Re: [magma] Comments draft-ietf-magma-snoop-11.txt (SSM)

[Pekka Savola <[e-mail]>]

On Mon, 17 May 2004, Isidor Kouvelas wrote:
> Excuse me but were you hybernating during the last call etc for this
> draft? This is currently in the RFC editor queue!

Further, I think there was considerable pushback for configured SSM 
ranges in IETF59 when we had this debate.

If folks think that's important, it should be easily to specify as a 
separate draft to the new mrdisc.  Then we'd see who would bother 
implementing it :)

> Toerless Eckert writes:
> >I would hereby like to express my opinion that subject draft MUST
> >mentioned SSM explicitly (and provide appropriate detail) before
> >progressing any further. Without mentioning ASM and SSM service model support
> >explicitly, we will solely get yet another document that will not
> >support SSM sufficiently anmore and given that SSM is recognized by
> >mboned to be the one service model the IETF should focus further
> >work on, it is unacceptable to over and over get the excuse of
> >"oh well, the SSM support side can be done later in a different document".
> >
> >[ Cc'ed ssm and mboned working groups to alert them about this lack
> >  of right focus of that draft. Please keep replies to the 
> >  Reply-To: [e-mail], to avoid flooding three mailing lists with this. ]
> >
> >Specifically this is what i think is needed:
> >
> >  SSM can be used in varying IPv4 address ranges, a decision as to limit
> >  it to specific address ranges (like only the default 232.0.0.0/8 ) has
> >  not been made (i would also oppose that). IGMP snooping switches on
> >  the other hand should be zero-config simply deployable devices that
> >  do not necessarily need to be configured to know L3 specifics like
> >  an SSM range.
> >
> >  For this reason i would recommend that a default mode of operations
> >  of IGMPv3 switches is mandated which provides for SM-safe-reporting, 
> >  meaning that receiver systems expecting to use SSM will not be impacted by
> >  (erroneous) receiver systems using ASM style membership reports on
> >  any addresses.
> >
> >  Problem:
> >    Reporter 1 on port 1 sending an INCLUDE({S},G) IGMPv3 report, reporter
> >    2 on port 2 sending an EXCLUDE({},G) IGMPv3 report. IGMP snooping
> >    switch builds aggregate state for G to report to upstream router(s).
> >    This aggregate state is (according to IGMPv3 specs) EXCLUDE({},G).
> >    If only this is reported, reporter 1 SSM application will fail because
> >    the router never receives any INCLUDE({S},G) reports.
> >  
> >  Solution:
> >    Define SSM-safe-reporting to be a condition for an IGMP snooping switch
> >    in which it ensures that all include({S},G) membership state will
> >    be reported correctly to router ports irrespective of exclude({..},G)
> >    reports.
> >
> >    There are lots of alternatives on how a switch can do this, the
> >    most simple one is to pass on _all_ membership reports from
> >    hosts without suppressing any of them on ports connected to routers.
> >    That way in above example both the INCLUDE and EXCLUDE mode report
> >    would be seen by the router and if G is SSM, the router can correctly
> >    ignore the EXCLUDE mode report. 
> >
> >    There are alternatives on how to do SSM-safe-reporting which are
> >    more complex but provide more membership report suppression/aggregation
> >    towards router ports, but i think details of those should be left
> >    up for individual implementations.
> >    
> >    I would simply mandate that the default operations of an IGMP snooping
> >    switch must provide for SSM-safe-reporting without explicit manual
> >    configuration of the SSM range and without expecting SSM to be only
> >    operated on a well known SSM-range (IPv4).
> >
> >  Obviously, this is only a problem for IPv4, as in IPv6 the SSM-range
> >  is well defined, MLD-snooping routers can thus rely on that
> >  range definition.
> >
> >  And yes, i understand that this is only an informational document, but
> >  that's all we have. Hugh also does not mentiones snooping in
> >  draft-holbrook-idmr-igmpv3-ssm-06.txt.
> >
> >Thanks
> >	Toerless
> >
> >_______________________________________________
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> >[e-mail]
> >https://www1.ietf.org/mailman/listinfo/magma
> >
> 
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-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings


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