Re: MBone

[Joe Touch <touch at ISI.EDU>]

Kevin C. Almeroth wrote:
> > > Multicast is necessarily a LOT weaker:
> > >
> > >     1) I can get a copy of packets by normal operation
> > >     (join a group). there is no equivalent for UDP,
> > >     notably for paths that aren't shared.
>
> Again, not in all cases.  You over-simplify the effectiveness of scoping.

Unicast has TTLs too.

> You can't have it both ways.  Yes, there is a situation where you can obtain
> a copy of a multicast packet through standard operation.  But the fact
> that scoping and addressing make it non-trivial

Agreed - scoping sets some boundaries, but it's primitive as a
'security' mechanism, because everyone within those boundaries can very
easily get a backet.

The same is just not nearly as true for unicast.

> > >     2) UDP has application, network, and tunnel encryption that
> > >     is both widely deployed and widely used. there is
> > >     no equivalent for multicast.
>
> I disagree...  a number of commercial multicast apps have encryption.

Agreed. What I am asserting (by the above) is that security is clearly
important to the average user, and that the average user won't accept
obfuscation as a solution.

Joe