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

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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 <[email protected]> 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
> [email protected]
> https://www.ietf.org/mailman/listinfo/magma
>

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<div>Hi Kiyoaki Kawaguchi,</div>
<div>=A0</div>
<div>=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 Yes, I think=A0it should be split up=A0like IS_IN =
report and all the split up=A0packets should follow 7.6.3.2 of rfc 3810. I =
have never handled this in code though</div>
<div>=A0</div>
<div>Thanks,</div>
<div>Indranil<br><br></div>
<div class=3D"gmail_quote">On Tue, Sep 28, 2010 at 1:08 PM, K.Kawaguchi <sp=
an dir=3D"ltr">&lt;<a href=3D"mailto:[email protected]">kawaguti@ysknet=
.co.jp</a>&gt;</span> wrote:<br>
<blockquote style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex=
; PADDING-LEFT: 1ex" class=3D"gmail_quote">Hi all,<br><br># Only the subjec=
t was changed.<br><br>I have another question.<br><br>About a size limit of=
 a Multicast Address Specific Query in MLDv2.<br>
<br>How is a query transmitted when the number of multicast source<br>addre=
sses of a query message is limited by the MTU?<br><br>Is a Query split like=
 a Report type IS_IN?<br>(It isn&#39;t a Query like Report type IS_EX, is i=
t?)<br>
<br><br>RFC3810<br>--------------------------------------------------------=
----------------<br>5. =A0Message Formats<br><br>5.1. =A0Multicast Listener=
 Query Message<br><br>5.1.10. =A0Number of Sources (N)<br><br>=A0 The Numbe=
r of Sources (N) field specifies how many source addresses<br>
=A0 are present in the Query. =A0This number is zero in a General Query or<=
br>=A0 a Multicast Address Specific Query, and non-zero in a Multicast<br>=
=A0 Address and Source Specific Query. =A0This number is limited by the MTU=
<br>=A0 of the link over which the Query is transmitted. =A0For example, on=
 an<br>
=A0 Ethernet link with an MTU of 1500 octets, the IPv6 header (40 octets)<b=
r>=A0 together with the Hop-By-Hop Extension Header (8 octets) that<br>=A0 =
includes the Router Alert option consume 48 octets; the MLD fields up<br>=
=A0 to the Number of Sources (N) field consume 28 octets; thus, there are<b=
r>
=A0 1424 octets left for source addresses, which limits the number of<br>=
=A0 source addresses to 89 (1424/16).<br><br><br>5.2. =A0Version 2 Multicas=
t Listener Report Message<br><br>5.2.15. =A0Multicast Listener Report Size<=
br><br>
=A0 If the set of Multicast Address Records required in a Report does not<b=
r>=A0 fit within the size limit of a single Report message (as determined<b=
r>=A0 by the MTU of the link on which it will be sent), the Multicast<br>=
=A0 Address Records are sent in as many Report messages as needed to<br>
=A0 report the entire set.<br><br>=A0 If a single Multicast Address Record =
contains so many source<br>=A0 addresses that it does not fit within the si=
ze limit of a single<br>=A0 Report message, then:<br><br>=A0 o =A0if its Ty=
pe is not IS_EX or TO_EX, it is split into multiple<br>
=A0 =A0 =A0Multicast Address Records; each such record contains a different=
<br>=A0 =A0 =A0subset of the source addresses, and is sent in a separate Re=
port.<br><br>=A0 o =A0if its Type is IS_EX or TO_EX, a single Multicast Add=
ress Record<br>
=A0 =A0 =A0is sent, with as many source addresses as can fit; the remaining=
<br>=A0 =A0 =A0source addresses are not reported. =A0Although the choice of=
 which<br>=A0 =A0 =A0sources to report is arbitrary, it is preferable to re=
port the<br>=A0 =A0 =A0same set of sources in each subsequent report, rathe=
r than<br>
=A0 =A0 =A0reporting different sources each time.<br><br>Best Regards<br><f=
ont color=3D"#888888">--<br>Kiyoaki Kawaguchi<br><br>______________________=
_________________________<br>magma mailing list<br><a href=3D"mailto:magma@=
ietf.org">[email protected]</a><br>
<a href=3D"https://www.ietf.org/mailman/listinfo/magma" target=3D"_blank">h=
ttps://www.ietf.org/mailman/listinfo/magma</a><br></font></blockquote></div=
><br>

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