네트웍이 자꾸 죽습니다.

wow 7.3 사용하던 서버가 네트웍이 자꾸 죽어서 콘솔에서 network restart 명령으로 살려서 쓰다가

서버도 바꾸고 OS도 cent os 5.0 으로 바꾸었습니다.
그리고 스위치도 D-link 사용하다가 cisco 로 바꾸었습니다.

그런데 또 그런현상이 나고 있습니다.

아래는 죽을대 즈음의 messages  내용입니다. 네트웍죽은시간은 09:39 입니다.

Jul 31 09:25:50 svc proftpd[778]: test.com (192.1.1.1[192.1.1.1]) - FTP session opened.
Jul 31 09:29:14 svc proftpd[1813]: test.com (192.1.1.1[192.1.1.1]) - FTP session opened.
Jul 31 09:29:28 svc proftpd[1814]: test.com (192.1.1.1[192.1.1.1]) - FTP session opened.
Jul 31 09:34:18 svc proftpd[3395]: test.com (192.1.1.1[192.1.1.1]) - FTP session opened.
Jul 31 09:34:47 svc proftpd[3399]: test.com (192.1.1.1[192.1.1.1]) - FTP session opened.
Jul 31 09:47:55 svc avahi-daemon[2392]: Withdrawing address record for 211.233.10.120 on eth0.
Jul 31 09:47:55 svc avahi-daemon[2392]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.1.1.2.
Jul 31 09:47:55 svc avahi-daemon[2392]: iface.c: interface_mdns_mcast_join() called but no local address available.
Jul 31 09:47:55 svc avahi-daemon[2392]: Interface eth0.IPv4 no longer relevant for mDNS.
Jul 31 09:47:55 svc avahi-daemon[2392]: Withdrawing address record for fe80::21b:cdff:fefe:5d03 on eth0.
Jul 31 09:47:55 svc avahi-daemon[2392]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::21b:cdff:fefe:5d03.
Jul 31 09:47:55 svc avahi-daemon[2392]: iface.c: interface_mdns_mcast_join() called but no local address available.
Jul 31 09:47:55 svc avahi-daemon[2392]: Interface eth0.IPv6 no longer relevant for mDNS.
Jul 31 09:47:57 svc kernel: ADDRCONF(NETDEV_UP): eth0: link is not ready
Jul 31 09:47:59 svc kernel: tg3: eth0: Link is up at 100 Mbps, half duplex.
Jul 31 09:47:59 svc kernel: tg3: eth0: Flow control is off for TX and off for RX.
Jul 31 09:47:59 svc kernel: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
Jul 31 09:48:01 svc avahi-daemon[2392]: New relevant interface eth0.IPv6 for mDNS.
Jul 31 09:48:01 svc avahi-daemon[2392]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::21b:cdff:fefe:5d03.
Jul 31 09:48:01 svc avahi-daemon[2392]: Registering new address record for fe80::21b:cdff:fefe:5d03 on eth0.
Jul 31 09:48:01 svc avahi-daemon[2392]: New relevant interface eth0.IPv4 for mDNS.
Jul 31 09:48:01 svc avahi-daemon[2392]: Joining mDNS multicast group on interface eth0.IPv4 with address 211.233.10.120.
Jul 31 09:48:01 svc avahi-daemon[2392]: Registering new address record for 211.233.10.120 on eth0.
Jul 31 09:50:02 svc xinetd[2173]: START: telnet pid=7742 from=192.1.1.1
Jul 31 09:50:30 svc xinetd[2173]: START: telnet pid=8179 from=192.1.1.1

이렇게 네트웍 죽는 현상의 원인이나 원인파악하기 위한 방법같은것 알고 계신분 도움 요청드립니다.