[ANCP] Mixing and matching of multicast modes of operation (capabilities)

[Tom Taylor <tom111.taylor at bell.net>]

I am currently creating a version of the multicast extensions document 
implementing the capabilities I described in my August E-mails. Just to review, 
I saw four multicast capabilities:

- NAS-controlled multicast replication;
- conditional access with white and black lists;
- conditional access with grey lists;
- flexible bandwidth sharing, AKA bandwidth delegation.

I would like comments on the following statements:

1) If a particular capability is negotiated, it applies to all ports. Thus, for 
example, if NAS-controlled multicast replication is negotiated between the NAS 
and AN, it will be used on all of the AN's ports.

2) As a consequence of 1), I believe NAS-controlled multicast is incompatible 
with (mutually exclusive to) the other multicast capabilities on a specific 
adjacency.

3) The other three capabilities can operate by themselves or in any combination. 
They have in common that:
-- Join/leave requests are terminated by the AN.
-- The AN performs admission control.

Where they are operating on their own, these capabilities are defined as follows:

Conditional access in general:
It is assumed that the AN is configured with per-subscriber bandwidth limits and 
the bandwidth required for a given multicast channel, by means out of scope of ANCP.

   Conditional access with white and black lists:
   ---------------------------------------------
   The AN accepts white-listed join requests without consulting the NAS, and
   ignores all other join requests.

   Conditional access with grey lists:
   ----------------------------------
   For grey-listed join requests only, the AN performs admission control but
   then requests permission from the NAS before initiating replication. The AN
   ignores all other join requests.

Flexible bandwidth sharing AKA bandwidth delegation:
---------------------------------------------------
The AN performs admission control and accepts the request if sufficient 
multicast bandwidth is available. That is, the AN acts as if every multicast 
channel is white-listed. Admission control is against a total multicast 
bandwidth limit negotiated with the NAS, but it is assumed that the AN is 
configured with the bandwidth required for a given multicast channel by means 
out of scope of ANCP.

When the capabilities are combined, the behaviour is as follows:

Conditional access with white and black lists combined with conditional access 
with grey lists:
-------------------------------------------------------------
The rules specified in the framework document for finding best match are 
applied. If the match is to a white list entry, the AN accepts the request 
(subject to admission control) without consulting the NAS. If the match is to a 
grey list entry, the AN performs admission control but then requests permission 
from the NAS before initiating replication. All other join requests are ignored.

Flexible bandwidth sharing AKA bandwidth delegation with any combination of 
conditional access capabilities:
-------------------------------------------------------------
AN behaviour is the same as defined by the conditional access capabilities 
within the combination, with the additional behaviour of multicast bandwidth 
negotiation with the NAS.

4) If a capability is negotiated, it is activated. You don't need an explicit 
activation as we currently have with bandwidth delegation.

Tom Taylor