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Layer 2 VPN ( MPLS, EVC) questions

Unanswered Question
Jun 28th, 2014
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Hi everybody

We have a customer for whom  we provide layer 2 transit between its two locations using mpls as shown below

( I am omiiting a lot of details, just focusing on the main question that i have )


CE1( sanjose)-----gig 0/1-router1---Mpls cloud--------router2------CE2 ( LA)


There is packet loss going on , I am trying to isolate the portion causing all this loss. This is layer2 vpn so we can not use ping.

Focusing on router 1, that is how the traffic from CE1  flows:

Traffic from CE1 is received with vlan tag 449, on service instance 449, where we strip the tag on ingress, and sends it over PW across MPLS core to router 2 as shown below

 

int gig 0/1

service instance 449 ethernet
 
 encapsulation dot1q 449
 rewrite ingress tag pop 1 symmetric
xconnect 192.168.1.1  456  encapsulation mpls


I am going to run following test


CE1 is assigned 10.10.10.1

 

On my router1

I first verify there is no bridge-domain 22 exist, verify no vlan 22 exist

Then i configure the following:


router1
vlan 22

bridge-domain 22


int vlan 22
ip address 10.10.10.2/30


int gig 0/1

service instance 449 ethernet
 
encapsulation dot1q 449
rewrite ingress tag pop 1 symmetric
bridge-domain 22

xconnect 192.168.1.1  456  encapsulation mpls

 


My understanding is that is how traffic from CE1 to 10.10.10.2  flows now:

 CE1 issues ping destined to 10.10.10.2, Frames with vlan 449  from CE1 ,accepted on service instance 449 on gig 0/1, tag is removed, then mac-table of bridge domain 22 is looked up, since the destination mac is mac address of int vlan 22, the frame is then forwarded to int vlan 22 , router1 will simply  send the ping reply back to CE1. Xconnect 192.168.1.1.456 encapsulation mpls will not cause any issue as the mac-address in pings from CE1 points to int vlan 22 not to xconnect 192.168.1.1 456 encapsulation mpls when the mac-table of bridge domain 22 is looked up.

Am i correct ?or do i have to remove xconnect 192.168.1.1 456 encapsulation 456 command in order for pings from CE1 to Router1 work ?

 


+++++++++++++++++++++++++++++++++++++++++++++++++++++++

 

Order of operations:

 

Below I am trying to understand the order of operation . Please consider the following example

 

Router 1:

f0/0

service instance 2020 etherne
  encapsulation dot1q 222
  rewrite ingress tag pop 1 symmetric
 
 bridge-domain 123

  xconnect 1.1.1.1  234 encapsulation mpls
   mtu 1500


Let say router1 receives a packet with vlan tag 222,router1 removes the tag, what will Router1 do next ?  Will router 1 first check tha mac-table of bridge-domain 222  to match destination mac in the packet? OR will router 1 simply send the packet over PW to 1.1.1.1 ?

 

Thanks

 

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