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MAC Isolator for Wireless Connectivity of IBM Token-Ring Cards

IP.com Disclosure Number: IPCOM000111929D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Christensen, K: AUTHOR [+3]

Abstract

Described is a means of attaching a token-ring card to a wireless LAN. The mechanixm needed to do this is a MAC isolator.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

MAC Isolator for Wireless Connectivity of IBM Token-Ring Cards

      Described is a means of attaching a token-ring card to a
wireless LAN.  The mechanixm needed to do this is a MAC isolator.

A token-ring MAC Isolator performs three key functions:

1.  Prevents MAC frames from leaving the isolator, and thus allows
    each station to operate as a normal IEEE802.5 single station
    token-ring.

2.  Allows the token-ring station to participate in a simple wireless
    polling-based protocol.  The polling-based protocol is not
    IEEE802.5.

3.  Interfaces to a wireless physical layer that can have a data rate
    of less than the data rate of the token-ring card.

The Figure is a functional diagram of the token-ring MAC isolator

The functions of the different blocks in the Figure are:

RF Transmitter:

o   The Radio Frequency (RF) transmitter transmits a token-ring data
    frame read from the FIFO buffer.

RF Receiver:

o   The RF receiver receives token-ring data frames and writes the
    frame to the FIFO buffer.

o   The RF receiver also receives poll sequences, possibly from a
    central hub (not shown).  When a matching poll sequence is
    detected, a "poll received" signal is sent to block #3.

First-In First-Out (FIFO) Buffers:

o   The FIFO buffers for transmit and receive allow "speed matching"
    the 4- or 16-Mbps token-ring data rate and the slower wireless
    data rate.

Block #1:

o   If the start of a non-MAC frame is detected, write the frame into
    the transmit FIFO buffer.

o   Wrap all frames and tokens to block #2.

Block #2:

o   For all passing tokens, set t...