Subject: [Bier] Homenet, and multicast

From: Tim Chown <[email-masked]>
Date: Thu, 20 Jul 2017 16:49:19 +0000

Here’s the main chunk of homenet multicast text from RFC7368.  

There are other references to multicast through topics such as service discovery, and security & realm borders.

At the chairs’ direction, no specific protocol was named, just as no unicast protocol was named.

Once the new homenet WG chairs are appointed, it would be timely to raise the question of bier, babel and multicast with them.

—

3.5.3.  Multicast Support

   It is desirable that, subject to the capacities of devices on certain
   media types, multicast routing is supported across the homenet,
   including source-specific multicast (SSM) [RFC4607].

   [RFC4291] requires that any boundary of scope 4 or higher (i.e.,
   admin-local or higher) be administratively configured.  Thus, the
   boundary at the homenet-ISP border must be administratively
   configured, though that may be triggered by an administrative
   function such as DHCP PD.  Other multicast forwarding policy borders
   may also exist within the homenet, e.g., to/from a guest subnet,
   whilst the use of certain link media types may also affect where
   specific multicast traffic is forwarded or routed.

   There may be different drivers for multicast to be supported across
   the homenet -- for example,

   o  for homenet-wide service discovery, should a multicast service
      discovery protocol of scope greater than link-local be defined

   o  for multicast-based streaming or file-sharing applications

   Where multicast is routed across a homenet, an appropriate multicast
   routing protocol is required, one that as per the unicast routing
   protocol should be self-configuring.  As hinted above, it must be
   possible to scope or filter multicast traffic to avoid it being
   flooded to network media where devices cannot reasonably support it.

   A homenet may not only use multicast internally, it may also be a
   consumer or provider of external multicast traffic, where the
   homenet's ISP supports such multicast operation.  This may be
   valuable, for example, where live video applications are being
   sourced to/from the homenet.

   The multicast environment should support the ability for applications
   to pick a unique multicast group to use.