BGP cannot connect

Simple configuration in GNS3 won’t work. All I get from debug is: went from nsf_not_active to nsf_not_active The solution is quite simple: under BGP process and neighbor statement add “disable-connected-check“

MTU traceroute and value check

check your MTU settings with user@computer:~$ tracepath -n 1: 0.099ms pmtu 1500 1: 0.425ms 1: 0.405ms 2: 1.345ms 3: 4.111ms 4: 4.327ms 5: 192.967ms 6: 6.561ms asymm 7 7: 4.719ms asymm 10 8: 6.181ms asymm 9 9: 5.390ms asymm 10 10: 4.403ms

BGP session flapping

my customer is peering with 2 ISP’s and has configuration with 2 BGP routers mutually connected with iBGP. routers are reciving full tables from ISP’s and has 4 byte AS (XXXXXX). recently we noticed that BGP session between customer and ISP2 is constantly flapping each 3 minutes. logs didn’t show anything useful %BGP-4-MSGDUMP: unsupported or mal-formatted