Re: [Roll] [roll] #105: trickle-mcast: how to determine scope of MPL domain

["roll issue tracker" <[e-mail]>]

#105: trickle-mcast: how to determine scope of MPL domain


Comment (by mcr@…):

 From: Robert Cragie <[e-mail]>

 1. A packet with a link-local mc address doesn't need tunnelling and
    doesn't need trickle multicast as it is intended to go only one hop
    and is therefore sent using link-layer broadcast without any MPL
 option.

 2. We have generally used the term "subnet-local" in the case of where
    the MPL domain covers the multi-link subnet exactly. If the
    originator is in the MPL domain, and all the intended recipients are
    in the MPL domain, then any packet forwarded by a MPL forwarder will
 be:
     1. Unencapsulated
     2. Have subnet-local mc address (e.g. FF03-based)
     3. Have a MPL option

 3. There is the other case where if the originator is not in the MPL
    domain or at least one of the intended recipients is not in the MPL
    domain (scope rules), then any packet forwarded by a MPL forwarder
    will be:
     1. Encapsulated
     2. Outer header will have subnet-local mc address (e.g.
        FF03-based). This can be used to control propagation in
        conjunction with the MPL option.
     3. Outer header will have a MPL option
     4. Inner header will have site local mc address (e.g. FF05-based).
        This will be tunnelled to multicast exit points
     5. Inner header will not have a MPL option

 4. The alternative to (3) is to use link-local mc address in
    conjunction with a MPL option:
     1. Encapsulated
     2. Outer header will have link-local mc address (e.g. FF02-based).
        This cannot be used to control propagation as it only goes one
        hop; the MPL option is used alone
     3. Outer header will have a MPL option
     4. Inner header will have site local mc address (e.g. FF05-based).
        This will not be tunnelled as it is recapsulated every hop
     5. Inner header will not have a MPL option

-- 
----------------------------+----------------------------------------------
 Reporter:  mcr@…           |       Owner:  draft-ietf-roll-trickle-mcast@…
     Type:  defect          |      Status:  new
 Priority:  major           |   Milestone:
Component:  trickle-mcast   |     Version:
 Severity:  In WG Last      |  Resolution:
  Call                      |
 Keywords:                  |
----------------------------+----------------------------------------------

Ticket URL: <https://svn.tools.ietf.org/wg/roll/trac/ticket/105#comment:2>
roll <http://tools.ietf.org/wg/roll/>