Patent EP0817424A2 successfully refreshed from Google Patents.
EP0817424A2
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EP
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High-speed mesh connected local area network
Assignee: Compaq Computer Corp
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Filing: 1990-05-16
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Granted: —
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Expires: 2010-05-16
Abstract
Abstract A mesh connected local area network provides automatic packet switching and routing between host computers coupled to the network. The network has a multiplicity of cut-through, nonblocking switches, each capable of simultaneously routing a multiplicity of data packets. Low host-to-host latency is achieved through the use of cut-through switches with separate internal buffers for each packet being routed. The switches are interconnected with one another and are coupled to the host computers of the network by point to point full duplex links. While each switch can be coupled to ten or more network members, i.e., switches and hosts, each link is coupled to only two network members and is dedicated to carrying signals therebetween. Whenever a new switch or link is added to the network, and whenever a switch or link fails, the switches in the network automatically reconfigure the network by recomputing the set of legal paths through the network.
Inventors
- 👤 Hallam G. Murray, Jr.
- 👤 Charles P. Thacker
- 👤 Edwin H. Satterthwaite, Jr.
- 👤 Michael D. Schroeder
- 👤 Andrew D. Birrell
- 👤 Roger M. Needham
- 👤 Thomas L. Rodeheffer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 21:16
CPC Classifications
H; H04; H04L; H04L45/00; H04L45/02; H04L12/00; H04L12/28; H04L45/16; H04L45/28; H04L45/48; H04L49/00; H04L49/35; H04L49/351; H04L12/44; H04L2012/445; H04L49/10; H04L49/101; H04L49/20; H04L49/201; H04L49/25; H04L49/251; H04L49/30; H04L49/3009
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
470 words
A mesh connected local area network for interconnecting a multiplicity of hosts,
said network comprising: a multiplicity of switch means (124, 126, 140, 142, 210) for simultaneously
routing a multiplicity of data packets between hosts (120, 132, 134, 136, 138) in the
network; a multiplicity of point to point link means (128) for interconnecting said switch
means and the hosts in said network, each point to point link means (128) providing a
communication channel between two of said network members; each switch means coupled to one another switch means by said link means
comprising a neighboring switch means; characterized by: said multiplicity of link means (128) including spanning tree links and a
multiplicity of additional links; said multiplicity of switch means (124, 126, 140, 142) and said spanning tree
links together comprising a spanning tree in which one of said switch means is
designated the root (710) of said spanning tree; each switch means including reconfiguration means (900) for determining the
position of said switch means in said spanning tree, said reconfiguration means
including: position denoting means (920) for denoting a tree position within said
spanning tree; epoch denoting means (950) for denoting an epoch value associated
with said tree position; configuration change detection means (800) for detecting a change in
the configuration of said network, including detecting the existence of a new
connection between said switch means and another one of said network members
and detecting the breaking of a connection between said switch means and another
one of said network members; reconfiguration initiation means (1000) for incrementing said epoch
value when a change in the configuration of said network is detected and for sending
a configuration message (904) to each said neighboring said switch means; said
configuration message including said tree position and said epoch value; configuration message processing means (1004) for receiving
configuration messages (904) from said neighboring switch means, for generating a
derived tree position which is a function of the tree position in each received
configuration message, and for replacing the tree position denoted by said position
denoting means with said derived tree position when said derived tree position is
better than the tree position denoted by said position denoting means; said configuration message processing means (1004) replacing said
tree position with said derived tree position and replacing said epoch value with the
epoch value in said received configuration message when said epoch value in said
received configuration messages is larger than the epoch value denoted by said
epoch denoting means (950), and sending a configuration message to said
neighboring switch means when said tree position denoted by said position denoting
means is replaced by said derived tree position; whereby changes in the configuration of the network automatically cause the
switch means in said network to redetermine their relative tree positions in said
spanning tree.
Claim 2
Dependent Claim
136 words
The mesh connected local area network of claim 1, further characterized by: said configuration change detection means including suicide pact means for
detecting epoch value overflow when said epoch value is incremented to a predefined
overflow value, and for sending a predefined suicide pact message to said
neighboring switch means and for resetting said epoch value to a predefined initial
value when epoch value overflow is detected; and said configuration message processing means including means for responding
to the receipt of a suicide pact message by resetting said epoch value to said
predefined initial value, sending said predefined suicide pact message to said
neighboring switch means, ignoring all subsequent suicide pact messages received
from said neighboring switch means for a predefined period of time, and then sending
a configuration message to each said neighboring switch means.
