BGP problem to expire holdtimer

[Maria Jan Matějka]

>3) so i was thinking that before closing itself bird send a signal to
>other
>bird connected (i didn't search in the code) so i use the command "sudo
>kill -9 *pid*" on the pid of the bird relative to H3, but with a big
>surprised i see that not only the process associated with H3 is killed
>but
>it will be closed the process of H2 H3 and H4

Have you looked into the logs? There should be written why these processes are also down. Or you should somewhere collect their status to see whether they ended correctly or failed somehow. 

Maria