Re: [magma] A size limit of a Multicast Address Specific Query in MLDv2

"K.Kawaguchi" <kawaguti@ysknet.co.jp> Thu, 30 September 2010 05:50 UTC

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Subject: Re: [magma] A size limit of a Multicast Address Specific Query in MLDv2
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Hi Indranil-san,

Thank you for your answer.

>                                 Yes, I think it should be split up like
> IS_IN report and all the split up packets should follow 7.6.3.2 of rfc 3810.

I agree of processing of following 7.6.3.2.


Best Regards
--
Kiyoaki Kawaguchi



"Indranil Bhattacharya <myselfindranil@gmail.com>" wrote:

> 
> Hi Kiyoaki Kawaguchi,
> 
>                                 Yes, I think it should be split up like
> IS_IN report and all the split up packets should follow 7.6.3.2 of rfc 3810.
> I have never handled this in code though
> 
> Thanks,
> Indranil
> 
> On Tue, Sep 28, 2010 at 1:08 PM, K.Kawaguchi <kawaguti@ysknet.co.jp> wrote:
> 
> > Hi all,
> >
> > # Only the subject was changed.
> >
> > I have another question.
> >
> > About a size limit of a Multicast Address Specific Query in MLDv2.
> >
> > How is a query transmitted when the number of multicast source
> > addresses of a query message is limited by the MTU?
> >
> > Is a Query split like a Report type IS_IN?
> > (It isn't a Query like Report type IS_EX, is it?)
> >
> >
> > RFC3810
> > ------------------------------------------------------------------------
> > 5.  Message Formats
> >
> > 5.1.  Multicast Listener Query Message
> >
> > 5.1.10.  Number of Sources (N)
> >
> >   The Number of Sources (N) field specifies how many source addresses
> >   are present in the Query.  This number is zero in a General Query or
> >   a Multicast Address Specific Query, and non-zero in a Multicast
> >   Address and Source Specific Query.  This number is limited by the MTU
> >   of the link over which the Query is transmitted.  For example, on an
> >   Ethernet link with an MTU of 1500 octets, the IPv6 header (40 octets)
> >   together with the Hop-By-Hop Extension Header (8 octets) that
> >   includes the Router Alert option consume 48 octets; the MLD fields up
> >   to the Number of Sources (N) field consume 28 octets; thus, there are
> >   1424 octets left for source addresses, which limits the number of
> >   source addresses to 89 (1424/16).
> >
> >
> > 5.2.  Version 2 Multicast Listener Report Message
> >
> > 5.2.15.  Multicast Listener Report Size
> >
> >   If the set of Multicast Address Records required in a Report does not
> >   fit within the size limit of a single Report message (as determined
> >   by the MTU of the link on which it will be sent), the Multicast
> >   Address Records are sent in as many Report messages as needed to
> >   report the entire set.
> >
> >   If a single Multicast Address Record contains so many source
> >   addresses that it does not fit within the size limit of a single
> >   Report message, then:
> >
> >   o  if its Type is not IS_EX or TO_EX, it is split into multiple
> >      Multicast Address Records; each such record contains a different
> >      subset of the source addresses, and is sent in a separate Report.
> >
> >   o  if its Type is IS_EX or TO_EX, a single Multicast Address Record
> >      is sent, with as many source addresses as can fit; the remaining
> >      source addresses are not reported.  Although the choice of which
> >      sources to report is arbitrary, it is preferable to report the
> >      same set of sources in each subsequent report, rather than
> >      reporting different sources each time.
> >
> > Best Regards
> > --
> > Kiyoaki Kawaguchi
> >
> > _______________________________________________
> > magma mailing list
> > magma@ietf.org
> > https://www.ietf.org/mailman/listinfo/magma
> >
> 
> 
> 
> 
>