Browse Prior Art Database

Method of Identifying Real-Time Traffic on Token Ring

IP.com Disclosure Number: IPCOM000116888D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Christensen, KJ: AUTHOR

Abstract

Disclosed is a method of identifying Token Ring frames that are associated with real-time applications. Frames associated with real-time applications may require special high-priority handling at intermediate nodes (e.g., bridges, routers, and switches) and at end systems (e.g., workstation adapters). The disclosed method is simple, low-latency, and does not conflict with existing methods or conventions used in Token Ring applications and networks. FIGURE 1 - Example workstation adapter with top-card bus

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Method of Identifying Real-Time Traffic on Token Ring

      Disclosed is a method of identifying Token Ring frames that are
associated with real-time applications.  Frames associated with
real-time applications may require special high-priority handling at
intermediate nodes (e.g., bridges, routers, and switches) and at end
systems (e.g., workstation adapters).  The disclosed method is
simple, low-latency, and does not conflict with existing methods or
conventions used in Token Ring applications and networks.  FIGURE 1 -
Example workstation adapter with top-card bus

      It is possible that within a workstation adapter special
handling is required for real-time traffic.  For example, real-time
frames may need to be forwarded across a separate top-card bus or
given priority on the system bus.  Data frames (i.e., not real-time
traffic) are always forwarded on the system bus.  Fig. 1 shows a
workstation adapter with a top-card bus.

      The solution to the problem of identifying real-time frames is
to define a new frame type within the first two bits of the Token
Ring Frame Control (FC) field.  Frame types, 00 = Media Access

Control (MAC), and 01 = Logical Link Control (LLC) are already
defined.  LLC is typically data (i.e., not real-time).  A new frame
type, 1X = real-time is defined.  This frame type does not exist on
present Token Ring LANs.  Thus, there is no possible conflict with an
existing method or convention.  This new frame type is not ch...