%BGP: This may cause traffic loop if not used properly (command accepted) , isn't a problem?

[Diego Maturana]

Good morning to all,

Actually in my job we are modifiying the configurations from IOS  15.4(3)M3 running in two CE routers 2951. We are adapting to IOS XE 15.5(3)S6 running in two CEs routers ISR 4321. There are a backdoor link between them.

We use "eBGP multipath 2"  for data traffic, until now, that was doing in a sub-VPN because the option wasn't present in GRT.

With the new equipments we don't to do it in a sub-VPN because the option is available in GRT.

I adapted the configurations , everything is working , but i got this message implementing our configuration:

%BGP: This may cause traffic loop if not used properly (command accepted).

It's normal???

We are using as-override and SOO in the backbone, so loops in that way are avoid.

I wanna just be sure that this message isn't more than an advertissment to be careful.

Thanks from now for your comments.

Diego Maturana.

[Giuseppe Larosa · Accepted solution]

Hello Diego,

I think it is only a CLI warning message.

As you have noted you are using site of origin and as override on the PE nodes so the risk of loop is not present in your scenario.

 "

%BGP: This may cause traffic loop if not used properly (command accepted).

It's normal???

We are using as-override and SOO in the backbone, so loops in that way are avoid.

 "

In adding the support of the command in the GRT the IOS developers have chosen to provide a warning message as a sort of disclaimer to advice the network administrators of possible risks.

I think you are safe

Hope to help

Giuseppe

[Diego Maturana]

Hi Giuseppe,

Firstly, pretty thanks for your answer.

I thought like you. I'd like to be 100% sure because we are preparing the new configurations model to change a lot of client sites.

I'll just wait for other comments to be  100% sure; and if is like that i'm gonna accept your solution in the community for sure :)

Greets,

Diego Maturana