(usagi-users 02730) Re: Multicast IPv6 over (proto-41/sit) tunnels

[Pekka Savola <pekkas@xxxxxxxxxx>]

On Sun, 4 Jan 2004, Jeroen Massar wrote:
> Is this because of the POINTTOPOINT flag? Or is there other code
> preventing multicast packets and thus to be silently dropped?
> ip6tables is empty btw.

For what it's worth, I've both received and sent v6 multicast over 
tunnels.  It works, at least, with Red Hat's 2.4.20-20.7 -kernel.  I 
haven't tested it with vanilla kernels or USAGI patch.. so something 
might, of course, have changed in the meantime..

(The tricky part with tunnels is that multicast apps like vic and sdr 
don't use them by default, but rather pick the lowest-numbered 
non-loopback device -- and you have to specify the device explicitly 
with '-x <interface-index>' -parameter.  But as you are sending the 
traffic based on tcpdump, this should not be a problem in this case.)

My configs are below, just in case it might help..

[root@noctv root]# ip -6 l l
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: sit0@NONE: <NOARP> mtu 1480 qdisc noop 
    link/sit 0.0.0.0 brd 0.0.0.0
3: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    link/ether 00:e0:29:0b:da:0c brd ff:ff:ff:ff:ff:ff
4: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    link/ether 00:00:c0:69:ef:e9 brd ff:ff:ff:ff:ff:ff
5: sit1@NONE: <POINTOPOINT,NOARP,UP> mtu 1480 qdisc noqueue 
    link/sit 0.0.0.0 peer 193.166.3.140

[root@noctv root]# ip -6 a l
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue 
    inet6 ::1/128 scope host 
3: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    inet6 fe80::2e0:29ff:fe0b:da0c/64 scope link 
4: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
    inet6 fe80::200:c0ff:fe69:efe9/64 scope link 
5: sit1@NONE: <POINTOPOINT,NOARP,UP> mtu 1480 qdisc noqueue 
    inet6 2001:708:10:32::2/64 scope global 
    inet6 fe80::c1a6:422/64 scope link 
    inet6 fe80::a00:436/64 scope link 

[root@noctv root]# ip -6 r l
unreachable ::/96 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable ::ffff:0.0.0.0/96 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
2001:708:10:32::/64 via :: dev sit1  proto kernel  metric 256  mtu 1480 advmss 1420
unreachable 2002:a00::/24 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable 2002:7f00::/24 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable 2002:a9fe::/32 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable 2002:ac10::/28 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable 2002:c0a8::/32 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable 2002:e000::/19 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
unreachable 3ffe:ffff::/32 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
2000::/3 via 2001:708:10:32::1 dev sit1  metric 1  mtu 1480 advmss 1420
fe80::/64 dev eth1  proto kernel  metric 256  mtu 1500 advmss 1440
fe80::/64 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
fe80::/64 via :: dev sit1  proto kernel  metric 256  mtu 1480 advmss 1420
ff00::/8 dev eth1  proto kernel  metric 256  mtu 1500 advmss 1440
ff00::/8 dev eth0  proto kernel  metric 256  mtu 1500 advmss 1440
ff00::/8 dev sit1  proto kernel  metric 256  mtu 1480 advmss 1420
unreachable default dev lo  proto none  metric -1  error -101

[root@noctv root]# ip -6 t l
sit0: ipv6/ip  remote any  local any  ttl 64  nopmtudisc
sit1: ipv6/ip  remote 193.166.3.140  local any  ttl 64 
[root@noctv root]#

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings