Re: bad IPv6 performance to ftp.netbsd.org?

[Matthias Scheler <tron%zhadum.org.uk@localhost>]

On Sun, Feb 22, 2009 at 06:02:18PM -0500, Greg Troxel wrote:
> I have systems at BBN and at MIT set up for IPv6.  The provider at BBN
> is sixxs.net, and at MIT OCCAID.  I did a cvs update -r netbsd-5 of a
> netbsd-4 tree, and it took forever, as in went nearly 24h and didn't
> finish.  I ran tcpdump and found very strange sack behavior.  With IPv4
> I don't get the odd behavior, and from BBN I don't get strange behavior,
> although when grabbing pkgsrc.tar.gz I get only 275 KB/s with v6 instead
> of 700 KB/s with v4.  From MIT I get 760 KB/s with v4 and with v6 about
> 800 B/s (yes, 800 bytes per second).

My experience with Occaid was very bad in the past. The IPv6 link
from home (UK) to the ISC broke every few weeks. And they would
never fix it unless by ISP (AAISP) proded them.

> Is anyone else seeing poor IPv6 TCP performance?

Not since my IPv6 link to ISC doesn't go over Occaid anymore:

tron@colwyn:~>traceroute6 ftp.NetBSD.org
traceroute6 to ftp.NetBSD.org (2001:4f8:4:7:230:48ff:fe31:43f2) from 
2001:8b0:114:1::5, 64 hops max, 12 byte packets
 1  jumpgate  4.84 ms  4.15 ms  3.831 ms
 2  careless.aaisp.net.uk  18.04 ms  17.023 ms  16.885 ms
 3  aimless.aaisp.net.uk  18.036 ms  19.238 ms  17.653 ms
 4  a.restless.thn.aaisp.net.uk  18.038 ms  19.74 ms  20.343 ms
 5  linx.he.net  23.782 ms  25.088 ms  24.951 ms
 6  10gigabitethernet2-3.core1.nyc4.he.net  88.315 ms  89.132 ms  95.988 ms
 7  10gigabitethernet3-1.core1.sjc2.he.net  165.888 ms  167.105 ms  166.627 ms
 8  10gigabitethernet3-2.core1.pao1.he.net  171.639 ms  167.436 ms  168.925 ms
 9  he.pao1.isc.org  170.098 ms  181.455 ms  166.826 ms
10  int-1-2-0-800.r2.sfo2.isc.org  169.345 ms  169.353 ms  168.551 ms
11  sfo2-sql1.r1.sql1.isc.org  168.999 ms  178.828 ms  171.612 ms
^C

[The reason for the lack of response for the last hop is the
 packet filter on "ftp.NetBSD.org".]

        Kind regards

-- 
Matthias Scheler                                  http://zhadum.org.uk/