SSH session hangs

I have a problem working with ssh connection with OpenSuse as client and FreeBSD as server.

OpenSuse version 11.0
FreeBSD versions 6.4,7.0,7.1

I face with a pause of input/output which resume after 10-60 sec. Such events can repeat every 1-5 minutes. They are quite random: for example connection can hang while I typing something in a text editor or in the shell. There is no load at this time at the local and remote computers (according to top), connection is ok (according to ping). All SSH connections to server hang and resume at one time. However I have no problems with putty client under windows and combinations linke Suse->other servers.

Please, help me to fix it…
Sorry for my bad english and possible lack of information