Service Instance Creates Loop

[alpha76]

Hi,

My customer has created vlan100, which is dedicated to network management, and we have allowed them to monitor some of the interfaces on the ASR920s. Therefore I created a new instance, encapsulated dot1q 100 and created a bdi. However, after 5 minutes, their network seems to flood with broadcast packets until the service instance is removed.

eg

interface gi0/0/0
service instance 100 ethernet
encapsulation dot1q 100
bridge-domain 100

int bdi 100 
IP address 172.16.1.0 255.255.0.0

My configuration did not include the command 'rewrite ingress tag pop 1 symmetric' because, from my understanding, the traffic does not need to enter the mpls network. However, without this command, it creates a loop.

I have included a basic topology and would like to know if anyone can help me understand why this would happen.

Many thanks

[filopeter]

Hi, POP operation is mandatory for IP termination (BDI interface).

Without rewrite command an untagged packet might left the bridge-domain 100 and being processed by default vlan on CUSTSW switches, which could lead to a loop.