I don't think it is cable problem. The reason are: 1. it happen every 3 to 4 weeks once. 2. problem last 4 to 5 hours then back to normal. 3. not one server has this problem, several servers on that rack all have problem at same time. --- 11/3/28 (一)，Peter Larsen <plarsen at famlarsen.homelinux.com> 寫道： > 寄件者: Peter Larsen <plarsen at famlarsen.homelinux.com> > 主旨: Re: [CentOS] centos server network speed check??? > 收件者: centos at centos.org > 日期: 2011年3月28日,一,下午5:41 > On Tue, 2011-03-29 at 05:13 +0800, > mcclnx mcc wrote: > > we have several servers on same rack and servers are > all inside firewall. Centos version from 4.X to > 5.X. sometime the connection are very slow (compare to > servers on other racks also inside firewall). > > > > we discuss with network engineer he ask us use "ping" > and traceroute" to check. Both tools response time are > good but if we connect through application like Web browser, > database, or DELL OPMN tool. The response time is very > very slow. > > > > This situation normally last 4 to 5 hours then it back > to normal. Does there has way to check "real" network > response time so we can show to network engineer. > Otherwise they always say "no problem". > > miitool and ethtool > > Check that you're running at the right speed; sometimes bad > cables will > make the negotiation go bad. Sometimes you just connect to > the wrong > switch port. You may also note if the switch has hard-set > values about > the negotiation such as duplex settings. Make sure they > match on both > ends. You should be full duplex unless there's a very very > good network > reason not to. > > Lastly, check ifconfig output. Make sure there's no errors > reported. If > you have a high error count, it's a good bet the cable is > bad or the > sync settings are wrong. > > -- > Best Regards > Peter Larsen > > Wise words of the day: > Showing up is 80% of life. > -- Woody Allen > > -----內含下列夾帶檔案----- > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >