User`s manual

CLARION M10 SERIES INTRODUCTION
M10 SERIES USER’S MANUAL PAGE 2
upgraded feature of the M10II is the extension of retransmission protocol to
multi-source address situations.
This key new feature of the M10II required substantial development. In
wired communications frames are lost mainly by collisions. However, in
wireless communications frames can be lost by fading, weak signals or
interference. Thus, all radio modems require lower level retransmission of
frames to provide adequate reliability and throughput. The original M10
was designed for connection to a single Ethernet card, either in a
workstation or a router. Both the workstation and the router employ a
single 802.3 source address that the M10 learns and uses for the
retransmission protocol. Thus, when the M10 receives a frame with the
destination address equal to the address of the attached Ethernet card, the
M10 sends the RF acknowledgment frame to the source modem. The
M10II can do this for multiple Ethernet source addresses.
There are two important situations in which the above single-source-
address constraint is violated: 802 MAC (media access control) level
bridging and wireless interconnection of 10BaseT hubs. Each of these is
important for general networking, and each presents the modem with
multiple source addresses from the wired side. The M10II maintains a list
of its wired side source addresses, and will acknowledge RF frames
addressed to these. Thus, the key new feature of the M10II is extension of
the retransmission protocol to multi-source-address configurations.
The M10II maintains acknowledgment-address tables, however, it is not a
bridge. For 802-compliant bridging the M10II can be connected to a MAC
bridge, with the MAC bridge providing address tables obtained via the
spanning-tree algorithm.