How to prevent endless proxy looping

[piston]

Hi.

I have a endless proxy looping problem.

1. problem username format: userid at my-realm@other-realm
2. on the freeradius, i proxy (nostrip) suffix @other-realm to partner's radiator radius server
3. on my partner then proxy back (nostrip) the same username base on @my-realm to my freeradius
4. so this username userid at my-realm@other-realm is bouncing in between my radius and my partner's radius endlessly
5. both my & partner cannot change the way we proxy, because it will impact on other proxy.

Is there has any parameter which i can configure to terminate such proxy traffic?

Thank you