Subject: Re: stockholm.mbone

From: Peter Lothberg <[email-masked]>
Date: Mon, 22 Sep 97 0:08:03 MET DST

>  > Or is BGP4+, with multicast, available on our favourite routers?
>  > 
> No, but we could do PIM-DM + DVMRP routing if that would not kill the
> Gigaswitch (I've no idea if it would do that or not)

This is what's currently being done using a separate FDDI;

interface Fddi0/0/0
 ip address 193.10.80.43 255.255.255.240
 no ip redirects
 no ip directed-broadcast
 no ip proxy-arp
 ip pim sparse-mode
 ip dvmrp unicast-routing
 ip route-cache same-interface
 no ip route-cache optimum
 ip route-cache distributed
 no keepalive

And from this box I run PIM-SM.

The Gigaswitch has very little understanding of multicast, it seams to
treat is a broadcast and have it's poor little cpu do do packet
replication. 

If there is lot's of Multicast traffic, and a DM configuration it
kindof defeats the point of having a switch in the first case. -:)

> That would be an interim step before we'll get real solutions from our
> favourite vendors.

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.

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.

-Peter

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From: Mike OBrady <[email-masked]>
Date: Mon, 22 Sep 1997 08:30:43 +0000 (GMT)

> RPF-checks, as the unicast traffic traverses the unicast part of the

Hmm... Why do I only see one neighbour on DGix then?

DGix#mrinfo
194.68.128.49 [version cisco 11.1] [flags: PMS]:
  194.68.128.49 -> 194.68.128.51 (Stockholm-DGIX.kolumbus.net) [1/0/pim]
  194.8.225.138 -> 194.8.225.137 (lhr-s4.london.bactel.net)
[1/0/pim/querier]

And we were just in the process of install a 2Mbs Sat feed for Mbone to
cover europe... (back traffic over landlines). Anyone want to share in?

Rgds
---
Mike O'BradY                                      http://www.on-net.co.uk
Technical Support                                 [email-masked]
ON-NET Internet Service Provider                  Yes we sell to ISPs
Tel: ++44-181-256-9990                            FAX: ++44-181-288-0222

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From: Petri Helenius <[email-masked]>
Date: Mon, 22 Sep 1997 17:02:49 +0300 (EEST)

> Hmm... Why do I only see one neighbour on DGix then?

Because you are one of the two who does not know what "separate" means
or haven't read the rules that prohibit running mcast over DGIX
itself.

Pete

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From: Petri Helenius <[email-masked]>
Date: Mon, 22 Sep 1997 16:58:09 +0300 (EEST)

>  ip address 193.10.80.43 255.255.255.240
The address space looks awfully small for an interconnect point.

 >  ip pim sparse-mode

Also, you shouldn't run PIM-SM over an interconnect since it would
require RP sharing along the participants which is not a good idea.

 > And from this box I run PIM-SM.
I failed to find information how one (who is already on D-GIX)
connects to this separate FDDI. It seems to be more difficult in the
future when D-GIX is de-colocating the equipment. 
 > treat is a broadcast and have it's poor little cpu do do packet
This is fairly common along the less-clueful vendors.

 > kindof defeats the point of having a switch in the first case. -:)
DM nor SM makes no difference in this case. The fact that an average
switch cannot intelligently forward multicast frames is an unfortunate
fact of life.

 > 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.

 > RPF-checks, as the unicast traffic traverses the unicast part of the
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.

Pete