Subject: Mixed Static and Dynamic Routing

From: "Freedman, Jerome" <[email-masked]>
Date: Thu, 20 Feb 1997 08:20:31 -0500

Please excuse me if this is a dumb question. I have to ask it and this
seems to be the place.

Suppose I have a network situation such as this

                     |
    Multi-cast ------|------Multicast 
     router          |       router

   The link between the routers is a direct link so there need be no
tunneling. I have the further restriction that all that can go across
the link are data packets, no routing protocol packets may traverse the
link. Arbitrary routing protocols, (MOSPF etc) may run on either side
but they may not communicate, the routing on the link is static. Can I
get this configuration to work? Can multi-cast trees be built with these
constraints

   Again, excuse any ignorance displayed here. I have no direct
experience with multi-casting, multi-cast routers etc and please, these
requirements are not mine so I need no flames about the merits of the
configuration.

                           Jerry Freedman,Jr

---

From: Dino Farinacci <[email-masked]>
Date: Thu, 20 Feb 1997 09:49:07 -0800

>> get this configuration to work? Can multi-cast trees be built with these

    Yes, but you'd have to use a mix of static routes and jury-rig your
    IGMP to report all groups each router has cached.

    Can you say why control packets cannot flow. At a mimimum, if you could
    get DVMRP probes or PIM query messages to flow over the subnet, you could
    have a dense-mode tree built dynamically. But then you lose all pruning
    capabilities.

    It would be interesting to know what your application for this requirement
    is.

Dino

---

From: Bill Fenner <[email-masked]>
Date: Thu, 20 Feb 1997 12:25:18 PST

>    IGMP to report all groups each router has cached.

Assuming that the routers can know about group membership, meaning that
you're running PIM-SM.

If the topology is static, it would be possible to configure static
routes to make this work, although the routers would also have to
be statically configured to know that there is a neighbor present
since they can't exchange control messages.  And if control messages
aren't allowed, pruning won't work, which is seriously discouraged
if you are going to connect to the MBone.

  Bill