Claim 3
Dependent Claim
82 words
The mesh connected local area network of claim 1 or 2, further characterized
by: said reconfiguration initiation means including status filter means, coupled to
said configuration change detection means, for preventing said sending of said
configuration messages to said neighboring switch means, whenever said
configuration change detection means detects a new connection between said switch
means and another one of said network members, until passage of a defined time
interval; whereby disruption of said network by an intermittently operative connection is
limited.
Claim 4
Dependent Claim
43 words
The mesh connected local area network of claim 3, wherein said defined time
interval is a time interval that begins when one of said point to point link means,
corresponding to said new connection detected by said configuration change
detection means, becomes operative.
Claim 5
Dependent Claim
75 words
The mesh connected local area network of claim 1, further characterized by: said configuration message process means of all said switch means
collectively transmitting to all of said switch means network configuration data
indicating the tree positions of all said switch means in said spanning tree; and each switch means including route selection means for routing received data
packets to specified network members in accordance with said network configuration
data and predefined route selection criteria.
Claim 6
Independent Claim
463 words
A method of operating a mesh connected local area network, the network
including a multiplicity of switch means (124, 126, 140, 142, 210) for simultaneously
routing a multiplicity of data packets between hosts (120, 132, 134, 136, 138) in the
network, said hosts and switch means together comprising network members; and a multiplicity of point to point link means (128) for interconnecting said switch
means and the hosts in said network, each point to point link means (128) providing a
communication channel between two of said network members; each switch means coupled to one another switch means by said link means
comprising a neighboring switch means; said method comprising the steps of: configuring said network members so as to generate routing data for routing
data packets between said network members; characterized by: configuring said network members as a spanning tree in which one of said
switch means is designated the root (710) of said spanning tree and in which said
multiplicity of link means (128) includes spanning tree links that are part of said
spanning tree and a multiplicity of additional links that are not a part of said spanning
tree; at each switch means, performing the steps of: denoting a tree position associated with said switch means within said
spanning tree; denoting
an epoch value associated with said tree position; detecting a change in the configuration of said network, including
detecting the existence of a new connection between said switch means and another
one of said network members and detecting the breaking of a connection between
said switch means and another one of said network members; incrementing said epoch value when a change in the configuration of
said network is detected and sending a configuration message (904) to each said
neighboring said switch means; said configuration message including said tree
position and said epoch value; receiving configuration messages (904) from neighboring switch means,
generating a derived tree position which is a function of the tree position in each
received configuration message, and replacing the tree position denoted by said
position denoting means with said derived tree position when said derived tree
position is better than the tree position denoted by said position denoting means; replacing said tree position with said derived tree position and replacing
said epoch value with the epoch value in said received configuration message when
said epoch value in said received configuration messages is larger than the epoch
value denoted by said epoch denoting means (950), and sending a configuration
message to said neighboring switch means when said tree position denoted by said
position denoting means is replaced by said derived tree position; whereby changes in the configuration of the network automatically cause the
switch means in said network to redetermine their relative tree positions in said
spanning tree.
Claim 7
Dependent Claim
116 words
The method of claim 6, further characterized by: at each switch means: detecting epoch value overflow when said epoch value is incremented to
a predefined overflow value, and sending a predefined suicide pact message to said
neighboring switch means and resetting said epoch value to a predefined initial value
when epoch value overflow is detected; and responding to the receipt of a suicide pact message by resetting said
epoch value to said predefined initial value, sending said predefined suicide pact
message to said neighboring switch means, ignoring all subsequent suicide pact
messages received from said neighboring switch means for a predefined period of
time, and then sending a configuration message to each said neighboring switch
means.
Claim 8
Dependent Claim
69 words
The method of claim 6 or 7, further characterized by: whenever said configuration change detection means detects a new
connection between said switch means and another one of said network members,
preventing said sending of said configuration messages to said neighboring switch
means until passage of a defined time interval during which said new connection
remains operative; whereby disruption of said network by an intermittently operative connection is
limited.
Claim 9
Dependent Claim
59 words
The method of claim 6, further characterized by: said switch means collectively transmitting to all of said switch means network
configuration data indicating the tree positions of all said switch means in said
spanning tree; and each switch means routing received data packets to specified network
members in accordance with said network configuration data and predefined route
selection criteria.
References Cited (Backward Citations)
No citation records indexed.
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