Customer is receiving unexpected traffic through BGP

[morris0117]

Greetings,

The customer has 2 BGP links towards us, separated dual homed (PE1-CE1 & PE2-CE2), who is asking why they are receiving traffic on link No.1 even they have already configured route-map to deny all routes imported from & exported to PE1. They expect to receiving traffic only on link No.2.

The traffic they mentioned is the output of "sh int xxx": 30 second input rate xxxxxxxxx bits/sec, xxxxx packets/sec. 

Besides asking them to confirm whether their route map is set correctly, what other suggestions can we give them?

And what checks can we do on our end?

Thanks, have a good day.

[Georg Pauwen]

Hello,

with 'traffic' you mean just a certain amount of packets received and sent through the interface, I assume. As long as your customer does not receive any routes through that BGP link, the route maps work. Since there is an active BGP connection, and since there is an active link, a certain amount of traffic is to be expected (BGP control traffic, etc.). The only way to not see these counters increase is to shut down the interface.

[morris0117]

Hi @Georg Pauwen , 

I agree with that. But I suppose what they mean is the traffic is too huge to be considered as control traffic since they have a comparison of CE1 to CE2. Even just for studying, I wonder if there's something we can examine and explore.

[MHM Cisco World]

It can your network is become transit AS

Use as-path list to prevent that

MHM

[Georg Pauwen]

Hello,

can you post the config of the router that has the link with the unusual traffic ? Maybe we can spot something...