Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1997-07-08
2001-10-09
Ngo, Ricky (Department: 2644)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S400000
Reexamination Certificate
active
06301267
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to apparatus and methods for utilizing communication networks.
BACKGROUND OF THE INVENTION
Currently marketed switches and cross-connects are non-blocking. Examples include Alcatel's 1100 (HSS and LSS), 1641 and 1644 switches, AT&T's II and DACS III switches (Lucent technology), TITAN's 5300 and RN64 series, Siemens EWSXpress 35190 ATM Core Switch and Switching Faulty CC155 systems, Newbridge's 3600, 3645, 36150 and 36170 MainStreet switches and the Stinger family of ATM switches.
A review of ATM (asynchronous transfer mode) switching products, namely “The ATM Report”, Broadband Publishing Corporation, ISSN 10720981X, 1996 surveys 10 switches of which nine are completely non-blocking and one, CISCO, has a positive but very low blocking probability (3% probability of blocking at 2 Gbps).
The ITU-T Recommendation G.782 (International Telecommunication Union, Telecommunication Standardization Sector, 01/94) includes Section 4.5 entitled “Blocking” which states:
“The existence of cross-connections in a cross-connect equipment can prevent the set-up of a new cross-connection. The blocking factor of a cross-connect is the probability that a particular connection request cannot be met, normally expressed as a decimal fraction of 1. Fully non-blocking (i.e. blocking factor=0) cross-connects can be built. Some simplification in design, and hence cost, can be realized if a finite blocking factor is acceptable. It is not the invention of this Recommendation to specify target blocking factors for individual cross-connect equipment. The impact of non-zero blocking factor on network performance is dependent on network design and planning rules.
“There is a class of cross-connect matrices known as conditionally non-blocking in which there is a finite probability that a connection request may be blocked. In such cross-connects, it is possible, by re-arranging existing connections, to make a cross-connection which would otherwise be blocked. As an objective, in such cases, rearrangements should be made without interruption to rearranged paths.
“It may be necessary in a nominally non-blocking, or conditionally non-blocking cross-connect, to accept some blocking penalty associated with extensive use of broadcast connections. This is for further study.”
A later document “ATM functionality in SONET digital cross-connect systems—generic criteria”, Generic Requirements CR-2891-CORE, Issue Aug. 1, 1995, Bellcore (Bell Communications Research) states as a requirement that “A SONET DCS with ATM functionality must meet all existing DCS requirements from TR-NWT-000233”. The TR-NWT-000233 publication (Bellcore, Issue Nov. 3, 1993, entitled “Wideband and broadband digital cross-connect systems generic criteria”) stipulates the following requirement (R) 4-37:
“For a two-point unidirectional cross-connection, non-blocking cross-connection shall be provided. Non-blocking means that a cross-connection can be made regardless of other existing connections. Rearranging the existing cross-connections to accommodate a new cross-connection is acceptable only if the rearrangement is performed without causing any bit error for the rearranged cross-connections.”
The disclosures of all publications mentioned in the specification and of the publications cited therein are hereby incorporated by reference.
SUMMARY OF THE INVENTION
The present invention seeks to provide methods and apparatus for expanding the capacity of a network.
There is thus provided in accordance with a preferred embodiment of the present invention a method for increasing the total capacity of a network, the network including a first plurality of communication edges (communication links) interconnecting a second plurality of communication nodes (transceivers), the first plurality of communication edges and the second plurality of communication nodes having corresponding first and second pluralities of capacity values respectively. The first and second pluralities of capacity values form corresponding topologies which determine the total capacity of the network. The method includes expanding the capacity value of at least an individual communication edge from among the first plurality of communication edges, the individual edge connecting first and second communication nodes from among the second plurality of communication nodes, without expanding the capacity value of the first communication node.
In conventional methods, to expand total capacity, the capacities of at least a subset of nodes is expanded, plus the capacities of all edges and only those edges which connect a pair of nodes within that subset.
There is thus provided, in accordance with a preferred embodiment of the present invention, a method for increasing the total capacity of a network, the network including a first plurality of communication edges interconnecting a second plurality of communication nodes, the first plurality of communication edges and the second plurality of communication nodes having corresponding first and second pluralities of capacity values respectively, the first and second pluralities of capacity values determining the total capacity of the network, the method including expanding the capacity value of at least an individual communication edge from among the first plurality of communication edges, the individual edge connecting first and second communication nodes from among the second plurality of communication nodes, without expanding the capacity value of the first communication node.
Further in accordance with a preferred embodiment of the present invention, the method includes performing the expanding step until the total capacity of the network reaches a desired level, and expanding the capacity values of at least one of the second plurality of communication edges such that all of the second plurality of communication edges have the same capacity.
Also provided, in accordance with another preferred embodiment of the present invention, is a method for expanding the total capacity of a network, the network including a first plurality of communication edges interconnecting a second plurality of communication nodes, the first plurality of communication edges and the second plurality of communication nodes having corresponding first and second pluralities of capacity values respectively, the first and second pluralities of capacity values determining the total capacity of the network, the method including determining, for each individual node from among the second plurality of communication nodes, the amount of traffic entering the network at the individual node, and, for each edge connected to the individual node, if the capacity of the edge is less than the amount of traffic, expanding the capacity of the edge to the amount of traffic.
Also provided, in accordance with another preferred embodiment of the present invention, is a method for constructing a network, the method including installing a first plurality of communication edges interconnecting a second plurality of communication nodes, and determining first and second pluralities of capacity values for the first plurality of communication edges and the second plurality of communication nodes respectively such that, for at least one individual node, the sum of capacity values of the edges connected to that node exceeds the capacity value of that node.
Further provided, in accordance with another preferred embodiment of the present invention, is a network including a first plurality of communication edges having a first plurality of capacity values respectively, and a second plurality of communication nodes having a second plurality of capacity values respectively, wherein the first plurality of communication edges interconnects the second plurality of communication nodes such that, for at least one individual node, the sum of capacity values of the edges connected to that node exceeds the capacity value of that node.
Also provided, in accordance with yet another preferred embodiment of the present invention, is a method for a
Abelman ,Frayne & Schwab
Ngo Ricky
Urizen Ltd.
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