Rick Thomas <rbthomas@pobox.com> writes: > On Jun 1, 2011, at 7:16 PM, Rick Thomas wrote: > >> >> I've been noticing the same problem: hangs on IPv6 enabled hosts when >> doing aptitude updates... >> >> The solution is to set the MTU to 1280 > > One way to do that is to edit /etc/network/interfaces and add to the > stanza for the interface that will carry your ipv6 traffic: > mtu 1280 > > This only works if the interface is configured "static". I don't know > how to do it if you are using dhcp. > Thanks Rick, mtu 1480 works for me. However I have a dual-stack eth0 as well IPv6 neighbors with full MTU available, and this setting, even though it's on the "inet6 static" stanza, lowers the MTU for IPv4 too (as though it executed "ip link set eth0 mtu 1480"), if I instead fiddle with "ip -6 route change … mtu 1480" I can get IPv6 a separate MTU for just the default IPv6 gateway. Seems I've run into some buggy behavior and I can't simply add a "post-up ip -6 route change …" to the stanza as this command creates a second default route with a higher metric that's ineffective until I delete the first route. Can anyone clue me in on this behavior? # ip -6 route list 2001:470:e861::/48 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2001:470:e861::1 dev eth0 metric 1 mtu 1500 advmss 1440 hoplimit 4294967295 # ip -6 route change default via 2001:470:e861::1 dev eth0 metric 1 mtu 1480 RTNETLINK answers: File exists # ip -6 route change default via 2001:470:e861::1 dev eth0 mtu 1480 # ip -6 route list 2001:470:e861::/48 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2001:470:e861::1 dev eth0 metric 1 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2001:470:e861::1 dev eth0 metric 1024 mtu 1480 advmss 1420 hoplimit 4294967295 (change = add?) # ip -6 route del default via 2001:470:e861::1 dev eth0 metric 1 # ip -6 route list 2001:470:e861::/48 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295 default via 2001:470:e861::1 dev eth0 metric 1024 mtu 1480 advmss 1420 hoplimit 4294967295 $ wget -S --delete-after --header="Host: security.debian.org" http://schein.debian.org/dists/squeeze/updates/Release … OK! -- Gerald Turner Email: gturner@unzane.com JID: gturner@unzane.com GPG: 0xFA8CD6D5 21D9 B2E8 7FE7 F19E 5F7D 4D0C 3FA0 810F FA8C D6D5
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