I have a server with dual nic's running centos 5.2 1 nic connects to the cable modem, which has 15m d and 2m up, but speed tests barely come back at 5mb down including road runner's internal speed test. I hook up my laptop to the same modem, same port, using the same cable and I get 17mb down. I have ruled out iptables, nics (because same result on both nics), cables, cable modem(with a brighthouse rep) any suggestions would be greatly appreciated. Thanks.
David Petruzzella Wrote:
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of David Petruzzella Sent: Monday, September 08, 2008 10:09 PM To: centos@centos.org Subject: [CentOS] Need help with an odd issue I am experiencing
I have a server with dual nic's running centos 5.2 1 nic connects to the cable modem, which has 15m d and 2m up, but speed tests barely come back at 5mb down including road runner's internal speed test. I hook up my laptop to the same modem, same port, using the same cable and I get 17mb down. I have ruled out iptables, nics (because same result on both nics), cables, cable modem(with a brighthouse rep) any suggestions would be greatly appreciated. Thanks.
********************************************** JohnStanley Writes:
Maybe trying the vender specific drivers for the Nic Card in question on the CentOS Server may solve the problem. Or a possibilty is if your Bonding or teaming the nics there may be configuration issues in the way you have them set up. Try just one Nic card by itself with out Bonding. You can use "miitool" to set or force the transfer rate of the nic in question; see "man miitool" Since you do say you have dual nics try them both separtly like I stated (Without The Bonding).
JohnStanley
I have a server with dual nic's running centos 5.2 1 nic connects to the cable modem, which has 15m d and 2m up, but speed tests barely come back at 5mb down including road runner's internal speed test. I hook up my laptop to the same modem, same port, using the same cable and I get 17mb down. I have ruled out iptables, nics (because same result on both nics), cables, cable modem(with a brighthouse rep) any suggestions would be greatly appreciated. Thanks.
So I gather the nics aren't teamed from your wording, maybe MTU is set sub optimal for your particular ISP? What OS on your laptop? Wrong MTU can have a significant effect such as this.
jlc
On Mon, 2008-09-08 at 23:46 -0600, Joseph L. Casale wrote:
I have a server with dual nic's running centos 5.2 1 nic connects to the cable modem, which has 15m d and 2m up, but speed tests barely come back at 5mb down including road runner's internal speed test. I hook up my laptop to the same modem, same port, using the same cable and I get 17mb down. I have ruled out iptables, nics (because same result on both nics), cables, cable modem(with a brighthouse rep) any suggestions would be greatly appreciated. Thanks.
So I gather the nics aren't teamed from your wording, maybe MTU is set sub optimal for your particular ISP? What OS on your laptop? Wrong MTU can have a significant effect such as this.
"Back in the day..." there used to be a utility that would test your connection for the optimal MTU setting. Is there something like that for Linux?? Ric
I have a server with dual nic's running centos 5.2 1 nic connects to the cable modem, which has 15m d and 2m up, but speed tests barely come back at 5mb down including road runner's internal speed test. I hook up my laptop to the same modem, same port, using the same cable and I get 17mb down. I have ruled out iptables, nics (because same result on both nics), cables, cable modem(with a brighthouse rep) any suggestions would be greatly appreciated. Thanks.
David,
IME, it is typically (yet not always) a duplex and/or speed issue between the NIC port and the switch or device it is talking too.
man ethtool
ethtool eth0
and check to see what speed and duplex are currently in use...
if duplex and/or speed are off I typically hard code a *managed* switch and the centos box on whatever ports as necessary by adding this line or one similar to it
ETHTOOL_OPTS="speed 100 duplex full autoneg off"
To this and other interface files as necessary
/etc/sysconfig/network-scripts/ifcfg-eth0
At this point a reboot will take care of it or if you don't want to reboot now, Then I would make a little script called downup.sh
ifdown eth0 ifup eth0
and then I chmod 750 that script and then call it like this if from remote
./downup.sh &
So I don't lose connectivity...
There is probably a more elegant command like way to do that...
Be careful if remote box and YMMV
- rh
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David Petruzzella -
John -
Joseph L. Casale -
Ric Moore -
RobertH