EVC | Service instance question

[sarahr202]

Hi everybody

Please consider the following example:

Interface gi1/1
service instance 10 ethernet
encapsulation dot1q 10
bridge-domain 20

INGRESS BEHAVIOR:

Let say  a packet with vlan tag 10 is received on EVC port shown above,

1)What will happen next ?  Will vlan tag 20 be added on the top of existing vlan tag 10 and then MAC table associated with bride domian 20 is looked up for destination mac?

EGRESS BEHAVIOR:

Let say a packet needs to be sent out of above EVC.

1)Will the tag 10 be added when sending packets out of EVC ?

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BRIDE DOMAIN :

Router1:

Interface gi1/1
service instance 10 ethernet
encapsulation dot1q 10
bridge-domain 20

Router 1 has PW to remote PE ( R2); PW to R2 is a part of bride-domain 20 on R1

Router1- ( MPLS CORE)--PW-------R2

Behavior ( packets entering  Bride domain 20 on PW  on R1 from MPLS core):

keeping the above config in mind,please consider the following question:

what vlan tag must be present in order for packets from R2 to be accepted by bride-domain 20?  Should all the packets sent by R2 on PW to R1, must carry vlan tag 20 ?

Behavior( packets leaving bride-domain 20 on PW on Router 1 to reach Router 2)

keeping the above config in mind, please consider the following question:

Will vlan tag 20 be removed before R1 sends packet over PW to R2?

Thanks

[Emmanouil Patiniotakis]

In order to do a vlan rewrite either in ingress packet or egress packets you have to include the rewrite command under the service instance. 

[sarahr202]

Thanks for your response.

We do not need to use rewrite option though it is fairly common,under a service instance for EVC.

[kurtnolfses]

Yes the vlan tag 20 ( S-VLAN 20) will be added on top of the C-VLAN 10. So you will have double tagged frame with outer-tag 20 and inner-tag 10. MAC learning will be done on bridge-domain / vlan 20. Outgoing to R1, the inverse will happen. S-VLAN 20 will be stripped and the packet with tag 10 will be sent to R1.