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New Member

EVC question

Hi my firends,

I would like to ask a question to all of you, may be you can help me to figure out.

When I start to xconnect from ASR to 6500, the configurations are as belows.

What I want to ask is, on ASR, there ise "rewrite....." command that removes the Vlan header and sends the traffic as untagged. But the 6500 side there is no "rewrite ... " command and no EVC mechanism supported as we expect. So when ASR sends the packet as native, how could 6500 matches these traffic? encapsulation command matches the tagged traffic, but coming traffic from ASR is untagged. It is working but, I think It shouldn't work.

As I expect, we shouldn't make the configuration with the "rewrite.... command". Because there is no need to untag the traffic.In order to match the tagged traffic on 6500, we mustn't configure rewrite command.

Could you please help me about this issue? When only configure encapsulation commmand without rewrite command, is the traffic flowing through xconnect, tagged or untagged?

Regards.

6500
-------
interface Port-channel2.3930
encapsulation dot1Q 3930
xconnect 22.22.22.22 103930 encapsulation mpls

ASR
------

interface GigabitEthernet0/1/0/1.3930 l2transport
encapsulation dot1q 3930
rewrite ingress tag pop 1 symmetric
mtu 8918


p2p test
   interface GigabitEthernet0/1/0/1.3930
   neighbor 11.11.11.11 pw-id 103930

3 REPLIES
New Member

EVC question

Can you check what VC Type is negotiated? In IOS, you can check using show mpls l2transport vc detail
command.

Please note, for VC Type 4, VLAN Rewrite happens automatically.

Regards,

Amit.

New Member

EVC question

Thanks for the reply.

Yes this is type 4, but as you said, If I do not configure rewrite command on ASR, does it work anyway? I could not get the logic of this.

When I configure rewrite pop command, the vlan tag is stripped, but on the other side of tunnel, on 6500, the traffic is sent with tag, isn't it?

Would you please explain the history from the begining, if you don't mind?

Thanks in advance.

New Member

EVC question

The following link and RFC 4448 should answer all your queries.

http://d2zmdbbm9feqrf.cloudfront.net/2012/usa/pdf/BRKSPG-2204.pdf

Regards,

Amit.

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