Browse Prior Art Database

Prioritized Switched Full Duplex Local Area Network Based on Demand Priority

IP.com Disclosure Number: IPCOM000114720D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Allen, JJ: AUTHOR [+2]

Abstract

Demand Priority or 100Base-VG is a 100 Mbps shared media Local Area Network (LAN). It is a hub based system with two priority levels. A round robin protocol is used for each priority level. Access to the network is permitted to only one end node at a time. The bandwidth of the 100Base-VG network is limited to 100 Mbps. The capability of extending the bandwidth of 100Base-VG by using switching to allow more than one end node to access the network is disclosed. The concept of full duplex operation of 100Base-VG is also disclosed.

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Prioritized Switched Full Duplex Local Area Network Based on Demand
Priority

      Demand Priority or 100Base-VG is a 100 Mbps shared media Local
Area Network (LAN).  It is a hub based system with two priority
levels.  A round robin protocol is used for each priority level.
Access to the network is permitted to only one end node at a time.
The bandwidth of the 100Base-VG network is limited to 100 Mbps.  The
capability of extending the bandwidth of 100Base-VG by using
switching to allow more than one end node to access the network is
disclosed.  The concept of full duplex operation of 100Base-VG is
also disclosed.

      Implementations of 100 Base-VG which are compliant to the
proposed IEEE 802.12 standard are half duplex and the bandwidth is
shared among the total number of end nodes.  Demand Priority provides
two priority levels for end nodes to request to transmit: normal
priority and high priority.  Each priority level is controlled by the
hub with a round robin implementation that grants access to the
network to each requesting end node in a round robin sequence.

      By using switching technology, provision can be made to allow
more than one end node to transmit at a time.  For instance, a
switching hub with 200 Mbps bandwidth can be implemented such that
two end nodes can be granted permission to transmit at one time.  A
switching hub with 300 Mbps bandwidth can be implemented such that
three end nodes can be granted permission to transmit at one time.
The round robin priority scheme can be used to grant "N" nodes
permission to transmit at the same time where N equals the switch
bandwidth in Mbps divided by 100.  The fairness of the round robin
scheme can be maintained.  The two priority levels of Demand Priority
can be maintained.  One or more high priority requests can be
serviced simultaneously before or concurrent with normal priority
requests as long as the bandwidth of the switch is not exceeded.

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