Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1997-03-19
2001-10-09
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S392000
Reexamination Certificate
active
06301257
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to the field of data networks. In particular, the present invention is related to an improved method and apparatus for transmitting data frames between nodes connected to a meshed data network having permanently interconnected switches.
2. Description of the Related Art
Traditional data networks include the Ethernet/IEEE 802.3 Local Area Networks (LAN) and IEEE 802.5 Token Ring LAN. These LANs comprise a connectionless oriented shared medium over which unicast and broadcast packets are transmitted. In contrast, an Asynchronous Transfer Mode (ATM) network comprises a connection oriented packet switched network.
Communication between nodes (e.g., workstations, servers, bridges, etc.) on separate LANs interconnected via an ATM network or between a node on the ATM network and a node on the LAN wherein the ATM network and LAN are interconnected by, e.g., one or more switches, has been accomplished by emulating the LAN in the ATM network so that, from the perspective of the nodes, the ATM network is transparent. This service is known in the data networking industry as LAN Emulation (LE) service over ATM. LE service supports the interconnection of ATM networks and LANs using traditional bridging methods and allows interoperability between applications on nodes, whether the nodes are connected to an ATM network or LAN.
FIG. 1
provides an example of a data network
100
comprising, e.g., an IEEE 802.3 LAN
120
and
130
interconnected via an ATM network
110
. Connected via segment
160
to the ATM network
110
is an ATM-based node
170
. Respectively connected to LANs
120
and
130
are LAN-based nodes
140
and
150
. With LE service, node
140
can communicate with node
170
or
150
utilizing the IEEE 802.2 LLC, network and transport layer protocols that it would otherwise use in a strictly LAN environment.
LE service is provided for by one or more LAN Emulation (LE) Clients (LECs) and a LAN Emulation (LE) service comprising an LE Configuration Server (LECS), LE Server (LES), and a Broadcast and Unknown Server (BUS). Generally speaking, the LECS assigns LE clients to a particular emulated LAN, while the LES registers and resolves MAC addresses or source route descriptors to ATM addresses, and the BUS handles multicast packets and unicast packets with an unknown destination address.
An LE Client is an ATM node such as a switch or node identified by one or more Media Access Control (MAC) addresses. The LE Service may be centralized or distributed across a number of devices such as an ATM node or switch. LECs communicate with the LES via control or data Virtual Circuit Connections (VCCs). The VCCs may be either Switched Virtual Circuits (SVCs) or Permanent Virtual Circuits (PVCs). For example, if the data network
100
of
FIG. 2
supported LE service, switches
210
and
230
may well operate as LECs, while switch
220
may perform the function of the LES.
Communication between LECs and the LES is defined according to the LAN Emulation User to Network Interface (LUNI). LUNI provides for, among other things, initialization of LE Clients, registration of MAC addresses represented by the LECs, ATM to MAC Address Resolution Protocol (LE-ARP), and transferring data from an LE Client to another LE Client as part of the LE service.
A LEC has a separate VCC for transmission of control packets such as LE-ARP packets and for data packets such as IEEE 802.3 frames. Thus, at least one separate VCC exists between the LEC and each component of the LES, namely, the LECS, the LEC, and the BUS, and in fact, in some instances, two VCCs exist between the LEC and LES component. Given communication occurring between two nodes in the network
100
, multiple control packets must be transmitted between the LEC and LES as well as the data packet(s) transmitted between the nodes. What is needed is a method and apparatus by which nodes in a network utilizing LE service may communicate more efficiently, without the need for transmission of multiple control packets between a LEC representing a particular node and the LES. Moreover, such method and apparatus may be applicable to any switched network environment.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an improved method and apparatus by which nodes may transmit data packets over a fully meshed network topology of permanently interconnected switches. A source node may transmit a data packet to a destination node across interconnected switches whereby a switch, upon receiving the data packet from the source node, queries other switches in the network for the appropriate switch and port on the switch out which to forward the data packet to the destination node. The appropriate switch responds to the query with its switch number and the port number of the port out which the data packet should be sent to reach the destination node. The querying switch caches the switch number and port number and prepends such information in the form of a destination tag to subsequent data packets it receives which are destined to the same destination node, thereby providing a distributed system among the switches in the network for maintaining detailed information regarding the appropriate switch and port out which to forward data packets received by a source node in the network.
REFERENCES:
patent: 5287535 (1994-02-01), Sakegawa
patent: 5408469 (1995-04-01), Opher et al
patent: 5420858 (1995-05-01), Marshall et al.
patent: 5425026 (1995-06-01), Mori
patent: 5432777 (1995-07-01), Le Boudec
patent: 5440547 (1995-08-01), Easki
patent: 5473603 (1995-12-01), Iwata
patent: 5583862 (1996-12-01), Callon
patent: 5617421 (1997-04-01), Chin et al.
patent: 5737334 (1998-04-01), Prince et al.
patent: 5742604 (1998-04-01), Edsall
patent: 5774662 (1998-06-01), Sakagawa
patent: 5802054 (1998-09-01), Bellenger
patent: 5825772 (1998-10-01), Dobbins et al.
patent: 6055561 (2000-04-01), Feldman
“LAN Emulation Over ATM Specification—Version1 1.0,” ATM-FORUM, LAN Emulation SWG Drafting Group, pp. 1-139.
Ferguson Earl
Goguen Michael L.
Johnson Bobby
Yip Michael
Blakely , Sokoloff, Taylor & Zafman LLP
Chin Wellington
Nguyen Steven
Nortel Networks Limited
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