From: ken@cs.cornell.edu (Ken Birman)
Subject: Re: Forwarded comments Re: Notes on IP Multicast option for Isis
Organization: Cornell Univ. CS Dept, Ithaca NY 14853
Date: Thu, 24 Dec 1992 17:02:41 GMT

In article <1992Dec24.162926.27546@cs.cornell.edu> ken@cs.cornell.edu (Ken Birman) writes:
>From: gthaker@hannibal.atl.ge.com (Gautam H Thaker)
>
>Here are my two cents worth of comments...
>
>   When will IP mcast be used?
>      - I plan to require that all (or most) machines using Isis support
>	the IP Multicast standard, which was developed by Steve Deering at
>	Stanford and has become part of Solaris 2.1; Steve's code is also
>	available for many other platforms, but perhaps not as a standard
>	offering from the vendor.
>
>Requiring that most machines using isis support IP Multicast seems
>a bit strong. I don't know if HP, DEC, IBM, Lynx etc. support this
>as well as SOlaris 2.1, be cause we worry about using ISIS from all
>these other platforms.

Well, I really prefer to have the standards argument to point to.
based on Werner's comments, sounds like most of this actually do support
the interface, and if Isis does something of its own, we lose the
strong advantage of being "standard compliant".  If, say, Lynx lacks
support for this -- a published IP standard -- why not lean on them
to offer it?  More appealing than porting some wierd Isis solution to
a zillion driver-level interfaces...
>
>      - You will need to have an authorization for "ipmcast" in your isis.rc
>	file.
>Eventually, multicast should be folded in with price of standard ISIS
>to keep ordering process simple, but no big deal here.

Anyone who has Isis-All gets this as part of the package.

>      - Only messages sent in diffusion mode (to the full set of members and
>	clients) will be multicast.  However, you can overlap groups and in this
>	way can build up other patterns pretty easily.
>Not sure about this. Does this mean that if I have peer group of 10 members
>and I do a normal cbcast multicast won't get used? 

Actually, what it really wants is that "the destination includes all members
and all clients".  So, for your case, it would be used.  You don't need
to specify "D" (diffusion mode) explicitly, but you do need the right
destinations...

>Please consider publishing a "performace brief" for ISIS, including
>numbers for multicast perf. I realize that you and your staff does not
>have infinite time, but perhaps slowly something can be built up.

Actually, we had been holding off mostly because of this multicast issue.
I didn't want to compare Isis with things like Ameoba if there would
be some glaring unfairness, like them using hardware multicast and us
using point-to-point communication... now that there is a standard I
can at least quote comparable numbers (and, I am confident, the numbers
will be in the same ballpark as any others, or better -- because if they
aren't, we'll tune until they are!) (That is, for stuff running over UNIX).

>Also, how do people find Solaris 2.x overall?   Do things work seamlessly,
>or is some amount of effort needed to move to Solaris?

Don't know yet.  Others who read this probably can comment but I only
have worked with Solaris to do the initial Isis port -- that went smoothly,
by the way.  We are waiting for Solaris threads and will start to use
the Solaris system much more in 1993 once we are on the threads package.
-- 
Kenneth P. Birman                              E-mail:  ken@cs.cornell.edu
4105 Upson Hall, Dept. of Computer Science     TEL:     607 255-9199 (office)
Cornell University Ithaca, NY 14853 (USA)      FAX:     607 255-4428
Newsgroups: comp.sys.isis