I have 2x 2611 routers configured for BGP (the same ASN). The routers are in the same switch. One of the routers keeps the BGP routes learned from the other for only1 minute, then they disappear. After another 1 minute, they "come back". This behaviour repeats forever. There are no such problems with other BGP sessions (with the providers). Syslog doesn't show any error either.