Has anyone seen a situation, where a CPE's advertised route to his eBGP PE, get sent straight back down to the CPE thus causing a loop?
I have it where the PE is setting the Local pref for his own AS to 100 for the inbound prefix, then somehow sending that route back down to the CE with the Local Pref intact. The CPE then thinks this 'new' route with a Local pref of 100 is better, thus causing a loop.
"Allow-as in 1" is turned on as its a MPLS network, but I don't think seeing the echo route with iBGP parameters attached is normal?
Also I labbed this up, on GNS and cannot replicate the route-feedback. Short of reading the RFC does eBGP use a loop prevention mechanism besides AS-Path in order to not advetise a route on a link in which he has just recieved it? My first guess was no, just AS path, but labbing this up, the PE will not advertise it back to the CPE. Anyfeedback appreciated Thanks