All things related to multicast

[Jay Ford <>]

On Tue, 12 Nov 2002, Peter John Hill wrote:
> On a separate note, (which you can respond off-list if you wish) are
> you considering going to a layer 3 core. I am pretty interested in
> moving some of our Tier-2 groups, as we call them, off of the l2 core,
> and routing them. Basically, any router that we do not control. Our CS
> department, for example, connects their router to our cores, and when
> we want to make changes to our ospf, for example, we need to coordinate
> with them, and a couple of other groups.

I've built a L3 core here at the University of Iowa, with good results.  I
admittedly have a flatter net than most, because we've been successful in
getting central authority for networking as a campus infrastructure.  I only
have to deal with 2 routers which aren't mine, which I do statically (no
OSPF, BGP, etc.) to minimize complexity & disruption potential.  Also, a few
years ago I opted for a smaller number of larger routers to replace the
larger number of smaller routers I used to have.  This enable things like
full mesh connectivity which are difficult with larger numbers of boxes.

My net is:
   o  4 core routers (each a Catalyst 6500+MSFC)
   o  2 border routers (each a 7513)
   o  core routers connected to each other via a full mesh of point-to-point
      GigEther links (IP /30 subnets)
   o  core routers each connected to each border router via point-to-point
      FastEther links (IP /30 subnets), to be upgraded to GigEther as soon as
      I replace the 7513s with something newer
   o  OSPF running on the core & border routers, for just our campus nets
   o  iBGP between the border routers, unicast & multicast
   o  iBGP unicast one-way from each border router to each core router, to
      convey a conditionally originated default & other routes which preempt
      the default
   o  PIM-SM enabled on all core-core & core-border links
   o  each border router configured to be an RP via anycast, with mesh-group
      MSDP in between the border routers
   o  each core router statically configured with the anycast RP address,
      meaning I don't need auto-RP, BSR, etc.
   o  static mroute default defined on each core router pointing at the RP
      address
   o  IGMP snooping enabled on all capable boxes, including the core
      6500+MSFC boxes
   o  CGMP enabled on all router interfaces, for use by switches which don't
      do IGMP snooping

There is also a dorm net router, which is just like the core routers but not
fully meshed.

This has worked well, with none of the recently discussed problems associated
with a L2 core.  If you can get it to work in your (administrative,
organizational, political) environment, I highly recommend it.

> Does anyone know of any Network Engineering/Architecture mailing lists
> of a more general nature for I2 schools?

That'd be useful.

________________________________________________________________________
Jay Ford, Network Engineering Group, Information Technology Services
University of Iowa, Iowa City, IA 52242
email: 
,
 phone: 319-335-5555, fax: 319-335-2951