Jack Bowling wrote:
On Mon, Aug 02, 2004 at 08:53:58PM -0400, Ben Vitale wrote:
Hi,
Yes, I realize this is an often asked question, and for that I apologize. I have the two lines..
alias net-pf-10 off alias ipv6 off
..in my /etc/modprobe.conf, and I have restarted several times since they were put in place. They have had no effect, and I don't think IPv6 is the culprit anyway.. my ifconfig shows all regular IP addresses. I checked the ping times of my nameservers, and the one at the top of /etc/resolv.conf has the best times - on average, 8.5ms. I would assume this is just a Comcast provider problem, but this was not an issue until I upgraded to FC2.
Ben - I wonder if it is a problem with ECN on the nameserver or somewhere on the route? First check to see if you have ECN turned on in your kernel:
cat /proc/sys/net/ipv4/tcp_ecn
If you get a 1 back, it is turned on. As a test, turn it off by:
echo 0 > /proc/sys/net/ipv4/tcp_ecn
and see if the slow ping still happens.
BTW, Ian Gulliver wrote a useful program called ecncheck which tests ECN along a route. There is also a companion program called ecnmx which
compiles from the same tarball that does the same for mailservers. Look for
it on freshmeat.net
Without any changes to kernel 2.6.6-1.435.2.3,
[bvitale@vandelay ~]$ cat /proc/sys/net/ipv4/tcp_ecn 0 [bvitale@vandelay ~]$
[bvitale@vandelay ~/ecncheck]$ ecncheck 68.48.0.6 53
With ECN: Connection accepted by ns02.rtchrd01.md.comcast.net [68.48.0.6] at hop #7
Without ECN: Connection accepted by ns02.rtchrd01.md.comcast.net [68.48.0.6] at hop #7
WARNING: Host doesn't support ECN but fails gracefully
[bvitale@vandelay ~/ecncheck]$
Not sure how to interpret that?
Also, do you think 8.5ms is "slow" for a DNS server ping?
Ben
