Subject: Re: stockholm.mbone

From: Peter Lothberg <[email-masked]>
Date: Tue, 23 Sep 97 3:20:34 MET DST

>  > I'm expecting most exchangepoints to have a separate media to support
>  > multicast, and then we need a EGP that allow us to do policy in a 
>  > more reliable and flexible way than leaking stuff into DVMRP.
>  >
> I'm expecting most exchange points to run multicast native on the same
> media they run unicast when real switches are deployed.

It's very unlikely that your Mulicast topology will match your Unicast
topology, even if they are on the same media. 

Then look at a scenario with multiple exchange points, your really
want to be able to specify the policies different.

>  > DVMRP at the exchange is used to get the correct next_hop for
>  > RPF-checks, as the unicast traffic traverses the unicast part of the
>  > exchange point.
>  > 
> Having to run two routing protocols is exactly the problem with the
> dual-media approach which seem to be mandated by broken equipment
> rather than network design.

If everyone was singlehomed, and the internet looked like one 
single tree from the root in my bathroom, yes, but I don't think that
will be the case in reality.

You end up with a EGP that is multiprotocol instead of the 'ships in
the night' approach, but that's about it, the functionality will be
the same.

-Peter

---

From: Petri Helenius <[email-masked]>
Date: Tue, 23 Sep 1997 09:34:23 +0300 (EEST)

> topology, even if they are on the same media. 

Yes, but this is not a reason to have another media.
 > want to be able to specify the policies different.
Yes, but this is not solved by having another media.

 > will be the case in reality.

Not running two routing protocols does not make you single-homed. It
just makes the assumption of your unicast and multicast topologies and
policies to be the same. Completely different.
 > the night' approach, but that's about it, the functionality will be

I think we both know what can be done with the currently available
pieces of software and it's definetly less than what should be doable.

However, how does one join this D-GIX multicast FDDI?

Pete

---

From: Jeremy Porter <[email-masked]>
Date: Tue, 23 Sep 1997 09:15:35 -0500

>the night' approach, but that's about it, the functionality will be

That might be the best solution, but I haven't seen any work
on a protocol that could handle it.  For a multihomed site,
or a backbone it doesn't seem possible to setup "peering" multicast
links, or to provide path fallover, or to load balance base on
shortest path.  Perhaps PIM would handle these, but the
admistrative scoping of stuff in DVMRP seems unwieldy, and
the apparent lack of real metrics in the presense of tunnels, etc
seems to be a problem.  If BGP could be extended that would be
one thing, but BGP has enough problems, and lacks real
metrics also.

---
Jeremy Porter, Freeside Communications, Inc.      [email-masked]
PO BOX 80315 Austin, Tx 78708  |  1-800-968-8750  |  512-458-9810
http://www.fc.net

---

From: Petri Helenius <[email-masked]>
Date: Tue, 23 Sep 1997 18:05:40 +0300 (EEST)

> one thing, but BGP has enough problems, and lacks real
So you are saying that BGMP does not solve this problem?

What's wrong with that?

Pete

---

From: Petri Helenius <[email-masked]>
Date: Tue, 23 Sep 1997 20:59:16 +0300 (EEST)

Jeremy Porter writes:
 > 
 > I'm at a lose, I haven't seen the work on BGMP to know one way or
 > the other, but that still involves running two protocols, which 
 > is what another poster was commenting on.  Currently there do not

Not really, you have to read the drafts, othervise we'll waste a lot
of bandwidth unneccessarily.

 > seem to be any freely available implementations of multicast routing
 > protocols, other than DVMRP.  So, a number of applications
 > I would like to be able to impelement including localized highbandwidth
 > applications, don't have the admistrative boundry scoping features,
 > metrics, etc, that do what I need.
 > 
Ok, so you need your problems solved and somebody should do it for
free? Then I suggest you take a look at pimd or gated's PIM
impementations, if they don't satisfy your requirements, then you
either have to actually shell out money to get a commercial
implementation or live with the limitations of the freely available
ones.

Pete

lications
I would like to be able to impelement including localized highbandwidth
applications, don't have the admistrative boundry scoping features,
metrics, etc, that do what I need.

---