Capwap Mailing List: Bindings issue

[Bob O'Hara (boohara) (boohara]

I believe there is an issue we need to address before the -00 draft is
produced.  This relates to the decision by the working group that the
original CAPWAP protocol would restrict itself to supporting only
802.11, but would provide extensibility to support other wireless
protocols.  This support for extensibility is insufficient in the LWAPP
draft and, without direction from the working group, from the -00 CAPWAP
draft as well.

In the current draft of the LWAPP proposal, all message element
identifiers in the protocol are drawn from a single, 16-bit, number
space.  This does not provide for parallel development of bindings for
different protocols or an unambiguous way to allocate these identifiers
without some central administration of the entire message identifier
number space.

I propose that we add a binding identifier to each message element.
This identifier would, in the -00 draft, place each message element into
either the "base protocol" number space or the "IEEE 802.11" number
space.  It would also allow for reuse of the values in the message
identifier field.  

Alternatively, we could create a "Binding Separator" message element.
This element would separate message elements in the base portion of the
protocol from those defined in a binding.  The value carried by the
separator would identify the specific binding for the elements that
follow the separator, either to the next separator element or to the end
of the packet.

Either alternative for this proposal would require administration of the
binding identifier number space.  But, that number space would most
likely last much longer than the message identifier space, itself, if
left as a single common number space for all bindings to share.

 -Bob

Bob O'Hara
Cisco Systems - WNBU

Phone:  +1 408 853 5513
Mobile: +1 408 218 4025