Implementing multicasting support in the current Linux-ATM driver involves a lot of changes and great knowledge of the driver's internals as well as an understanding of the ATM and IP specifications. An estimation of the amount of time required to form a basic understanding of these matters, enough to implement a working system, is between two and four months.
For an implementation of the RFC 2022 specification in the Linux-ATM system, several choices have to be made: Whether to wait for functionality to become available, to implement that functionality properly in the signalling entity or to add it using a temporary solution. Although it may take longer to get results, implementing point-to-multipoint VCC support in the signalling entity to comply with the RFC 2022 specification, would seem the best way to get a result that can be used in the long term.
The implementation of RFC 2022 within the current IP over ATM system
will cost much time. The time to implement the complete
functionality of a RFC 2022 compliant system is probably
about one to two
years (for a single person). If only a part of the functionality is
implemented, it would still take a long time to get to know the
Linux-ATM system and the protocols involved. A minimum of six months for
an implementation of just one module of the RFC 2022 specification
seems reasonable, including the time it takes to get to know the
protocols and sources. The time to develop the implementation could be
shortened by having several persons work on the different modules in
close cooperation. The sharing of experiences with working with the
Linux-ATM code between them would shorten the learning curve.
The addition of point-to-multipoint support to the signalling entity may
not be very hard to do, considering the current state of the signalling
implementation, see Section 
. For a more precise
evaluation of the time required to make the necessary modifications
mentioned in this chapter, more digging into the source code is
required.