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On-line Ordering and Testing of Address Labels in Gbit/s LANs

IP.com Disclosure Number: IPCOM000110061D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 144K

Publishing Venue

IBM

Related People

Lemppenau, WW: AUTHOR [+2]

Abstract

The preceding article describes a method to broadcast address-labels (as well as other relevant information) of all active nodes as an integral part of a reservation-based MAC Protocol for Gbit/s ring and bus LANs with a slotted transmission structure (*). This information, which may be updated during each reservation cycle, reflects the topological position (and optionally the load condition) of the active nodes in the network. It can therefore be used: (1) for network management, (2) for minimum hop routing on a dual ring in order to select the ring with the minimum number of active nodes on the path between source and destination, and (3) for the decision to transmit in passing free slots under the condition that the transmission does not pass a given destination.

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On-line Ordering and Testing of Address Labels in Gbit/s LANs

       The preceding article describes a method to broadcast
address-labels (as well as other relevant information) of all active
nodes as an integral part of a reservation-based MAC Protocol for
Gbit/s ring and bus LANs with a slotted transmission structure (*).
This information, which may be updated during each reservation cycle,
reflects the topological position (and optionally the load condition)
of the active nodes in the network.  It can therefore be used: (1)
for network management, (2) for minimum hop routing on a dual ring in
order to select the ring with the minimum number of active nodes on
the path between source and destination, and (3) for the decision to
transmit in passing free slots under the condition that the
transmission does not pass a given destination.  As the following
article describes, such a free slot may carry an address-label to
indicate a reservation for a specific node.

      To prevent renumbering of address-labels, when the network is
reconfigured after a link or node failure or when a new node is
inserted, it is crucial to provide on-line mapping of arbitrarily
numbered address-labels to the topological order on the ring or bus.
Before detailing the mapping technique, we first summarize the
integrated method to broadcast address-labels which we further
shortly reference as addresses.

      Fig. 1 shows a ring with five active nodes as well as a
scheduler to ensure fair allocation of the network capacity.  Nodes
are arbitrarily numbered.  With respect to the position of the
scheduler, nodes 13 and 2 are upstream and nodes 5 and 3 are
downstream from node 8.  The topological order as viewed by the
considered node 8 is, however, (8)-5-3-13-2.  To regulate fair access
to the network, the scheduler issues at a given time a Reserve
command consisting of Start delimiter, all the active node addresses
(13-2-8-5-3), separator, and End delimiter.  Each node removes its
address from and inserts its reservation request into the passing
Reserve command.  As shown for node 8, address removal is after the
Start delimiter and request insertion is before the End delimiter.
The separator thereby moves towards the Start delimiter.  By copying
all addresses up to the separator, node 8 also knows the topological
sequence of its downstream nodes 5 and 3.  Upon return to the
scheduler, the Reserve command only contains request entries.  These
reservation requests are processed.  Subsequently, the scheduler
issues a Confirm command consisting of Start delimiter, se...