Browse Prior Art Database

Minimized First Access Delay in Buffer Insertion Lans

IP.com Disclosure Number: IPCOM000107671D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 71K

Publishing Venue

IBM

Related People

Lemppenau, WW: AUTHOR [+2]

Abstract

Consider a buffer insertion LAN in which frames already on the medium have priority over frames pending for transmission. A fairness mechanism (1,2) guarantees all nodes to obtain a fair medium access and to periodically have an empty insertion buffer. During heavy load periods, this mode of operation tends to cause excessive frame access delays for a low traffic user which communicates interactively with another node. Then, as Fig. 1 illustrates, access to the medium may be forced to be deferred until a continuous stream of passing frames terminates owing to the fairness mechanism. The length of that stream of back-to-back frames strongly depends on the number of active users, their demand requirements, the maximum frame size used, and the occupancy of the insertion buffers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Minimized First Access Delay in Buffer Insertion Lans

       Consider a buffer insertion LAN in which frames already
on the medium have priority over frames pending for transmission.  A
fairness mechanism (1,2) guarantees all nodes to obtain a fair medium
access and to periodically have an empty insertion buffer.  During
heavy load periods, this mode of operation tends to cause excessive
frame access delays for a low traffic user which communicates
interactively with another node.  Then, as Fig. 1 illustrates, access
to the medium may be forced to be deferred until a continuous stream
of passing frames terminates owing to the fairness mechanism.  The
length of that stream of back-to-back frames strongly depends on the
number of active users, their demand requirements, the maximum frame
size used, and the occupancy of the insertion buffers.

      Quasi-immediate access is, however, achievable by a
preferential treatment of these low traffic users during a "first
transmission period" in which pending frame transmissions are allowed
to be inserted between two passing frames.  Fig. 2 shows an inserted
transmission of a frame requiring a transmission time Tx .  To avoid
data loss within the network, such an inserted transmission always
requires that the insertion buffer has space enough to hold up frames
from the medium during the node's frame transmission.

      All frames to be transmitted by a node during a "first
transmission period" are marked.  Frames...