Method for maintaining virtual local area networks with mobile terminals in an ATM network
First Claim
1. In an asynchronous transfer mode (ATM) network, wherein a plurality of virtual local area network (VLAN) server nodes are connected by virtual channels into plural trees, wherein at least some of said VLANs comprise base stations (BSs) capable of providing packet communication for one or more mobile terminals (MTs), a method of tracking a location of each MT comprising the steps of:
- (a) maintaining in an original BS (BSorig) on an original VLAN (VLANorig) a record corresponding to each MT for which said BSorig provides packet communication which record contains an identifier (VLAN-ID) of one of said VLANs which said MT is on (VLAN-ID(MT)),(b) transmitting a message frame, from said BSorig which currently provides packet communication for an MT, to a server node of said VLANorig, said message frame, containing said VLAN-ID(MT), a VLAN-ID of a new VLAN (VLANnew) and an ATM address of said BSorig (ATM(BSorig)),(c1) if said MT is on said VLANorig, increasing said number of MTs on VLANorig which have moved; and
(c) receiving said message frame at said server node of said VLANorig and updating a mobility terminal membership tracking database (MTD) maintained at said server node to reflect said movement of said MT.
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Abstract
A method and system are provided for implementing virtual local area networks (VLANs) over ATM using LAN over ATM emulation technology. Server nodes which provide address registration/resolution and which enable multicast and broadcast routing on each VLAN are interconnected into multiple trees. The root server nodes of each tree are interconnected according to a hypercube topology. Data structures for maintaining the locations and routing information of mobile terminals is provided. Methods for constructing and updating the data structures when a mobile terminal moves from location to another also provided. Methods are also provided for routing packets using the data structures to and from mobile terminals.
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Citations
24 Claims
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1. In an asynchronous transfer mode (ATM) network, wherein a plurality of virtual local area network (VLAN) server nodes are connected by virtual channels into plural trees, wherein at least some of said VLANs comprise base stations (BSs) capable of providing packet communication for one or more mobile terminals (MTs), a method of tracking a location of each MT comprising the steps of:
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(a) maintaining in an original BS (BSorig) on an original VLAN (VLANorig) a record corresponding to each MT for which said BSorig provides packet communication which record contains an identifier (VLAN-ID) of one of said VLANs which said MT is on (VLAN-ID(MT)), (b) transmitting a message frame, from said BSorig which currently provides packet communication for an MT, to a server node of said VLANorig, said message frame, containing said VLAN-ID(MT), a VLAN-ID of a new VLAN (VLANnew) and an ATM address of said BSorig (ATM(BSorig)), (c1) if said MT is on said VLANorig, increasing said number of MTs on VLANorig which have moved; and (c) receiving said message frame at said server node of said VLANorig and updating a mobility terminal membership tracking database (MTD) maintained at said server node to reflect said movement of said MT. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 20)
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9. The method of claim wherein step (c) further comprises the steps of:
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(c1) if said MT is on said VLANnew, decreasing said number of MTs on VLANnew which have moved into proximity of, and which are provided packet communication by, a BS of a VLAN other than VLANnew in said OUT-MTD, and (c2) otherwise, using VLAN-ID(MT) and said ATM address of said BSnew, in said message frame as indexes for retrieving a corresponding entry of said IN-MTD, (c3) if no entry is retrieved in step (c2), creating an entry in said IN-MTD containing said VLAN-ID(MT) as said VLAN-ID of said corresponding entry, said ATM address of said BSnew as said ATM address of said particular BS that provides packet communication for each of said MT'"'"'s to which said entry pertains, and a VCC for communicating to said BSorig as said VCC of said particular BS to which said entry pertains, and (c4) increasing said count of said number of MTs on said corresponding VLAN currently in a proximity of, and being provided packet communication by said particular BS of VLANnew, in said IN-MTD entry indexed by said VLAN-ID(MT) and said ATM address of said BSnew.
