xconnect: how to see mac address table?

Unanswered Question
Sep 29th, 2009

Situation...

interface Gi0/1.2

encapsulation dot1Q 2

xconnect 10.0.0.1 1111 encapsulation mpls

Is there a way to see the Mac Addresses on that subif???

I have this problem too.
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Giuseppe Larosa Tue, 09/29/2009 - 11:58

Hello Steve,

I don't think the device has a MAC address learning function in EoMPLS enabled subif:

when we tested it years ago we generated flows with destination MAC address = interface MAC address and those frames were carried over the EoMPLS link.

This happened on a GSR with 3 GE engine 2 linecard and IOS 12.0(23)S.

I think it just checks the vlan-id and the FCS for this reason it is only a point-to-point L2 transport service.

Hope to help

Giuseppe

Steve Rodrigue Tue, 09/29/2009 - 12:02

So, there is no equivalent to "show mac-address-table" for Subif and/or xconnect stuff???

It might exist something... Maybe diging into the cef table or something like that???

Giuseppe Larosa Tue, 09/29/2009 - 12:12

Hello Steve,

I did some search in a C3750 ME when using port based EoMPLS you can enable mac address learning:

Starting with Cisco IOS Release 12.2(44)SE, when you configure port-based EoMPLS on a Layer 3 interface, you can enter the mac address-table learning interface interface-id global configuration command to enable MAC address learning on the port. This ensures that bidirectional traffic can occur at line rate. However, when MAC address learning is enabled, duplicate MAC addresses across VLANs are not supported. An example would be running HSRP groups across the port-based EoMPLS session.

see

http://www.cisco.com/en/US/docs/switches/metro/catalyst3750m/software/release/12.2_46_se/configuration/guide/swmpls.html#wp1184930

But you are not doing port based EoMPLS

So the scenario is different on multilayer switches.

What platform and IOS are you using?

Hope to help

Giuseppe

Steve Rodrigue Mon, 10/19/2009 - 10:01

Effectively, this command is not possible (C7600):

mac address-table learning interface GiX/Y

:(

Back to start...

Giuseppe Larosa Mon, 10/19/2009 - 10:31

Hello Steve,

from another point of view this lack of address learning on EoMPLS provides more scalability:

there is no risk to fill the CAM table on the L2 PE node.

the price to pay is that you cannot monitor what MAC addresses are seen on the xconnect pseudowire.

Hope to help

Giuseppe

Steve Rodrigue Mon, 10/19/2009 - 10:58

I understand, but that would be great to at least have some way to see those mac-addresses. For example: while testing or to confirm that we do really see a specific mac at the end of the "pseudowire".

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