Hi,
I’ve recently upgraded my 5 year old PC from Suse 10.1 to Suse 11.2. I’ve had Comcast cable internet service at this location since 1997 (back then it was called @Home, but it’s the same network).
Since the upgrade to 11.2, I’ve had problems accessing the internet over my Comcast cable account. Some of these problems I’ve managed to knock down, but a problem with intermittent loss of connectivity during times where I am downloading data has continued.
First I figure I’d document what I’ve done so far which has at least restored some internet access through this account.
Properly Configure DHCP Client Hostname
Suse 11.2 uses the dhcpcd DHCP client. Comcast cable apparently requires that the DHCP client provide a particular hostname when the client is attempting to discover an IP address. I wont specify the “right” hostname in it’s entirety here, but it begins with “C10…”. Fortunately I never throw out anything so I still had the work order from when the service was installed back in 97 and on that work order the correct hostname is printed. In order to make dhcpcd send this hostname option in its Discovers, I set the hostname of the machine to that “C10…” hostname using Yast:
Network Devices->Network Settings
Then click Hostname/DNS table and enter the hostname into the Hostname field. I think I followed that with a reboot.
Now the dhcpcd client is supplying the hostname. This can be verified by running ps to find dhcpcd, cd’ing to it’s proc entry and catting cmdline, as in:
jeff@C100…:~> ps -A | grep dhcpcd
2381 ? 00:00:00 dhcpcd
jeff@C100…:~> cd /proc/2381
jeff@C100…:/proc/2381> cat cmdline
/sbin/dhcpcd–netconfig-L-E-c/etc/sysconfig/network/scripts/dhcpcd-hook-t0-hC100…eth0jeff@C100…:/proc/2381>
That “-hC100…” is the command line parameter to tell dhcpcd to specify the hostname it will transmit. Once this was done, I was able to get an IP address from Comcast. Note I found later that there is perhaps a better to way to specify this under Yast at:
YaST -> System -> Network Settings -> Global Options -> Hostname to Send
That might work, too, I haven’t tried it.
So that got me an IP address, but what I found is that anytime I did anything that generates significant download bandwidth (like Online Update or any other Yast software installation), my network connectivity would eventually go away. The symptom leading up to this would be very slow ping response from the default router, as in:
jeff@C100…:/proc/2381> netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
67.170.240.0 0.0.0.0 255.255.248.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 67.170.240.1 0.0.0.0 UG 0 0 0 eth0
jeff@C100…:/proc/2381> ping 67.170.240.1
PING 67.170.240.1 (67.170.240.1) 56(84) bytes of data.
64 bytes from 67.170.240.1: icmp_seq=1 ttl=255 time=6.34 ms
64 bytes from 67.170.240.1: icmp_seq=2 ttl=255 time=7.51 ms
64 bytes from 67.170.240.1: icmp_seq=3 ttl=255 time=5.93 ms
This example shows “good” connectivity, but when the problems occur, the “time” of the ping response keeps going up and up to around 2 seconds or so and then there’s no response.
At that point, all network activities seem to stop. I’ve found that by power cycling the modem, I can get connectivity back for a while.
Turn Off IPv6
So I read elsewhere in this forum that Comcast doesn’t like IPv6. So I turned off IPv6 globally via Yast:
YaST -> System -> Network Settings -> Global Options -> un-check “Enable IPv6”
and did a reboot. I also disabled IPv6 DNS look ups in Firefox via:
* type about:config in the address bar, and hit the Return or Enter key.
* type ipv6 in the filter field.
* high-light network.dns.disableIPv6 by right-clicking it, and change the value from false to true using Toggle.
This seems to have perhaps improved things in that I seem to now be able to generate more download bandwidth before things lock up, but I still find I have to power cycle this model to get connectivity back.
The modem is a Motorola SB4200 Surfboard Cable Modem.
I am thinking perhaps Comcast doesn’t like that I am on that 168.254/16 zeroconf network, so I think I am going to try to turn that off now, but that’s a Microsoft invention. It seems unlikely that Comcast would require that PC’s running Windows not do their normal thing.
Any suggestions would be welcome at this point.
Thanks,
Jeff Haran
