[Twisted-Python] RFC: IPv6 multicast join/ticket 6597
Jason Litzinger
jlitzingerdev at gmail.com
Sat Aug 6 15:46:46 MDT 2016
An update for those interested. I've been hoping for a solution to
test IPv6 multicast using only the loopback interface. Unfortunately,
the only working (on Linux) solution I've found is to manually add a
route for the multicast prefix used in the tests.
E.g. ip -6 route add ff01::/16 dev lo
Without this, and assuming I specify the loopback interface index, a
"Network Unreachable" error results. I'm fairly certain the culprit
is a kernel route:
unreachable default dev lo table unspec proto kernel metric
4294967295 error -101 pref medium
local ::1 dev lo table local proto none metric 0 pref medium
unreachable default dev lo table unspec proto kernel metric
4294967295 error -101 pref medium
That's the default output of `ip -6 route show table all` on my
machine (Ubuntu 16.04). I haven't found much information on why that
route exists (let alone twice), so I'm going to have to turn to the
kernel source.
Regardless, route manipulation for tests is a non-starter, so unless
there's a way to flag the tests as requiring a network interface,
it'll be a while before I submit patches on the original feature.
Thanks for all the suggestions/feedback and I welcome any more.
-Jason
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