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10. In an asynchronous transfer mode (ATM) network, wherein a plurality of virtual local area network (VLAN) server nodes are connected by virtual channels into plural trees, wherein at least some of said VLANs comprise base stations (BSs) capable of providing packet communication for one or more mobile terminals (MTs), a method of communicating packets comprising the steps of:
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(a1) receiving a message frame from an original BS (BSorig) which originally provided packet communication for a moving MT, at a server node original VLAN (VLANorig) containing said BSorig, (a) receiving a packet containing a destination VLAN identifier (VLAN-ID) at a server node of a VLAN, (b1) if said MT is on said VLANorig, increasing said number of MTs on VLANorig which have moved, (b) if said server node is not a root node of a tree, transmitting said packet to a parent server node of said tree, and (c) otherwise if said server node is a root node of said tree; (d) accessing an inter-tree-MTD maintained at said server node, to determine each other tree containing at least one MT on said VLAN identified by said destination VLAN, and (e) transmiting a copy of said packet to each of said trees identified in said step (d). - View Dependent Claims (11, 12, 13, 14, 15, 21)
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16. In an asynchronous transfer mode (ATM) network, wherein a plurality of virtual local area network (VLAN) server nodes are connected by virtual channels into plural trees, wherein at least some of said VLANs comprise base stations (BSs) capable of providing packet communication for one or more mobile termiinals (MTs), a method of tracking a location of each MT comprising the steps of:
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(a1) maintaining in an original BS (BSorig) on an original VLAN (VLANorig) a record corresponding to each MT for which said BSorig provides packet communication which record contains an identifier (VLAN-ID) of one of said VLANs which said MT is on (VLAN-ID(MT)), (a) maintaining an inter-tree MT membership tracking database (inter-tree-MTD) at a root server node, containing at least one entry, each entry of said inter-tree-MTD corresponding to a different one of said VLANs and containing; (i) an identifier of the corresponding VLAN (VLAN-ID), and (ii) a count of the number of MTs of the VLAN corresponding to said entry which are contained in each tree, (b) in response to receiving at said root server node a message frame indicating that a MT has moved from a proximity of a BS in an original tree (Treeorig) to a proximity of another BS in a new tree (Treenew); (c) retrieving an entry of said inter-tree-MTD of said root server node corresponding to a VLAN-ID of the VLAN that said moving MT (VLAN-ID(MT)) is on, (d) decreasing a count of said retrieved entry associated with Treeorig and increasing a count of said entry associated with Treenew, wherein if said MT is on said VLANorig, increasing said number of MTs on VLANorig which have moved. - View Dependent Claims (22)
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17. In an asynchronous transfer mode (ATM) network, wherein a plurality of virtual local area network (VLAN) server nodes are connected by virtual channels into plural trees, wherein at least some of said VLANs comprise base stations (BSs) capable of providing packet communication for one or rmore mobile terminals (MTs), a method of tracking a location of each MT comprising the steps of:
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(a) receiving a message frame from an original BS (BSorig) which originally provided packet communication for a moving MT, at a server node of an original VLAN (VLANorig) containing said BSorig, said message frame indicating an identifier of one of said VLANs which said MT is on (VLAN-ID(MT)), a new VLAN (VLANnew) containing a new BS (BSnew) into a proximity of which said MT moves, and which will provide packet communication for said MT, and an ATM address of said BSorig. (b) updating a mobile terminal membership tracking database (MTD) maintained at said server node to reflect said movement of said MT, wherein if said MT is or said VLANorig, increasing said number of MTs on VLANorig which have moved. - View Dependent Claims (18, 23)
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19. An asynchronous transfer mode (ATM) communications network comprising:
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a plurality of server nodes interconnected by virtual channels (VCs) into a plurality of trees, a plurality of base stations (BSs) including a first BS connected by a first legacy local area network (LAN) to a first one of said server nodes, a plurality of terminals connected to said first legacy LAN, including a mobile terminal (MT) which registers with, and is provided packet service by, said first BS when said MT is in a proximity of said first BS, wherein a message frame from an original BS, (BSorig) which originally provided packet communation for a moving MT is received at a sever node of an original VLAN (VLANorig) containing said BSorig, wherein if said MT is on said VLANorig increasing said number of MTs on VLANorig which have moved. wherein said BS'"'"'s, MTs sever nodes and terminals are organized into plural virtual local area networks (VLANs), and wherein each root server node maintains information regarding which of said trees contains said first MT so as to enable routing packets to and from said MT. - View Dependent Claims (24)
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Specification