[Xorp-users] Fwd: Fwd: Problem in IPv6 SSM Multicast

[Pavlin Radoslavov]

> > > > show mld group
> > >
> > >
> > > Interface    Group           Source          LastReported Timeout V
> > State
> > > sk0          ff02::2         ::              fe80::219:5bff:fe85:cfc7
> > > 243 1     E
> > > sk0          ff02::d         ::              fe80::219:5bff:fe85:cfc7
> > > 243 1     E
> > > sk0          ff02::16        ::              fe80::219:5bff:fe85:cfc7
> > > 243 1     E
> > > sk0          ff02::1:ff00:1  ::              fe80::219:5bff:fe85:cfc7
> > > 243 1     E
> > > sk0          ff02::1:ff2f:1468 ::              fe80::219:5bff:fe2f:1468
> > > 248 2     E
> > > sk0          ff02::1:ff85:cfc7 ::              fe80::219:5bff:fe85:cfc7
> > > 243 1     E
> > > sk0          ff02::2:15ba:6cf7 ::              fe80::219:5bff:fe85:cfc7
> > > 243 1     E
> >
> > It doesn't seem that the client/receiver with IPv6 address
> > 2001:ec2:4002:fa11:200:24ff:fec4:3235 has joined group ff3e::1234.
> 
> 
> The ipv6 address 2001:ec2:4002:fa11:200:24ff
> >
> > :fec4:3235 is the address of the streaming server. :)
> >
> 
> > So your guess in your original email is correct: there is something
> > wrong with the receiver so it hasn't joined the multicast group.
> > Could you run tcpdump to capture all ICMPv6 (incl. MLD) traffic and
> > confirm that XORP is sending the periodic query messages, but the
> > receiver itself never sends MLDv2 Join messages.
> 
> 
> Here are the logs from tcpdump taken on the LAN side of the router (router
> ----- receiver)
> 20:24:32.872230 IP6 (hlim 1, next-header: Options (0), length: 36)
> fe80::219:5bff:fe85:cfc7 > ip6-allnodes: HBH (rtalert: 0x0000) (padn)[icmp6
> sum ok] ICMP6, multicast listener query, length 28v2  [max resp delay=10000]
> [gaddr :: robustness=2 qqi=125]

OK: the router sends the Query

> 20:24:32.876596 IP6 (hlim 1, next-header: Options (0), length: 32)
> fe80::219:5bff:fe85:cfc7 > ff02::16: HBH (padn)(rtalert: 0x0000) [icmp6 sum
> ok] ICMP6, multicast listener report, length 24max resp delay: 0 addr:
> ff02::16

OK: MLDv1 Report from the router itself that it is a member of group
ff02::16

> 20:24:32.892588 IP6 (hlim 1, next-header: Options (0), length: 32)
> fe80::219:5bff:fe85:cfc7 > ip6-allrouters: HBH (padn)(rtalert: 0x0000)
> [icmp6 sum ok] ICMP6, multicast listener report, length 24max resp delay: 0
> addr: ip6-allrouters

OK: MLDv1 Report from the router itself that it is a member of group
ip6-allrouters

> 20:24:32.906594 IP6 (hlim 1, next-header: Options (0), length: 32)
> fe80::219:5bff:fe85:cfc7 > ff02::d: HBH (padn)(rtalert: 0x0000) [icmp6 sum
> ok] ICMP6, multicast listener report, length 24max resp delay: 0 addr:
> ff02::d

OK: MLDv1 Report from the router itself that it is a member of group
ff02::d

> 20:24:32.906613 IP6 (hlim 1, next-header: Options (0), length: 32)
> fe80::219:5bff:fe85:cfc7 > ff02::1:ff00:1: HBH (padn)(rtalert: 0x0000)
> [icmp6 sum ok] ICMP6, multicast listener report, length 24max resp delay: 0
> addr: ff02::1:ff00:1

OK: MLDv1 Report from the router itself that it is a member of group
ff02::1:ff00:1

> 20:24:32.906634 IP6 (hlim 1, next-header: Options (0), length: 32)
> fe80::219:5bff:fe85:cfc7 > ff02::2:15ba:6cf7: HBH (padn)(rtalert: 0x0000)
> [icmp6 sum ok] ICMP6, multicast listener report, length 24max resp delay: 0
> addr: ff02::2:15ba:6cf7

OK: MLDv1 Report from the router itself that it is a member of group
ff02::2:15ba:6cf7

> 20:24:32.910605 IP6 (hlim 1, next-header: Options (0), length: 32)
> fe80::219:5bff:fe85:cfc7 > ff02::1:ff85:cfc7: HBH (padn)(rtalert: 0x0000)
> [icmp6 sum ok] ICMP6, multicast listener report, length 24max resp delay: 0
> addr: ff02::1:ff85:cfc7

OK: MLDv1 Report from the router itself that it is a member of group
ff02::1:ff85:cfc7

> 20:24:37.389295 IP6 (hlim 1, next-header: Options (0), length: 36)
> fe80::219:5bff:fe2f:1468 > ff02::16: HBH (rtalert: 0x0000) (padn)[icmp6 sum
> ok] ICMP6, multicast listener report v2, length 28, 1 group record(s) [gaddr
> ff02::1:ff2f:1468 is_ex { }]

OK: MLDv2 Report from the client that it is a member of group
ff02::1:ff2f:1468 for all sources.

It appears that the MLDv2 join mechanism between the client and the
router is working for group ff02::1:ff2f:1468 (which is the group
automatically joined by the kernel on the client's interface).

However, I don't seen any join for the multicast group from the
client's application.

> Back when I was exploring ipv4 ssm, everytime I click either on the play or
> stop button of the vlc client, I always see an IGMP join or prune message.
> Shouldn't  it that it also applies to MLDv2? However, I'm not seeing any
> here.

I am not familiar with vlc, but what you say is the logically
expected behavior.
You might want to contact the vlc author(s) about that.

> > BTW, what about MLDv1 Join messages? If you configure the client to
> > join some (*,G) multicast group does it initiate MLDv1 Join?
> >
> My current setup is intended for PIM-SSM traffic. Can it also apply to PIM
> SM considering the setup consist of only two routers?

Yes, you can, but then you must configure one of the routers as the
RP. For testing purpose you could just try without any
RP. Obviously, multicast routing won't work, but the "show mld
group" output will tell us whether MLDv1 Join works for the
application (and whether the router will record that).

Regards,
Pavlin