Etherchannel over MPLS

Unanswered Question
Sep 1st, 2009

We receive Layer 2 MPLS VPN services from our Service Provider from our main site to our data center a few miles away. When I do a sho cdp nei, I can see the distant end. My question is, can I do a Layer 3 etherchannel configuration between these two devices? My current setup is two 1 gig uplinks from the main site to the Provider Edger router and two 1 gig uplinks from the data center to the Provider Edge router running OSPF, load balancing between the two links.

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axrecinos Wed, 09/02/2009 - 06:49

I've sent them an email asking them about it. Waiting on their reply.

Mohamed Sobair Tue, 09/01/2009 - 13:25

Hi,

I dont think L2VPN will support such setup.

The reason is because l2VPN is a point to point in fashion with two labels , the inner label is the vc label the outer label is the tunnel label , the TTL valus is always set to 2.

If you need to support etherchannel , you will need to have VPLS service from the service provider.

HTH

Mohamed

amit.bhagat Tue, 09/01/2009 - 16:28

Is the SP carrying a complete trunk or individual VLANs over Ethernet Pseudowire?

axrecinos Wed, 09/02/2009 - 06:48

I spoke with a representative from our SP, and he said it is MPLS over Ethernet, carrying individual VLANs

Mohamed Sobair Wed, 09/02/2009 - 12:35

Hi,

Its obvious from your describtion that its Ethernet over MPLS using Ethernet port mode carrying individual vLans.

with the current senario you cant have etherchannel config supported.

HTH

Mohamed

amit.bhagat Wed, 09/02/2009 - 15:41

I wonder if a GRE tunnel is the answer but if you are already load-balancing over two links, the question arises- why bother setting up an etherchannel?

I am interested in knowing how the SP is dealing with these two attachment circuits attached to each PE devices? Surely, there will be two different Ethernet Pseudowires between the two PE devices.

Please enlighten me.

Amit.

Giuseppe Larosa Thu, 09/03/2009 - 03:30

Hello Amit,

I share your doubts: in this scenario moving to an etherchannel link instead of using L3 load balancing shouldn't be a so great change:

L3 load balancing uses CEF and an exor of IP SA IP DA and a a hash that changes at each reload.

an etherchannel when processing IP traffic does exor of IP SA and IP DA (it is possible to change this)

Hope to help

Giuseppe

amit.bhagat Thu, 09/03/2009 - 15:38

Right Giuseppe. So if a GRE tunnel is setup, CEF is used for load-balancing and if a L3 Etherchannel is setup, CEF is NOT used for load-balancing. :)

Can you also confirm the SP will need to setup two Pseudowires here since the SP PE router is connected via two attachment circuits to the CE router?

Regards,

Amit.

Giuseppe Larosa Fri, 09/04/2009 - 05:47

Hello Amit,

yes using one pseudowire for each physical links allows you to carry an etherchannel over two EoMPLS VCs.

to be noted that also with 802.1Q you can do the same using two different customer-ids.

I'm not sure but in my EoMPLS tests I've seen PE node just check the vlan-id of the frame to decide if it has to take it and to put it on pseudowire.

So I would expect etherchannel signalling packets to be carried over the pseudowire.

Hope to help

Giuseppe

Laurent Aubert Wed, 09/02/2009 - 17:10

Hi Mohamed,

Actually, it works:

1- With latest HW and SW on 7600/GSR, you can terminate the etherchannel on the PE. You can apply the xconnect on the port-channel interface but only the ON mode is supported (no LACP or PAGP). It's due to the fact that those packets will be transparently send into the PW which will prevent the PE to build up the etherchannel.

2- Or ou apply the xconnect on each physical interface (one PW per link) which should allow you to have an end-2-end Etherchannel.

HTH

Laurent.

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