Re: Use of SAP in a PIM SSM Network

[Jon Crowcroft <J.Crowcroft@cs.ucl.ac.uk>]

ha ha ha

finally people realize

ssm entails _exactly_ as many problems as simple multicast in terms of
1/ deploying it in routers
2/ changing all the applications to use igmpv3
3/ chaing host OS to use igmpv3
4/ changing session management/annoucement mechanisms

:-)
(no i dont want to revisit SM - ssm is just fine, and ipv6 with some
simple kinks will do many-source multicast just fine too)

so no, we dont have resources to do this, but we are happy to roll in
SSM/igmpv3 changes to the mbone apps if people contrib. them (spritn
have kindly offered to do some apps) - sdr is a non trivial one in
that it needs completely re-writing which is outside the scope of a
university research department's normal activities....

In message <3A1265F8.2276000A@alcatel.be>, Dirk Ooms typed:

 >>
 >>
 >>Jon Crowcroft wrote:
 >>> 
 >>> In message <200011142316.PAA29744@cisco.com>, Toerless Eckert typed:
 >>> 
 >>>  >>> I am trying to understand in a pure SSM network without any shared tree,
 >>>  >>> how would SAP operate? My understanding is that SAP is transmitting on a
 >>>  >>> shared tree. Does it mean that we always stuck with a PIM-SM shared
 >>>  >>> tree, even in a pure SSM network?
 >>> 
 >>>  >>I think you have a network without a shared tree and without SAP. You can
 >>>  >>of course use SSM to get SAP information, but the receivers need to know
 >>>  >>the address of the sources in the first place, which is a bit beyond the
 >>>  >>point of what SAP was meant for in the first place. SAP is nice to have
 >>>  >>in limited environments, but simply trying to broadcast directory information
 >>>  >>on a world-wide scale is not a scaling solution. Already today lots of
 >>>  >>SDP sessions are just made available via the web instead of SAP.
 >>> 
 >>> Toerless
 >>> 
 >>> either you have a well known ssm mcast addr per sap server 
 >>
 >>but the 'sap listener' application requires some changes, it has to join
 >>a specific sap server (which again needs to be listed on a webpage?). 
 >>anyone working on sdr for ssm-only networks?
 >>
 >>dirk

 cheers

   jon