[Xorp-users] IGMP report group ...?

[Hervé Léonard]

Thank you very much Pavlin and Bruce for your answers. I took your advices
and tried to go further...

In fact, in my first configuration, i did not have the mfea statement (see
my first mail):

	plumbing mfea4 interface eth0 vif eth0...

but only the IGMP configuration statement:

	protocols igmp interface eth0 vif eth0


But the flag ALLMULTI is set on the interface by the option MRT_ADD_VIF
using setsockopt() passed to the kernel.
And setsockopt(MRT_ADD_VIF) is done in mfea_mrouter.cc

is that correct?

Anyway, IGMP version 2 WITHOUT the mfea configuration statement for eth0 it
doesn't work but WITH the mfea configuration, it does:  the IGMP group
appears in xorp.


Thanks,
Leonard


-----Message d'origine-----
De : Pavlin Radoslavov
Envoyé : mardi 7 octobre 2008 19:01
À : Hervé Léonard
Cc : xorp-users at xorp.org
Objet : Re: [Xorp-users] IGMP report group ...?


Hervé Léonard <lherve at interfaceconcept.com> wrote:

>
> Hi,
>
> In fact, i do some other tests...
>
> The flag 'ALLMULTI' for the network card driver (in ifconfig) was not the
> root cause of the group membership in xorp router.
>
> It was in fact the IGMP version number for the interface in Xorp
> configuration.
>
> With the IGMP version 2 (by default) the IGMP membership doesn't work. But
> with version 3, it does.
>
> I thought that only one router on the LAN can send IGMP Query, it is the
> Querier IGMP. And this Querier IGMP should deal with 3 versions of IGMP
for
> all different kinds of hosts on the LAN...
>
> Is that the case with Xorp?

Few things:

* Yes, only the elected Querier should send IGMP Query messages.
* If the Querier is configured for IGMPv3, it should deal with all
  IGMP control messages from other routers and hosts: IGMPv1,
  IGMPv2, IGMPv3.
  The XORP IGMPv3 router-side implementation supports that.
* If the Querier is configured for IGMPv2, the IGMPv3 hosts MUST
  operate in IGMPv2 compatibility mode. If they don't, then you need
  to find the root cause for that: is it on the host side (e.g., the
  host IGMP implementation) or are there some other factors (e.g.,
  firewall entries on either the host or the router side as I
  mentioned in my earlier email on the subject).
* Setting the XORP IGMP version to 3 is a perfectly acceptable
  solution. In the future IGMPv3 and MLDv2 will become the default
  configuration for XORP.

Pavlin

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