Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
However, the processing of such information in order to negotiate the best possible features used in the
communications network is beyond the aim of this protocol.
From the point of view of packet format and message exchange, this protocol is an extension of the Port Solver
protocol (PSP). It uses reserved fields in Port Solver Messages (PSMs) to place node capabilities information, and
shall not prevent the ordinary working of the PSP protocol. Some additions shall be applied to the PSM exchange
mechanism in order to fulfill the features of the Capabilities Exchange protocol.
The Capabilities Exchange protocol shall be flexible enough, not only to provide the exchange of specific
capabilities from different vendors, but also to allow the exchange of a standard set of minimum capabilities
common for all vendors. Moreover, it shall be easily extensible to include new capabilities, which shall not prevent
backwards compatibility.
This protocol should be efficient, regarding the channel use, to minimize the impact of the overhead of the protocol
in the application data throughput of the whole network.
9.1.4.5.2 Protocol
The protocol is composed by two main stages:
• First stage: Two nodes shall exchange the information about the maximum capabilities they can perform
and the capabilities they are running at that time. In this stage, it is used an ACK-based protocol whose
objective is to fill two local tables in each node indexed by MAC address:
o Node Capability Table (NCT): It shall contain the maximum capabilities of each known node.
o Performed Capability Table (PCT): It shall contain the capabilities that each known node is running
at that time.
The implementation of these two tables should be done in a single table with the contents described in
section 0 and 0. The two tables are divided into four sections:
o Common capabilities
o Chip related capabilities
o Reference Design related capabilities
o Firmware related capabilities
The first section (Common) shall be common for all systems, independent of the vendor. The last three ones
(Chip, Reference Design and Firmware related) shall depend on the vendor. The maximum number of
entries of each section shall be 64, with an unlimited size per entry.
• Second stage: It shall take place only if the running capabilities of a node change. This node shall indicate
all nodes the new capabilities that it is performing at that time. This second stage may be either ACK-based
or not, with a first information message and a received ACK from the destination, depending on the content
of the ACK expected field. If it is 1, an ACK is expected. If not, no ACK is expected from the receiver.
9.1.4.5.3 Messages
Submission page 219 UPA-OPERA