Establishing shortcuts in a Multiprotocol-over-ATM system

Multiplex communications – Pathfinding or routing – Switching a message which includes an address header

Reexamination Certificate

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Details

C370S401000

Reexamination Certificate

active

06671279

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to communication networks, and, more particularly, to selectively establishing shortcuts in a Multiprotocol-over-ATM (MPOA) system based upon an MPOA server response time.
BACKGROUND OF THE INVENTION
In today's information age, communication devices typically support a number of different protocols that enable the communication devices to communicate over a data communication network. These various protocols are typically organized in layers, such that the protocol at a particular layer of the protocol stack provides communication services to the higher layer protocols and receives communication services from the lower layer protocols.
In order for the data communication network to be efficient, the data communication network is often divided into subnetworks. Communication devices within the same subnetwork communicate over a Local Area Network (LAN) using a LAN protocol, such as Ethernet or Token Ring, at a medium access control (MAC) protocol layer of the protocol stack. Communication devices on different subnetworks communicate using an internetwork protocol, such as the Internet Protocol (IP), IPX, or Appletalk; that requires routing at the internetwork protocol layer of the protocol stack. For convenience, a communication device that provides routing functions at the internetwork protocol layer of the protocol stack is commonly referred to as a “router.”
With the advent of Asynchronous Transfer Mode (ATM) networks, it was desirable to allow communication devices to be internetworked over the ATM network, and specifically over Virtual Channel Connections (VCCs) in the ATM network, in much the same was as those communication devices were internetworked over the LAN. Therefore, a LAN Emulation procedure was defined to allow such communication devices to be internetworked over the ATM network. LAN Emulation enabled those communication devices within the same subnetwork to communicate as if those communication devices were internetworked over the LAN. However, communication between communication devices on different subnetworks still required routing at the internetwork protocol layer of the protocol stack.
Therefore, certain protocols were defined to allow communication devices on different subnetworks to communicate without requiring routing at the internetwork protocol layer of the protocol stack (or at least without requiring routing along the entire data path). One such protocol, known as Multiprotocol-over-ATM (MPOA), is described in an ATM Forum Technical Committee document entitled
Multi
Protocol Over ATM Version 1.0, document number AF-MPOA-0087.000 (July 1997), incorporated herein by reference in its entirety (referred to hereinafter as the “MPOA specification”). MPOA allows communication devices to communicate in an ELAN environment without requiring routing through the ELAN at the internetwork protocol layer of the protocol stack. Specifically, MPOA allows those communication devices at the edge of the ELAN to establish a shortcut VCC through the ATM network and forward the inter-subnetwork data traffic over the shortcut VCC rather than route the inter-subnetwork data traffic at the internetwork protocol layer of the protocol stack.
The present invention relates to the establishment of shortcut VCCs in an MPOA network.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, a technique for establishing a shortcut Virtual Channel Connection (VCC) in a Multi-Protocol Over ATM (MPOA) system involves receiving packets, detecting a packet flow, determining that an expected MPOA server response time is within a predetermined MPOA server response time threshold, and establishing the shortcut. In various embodiments of the present invention, the packet flow is detected using a packet flow rate filter and/or a verification table filter.
In accordance with another aspect of the invention, a technique for establishing a shortcut VCC in an MPOA system involves receiving packets, detecting a packet flow, determining an expected MPOA server response time based upon MPOA server response time information stored in an MPOA server response time history, comparing the expected MPOA server response time to a predetermined MPOA server response time threshold to determine whether the expected MPOA server response time is within the predetermined MPOA server response time threshold, determining that the expected MPOA server response time is within the predetermined MPOA server response time threshold, and establishing the shortcut VCC. Upon establishing the shortcut VCC, the MPOA server response time information stored in the MPOA server response time history is updated to reflect an actual MPOA server response time incurred when establishing the shortcut VCC.
In accordance with yet another aspect of the invention, a technique for establishing a shortcut VCC in an MPOA system involves receiving packets, detecting a packet flow, determining an expected MPOA server response time based upon MPOA server response time information stored in an MPOA server response time history, determining an MPOA server response time threshold using a resource filter, comparing the expected MPOA server response time to the predetermined MPOA server response time threshold to determine whether the expected MPOA server response time is within the predetermined MPOA server response time threshold, determining that the expected MPOA server response time is within the predetermined MPOA server response time threshold, and establishing the shortcut VCC. Upon establishing the shortcut VCC, the MPOA server response time information stored in the MPOA server response time history is updated to reflect an actual MPOA server response time incurred when establishing the shortcut VCC.


REFERENCES:
patent: 5774662 (1998-06-01), Sakagawa
patent: 5878043 (1999-03-01), Casey
patent: 6064675 (2000-05-01), Alexander, Jr. et al.
patent: 6081836 (2000-06-01), Karapetkov et al.
patent: 6125123 (2000-09-01), Furuno
patent: 6421321 (2002-07-01), Sakagawa et al.

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