PDA

View Full Version : [ubuntu] Ubuntu slower on Verizon FIOS than Comcast Cable.



ShawnMilo
January 20th, 2011, 12:42 AM
At work we have a FIOS connection and a cable modem. For some reason, Ubuntu is extremely slow on the FIOS.

Especially slow are loading Web pages and making ssh connections.

Example:
FIOS: 56 seconds to make an ssh connection
cable modem: less than one second

This is despite the fact that running an Internet speed test shows that my FIOS is much faster than my cable modem in both upload and download speeds.

I'm consistently getting this on two completely different Ubuntu machines, a desktop (quad-core) and an Acer laptop. Both are running Ubuntu 10.10.

Windows and Mac computers in our office do not experience this problem.

What should I be looking at to diagnose this?

Thanks,
Shawn

SeijiSensei
January 20th, 2011, 03:47 AM
At first glance it sounds like a DNS problem. When you connect via FiOS what is the contents of /etc/resolv.conf? How about via Comcast?

Try using SSH with IP addresses rather than host names. Any faster? Sometimes reverse name resolution (IP address --> Hostname) isn't properly configured; SSH hates that.

ShawnMilo
January 20th, 2011, 04:09 PM
Thanks a lot for the reply.

No, doing an ssh connection via the IP address isn't any faster. Also, the problem is the same whether it's WiFi or ethernet.

I got the resolv.conf info from both machines -- one of them connected via WiFi and the other connected directly to ethernet. Both gave the same output.

FiOS (both machines, WiFi or ethernet):
# Generated by NetworkManager
domain home
search home
nameserver 192.168.1.1
nameserver 208.67.222.222

Comcast (both machines, WiFi or ethernet):
# Generated by NetworkManager
nameserver 208.67.222.222
nameserver 208.67.220.220
nameserver 10.1.10.1



Update:
A co-worker is still using Ubuntu 9.04. He's not experiencing the same problems I am. On FiOS, here's his resolv.conf:

# Generated by NetworkManager
domain home
search home
nameserver 208.67.222.222
nameserver 208.67.220.220



Update update:
If I manually change my resolv.conf to match my co-worker's 9.04 version, the problem goes away.
So, how do I ensure that it always gets created "properly"?

SeijiSensei
January 20th, 2011, 06:12 PM
Edit as root /etc/dhcp3/dhclient.conf. You'll find a line like this:



request subnet-mask, broadcast-address, time-offset, routers,
domain-name, domain-name-servers, domain-search, host-name,
netbios-name-servers, netbios-scope, interface-mtu,
rfc3442-classless-static-routes, ntp-servers;


Remove the "domain-name", "domain-name-servers", and "domain-search" entries, save the file, and restart the connection. dhclient should no longer touch your /etc/resolv.conf file.

SeijiSensei
January 20th, 2011, 06:13 PM
Damn, I tried really hard to avoid a double post here, too!

ShawnMilo
January 20th, 2011, 06:21 PM
Stupid forums keep hanging and pretending to break, then actually posting double later. Oops.

ShawnMilo
January 20th, 2011, 06:28 PM
Thanks once again for your expertise.

In the end I found a simpler solution. In "Network Connections" I just changed the IPv4 setting from "DHCP" to "DHCP address only," and entered the DNS server IP addresses.

That fixes it and survives a reboot.

I wouldn't have figured that out without you pointing me towards /etc/resolv.conf, so thanks!

Shawn