the PE routers as far SP is concerned. In that case they can go for Ethernet VLAN EoMPLS. One thing Port Mode would provide is more Bandwidth. Is there any other advantage of using Port Mode as for SP is concerned??

thanks in advance....

I have this problem too.
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marikakis Wed, 01/09/2008 - 02:06


I have had this discussion with colleagues recently. We were breaking our heads to find out the benefits of this mode, but we just couldn't. :-)

I totally agree with you. Seems to me that this mode was meant to ease early deployment of the technology from the point of view of the network equipment manufacturers, can't think of anything else. It just does not make much sense to me to waste a whole router port, because the bandwidth gained for the customer is simply not enough advantage. Unless you plug the customer directly to the router with no switch between, provider still has to speak VLANs internally in most cases, so only customer gains just a bit. There are surely more cost effective ways to achieve the same thing.

Kind Regards,


etienne.basset Thu, 01/10/2008 - 10:26


in port mode you will forwad every ethernet frame over the pseudowire (every vlan). If the CE router/switch connected to both end of the PW wants to add a vlan, they don't have to contact SP to create a new PW for that vlan, it will be transported


joseph-chapman Sun, 01/13/2008 - 13:18

Etienne had the best answer, but I'd like to elaborate.

That chief advantage, as Etienne said, is that every frame is forwarded. So don't think in just terms of IP. Many platforms had issues and must deal with other L2 control plane protocols -- proprietary or not.

If every ethernet frame is seen as 'payload' and no interpretation of that frame is made, the 'router' providing port-mode EoMPLS is now behaving like a simple, learning switch.

Yes, this is initially a more expensive way to do things but as time goes on, port-costs go down and we will be able to take advantage of these capabilities. Today, if you want to do it 'on-the-cheap', you end up using some kind of SP VLAN (whether q-in-q or not) which means that you are more likely to run into STP issues and so on.


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