VP/VC lookup function
First Claim
1. In an ATM switch of the type that routes cells from an input port to an output port over a virtual connection based at least in part on virtual connection information provided within a cell header, a virtual path/virtual channel lookup process including the following steps:
- (a) hash coding cell virtual connection information including Virtual Path, Virtual Channel and physical link information to provide a reduced length hash code; and
(b) searching for connection information based at least in part on the reduced length hash code.
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Accused Products
Abstract
A new, efficient approach to ATM connection table lookup minimizes the number of tables and memory lookups through use of hash coding and binary table search techniques. The virtual connection information associated with an incoming ATM cell is hash coded. The hash code provides a compressed representation of the virtual connection information--allowing the address space of a table accessed based on the hash code to be much smaller than the maximum number of possible virtual connection combinations that can be encoded in the ATM cell header without restricting the set of possible virtual connection combinations. A binary search based on the cell'"'"'s virtual connection information can be used to efficiently select, from plural records accessed based on the hash code, the particular search record corresponding to the cell'"'"'s connection.
142 Citations
30 Claims
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1. In an ATM switch of the type that routes cells from an input port to an output port over a virtual connection based at least in part on virtual connection information provided within a cell header, a virtual path/virtual channel lookup process including the following steps:
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(a) hash coding cell virtual connection information including Virtual Path, Virtual Channel and physical link information to provide a reduced length hash code; and (b) searching for connection information based at least in part on the reduced length hash code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In an ATM switch of the type that routes cells from an input port to an output port over a virtual connection based at least in part on virtual connection information providing within a cell header, a virtual path/virtual channel lookup arrangement comprising:
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a hash coding block that hash codes cell virtual connection information to provide a reduced length hash code; and a search table that searches for connection information based at least in part on the reduced length hash code. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A virtual path/virtual channel lookup arrangement comprising:
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hash coding means, connected to receive cell virtual connection information, for hash coding the cell virtual connection information to provide a reduced length hash code; and connection information searching means, coupled to receive the reduced length hash code, for searching connection information based at least in part on the reduced length hash code. - View Dependent Claims (25)
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26. A cell routing method including:
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(a) obtaining virtual connection corresponding to a cell; (b) hash coding at least a part of the virtual connection information to provide a reduced length hash code; (c) using the reduced length hash code, directly or indirectly, to look up a binary search tree stored in a search table, the binary search tree being capable of including plural search records; (d) selecting one of the plural search records based at least in part on a comparison between the search record contents and the obtained virtual connection information; (e) obtaining virtual connection information based on the selected search record; and (f) routing the cell through a digital communications network based at least in part on the virtual connection information obtained by step (e). - View Dependent Claims (27)
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28. In an ATM cell routing determination arrangement that hash codes cell virtual connection information including VPI, VCI and physical link information to provide a reduced length hash code, a lookup method comprising:
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(a) looking up a record in a first table based on a combination of both PHY, VPI virtual connection information; (b) searching, based on said reduced length hash code, for a record in a second table based on a combination of the PHY, VPI virtual connection information and VCI virtual connection information; (c) determining based on the first table look up whether the cell has an active virtual path connection; and (d) determining based on the second table look up whether the cell has an active Virtual Channel connection. - View Dependent Claims (29, 30)
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Specification