Hi, we made a very interesting observation. For some reason we downgraded Linux kernel do 2.6.24 and MD5 signed BGP session became unstable. BIRD was able to establish session but later it started to send packets with invalid MD5 signature randomly. This caused BGP session drop sometimes. TSO and scatter-gather were switched off. The problem disappeared after upgrade to 2.6.32. So please be careful with Linux kernel versions. Ondrej