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Service Instance Creates Loop

alpha76
Frequent Visitor
Frequent Visitor

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

 

 

1 Reply 1

filopeter
Level 7
Level 7

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.