I have RHEL5 server

Sometimes ping timeout occured and i can not access server from any tool

or ILOM

Any ideas how to solve this?

From the little you have told us, this sounds like a network problem rather than anything to do with the RHEL server.

here log file in /var/log/messages

Dec 19 12:46:30 testapp avahi-daemon[5269]: Invalid query packet.
Dec 19 12:47:06 testapp last message repeated 2 times
Dec 19 13:26:38 testapp kernel: frmweb[26193]: segfault at 000000006974655e rip 00000000f7d312c1 rsp 00000000ffc49048 error 4
Dec 19 13:58:17 testapp kernel: do_vfs_lock: VFS is out of sync with lock manage r!
Dec 20 06:58:23 testapp avahi-daemon[5269]: Invalid query packet.
Dec 20 06:59:03 testapp last message repeated 7 times
Dec 20 07:37:52 testapp avahi-daemon[5269]: Invalid query packet.
Dec 20 07:38:32 testapp last message repeated 6 times
Dec 20 07:46:29 testapp kernel: do_vfs_lock: VFS is out of sync with lock manage r!
Dec 20 07:47:03 testapp kernel: do_vfs_lock: VFS is out of sync with lock manage r!
Dec 20 07:47:03 testapp last message repeated 7 times
Dec 20 07:48:06 testapp avahi-daemon[5269]: Invalid query packet.
Dec 20 07:48:46 testapp last message repeated 7 times
Dec 20 08:07:29 testapp avahi-daemon[5269]: Invalid query packet.
Dec 20 08:08:13 testapp last message repeated 11 times
Dec 20 08:40:39 testapp kernel: do_vfs_lock: VFS is out of sync with lock manage r!
Dec 20 08:42:28 testapp last message repeated 3 times
Dec 20 08:43:33 testapp kernel: do_vfs_lock: VFS is out of sync with lock manage r!
Dec 20 08:48:12 testapp kernel: do_vfs_lock: VFS is out of sync with lock manage r!
Dec 20 09:30:49 testapp last message repeated 11 times

Sounds like you may have a bad NFS mount. See if you can log into the console directly and unmount any NFS mount points. It may be dangerous to do so in a hung state, but

umount -l <directory>

Sounds like fcntl locks are being released locally but not on NFS server. Is your RHEL server up-to-date with patches?

Thanks for your reply