US 5,331,634 AGranted

Technique for bridging local area networks having non-unique node addresses

AssigneeDigital Ocean, Inc.

InventorMichael A. Fischer

Life of this patent

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Abstract

A bridging apparatus provides the capability of transparently and unambiguously communicating LAN packets between two separate LAN segments which have nodes with duplicate IDs. A communicator connected to each LAN segment includes a controller which aliases the source identification (SID) of remotely originated or sourced LAN packets with an unused ID which is an alias (AID) before sending the LAN packet with the AID as its SID on the local LAN segment. The reverse occurs in response to locally sourced LAN packets containing the AID as the DID. The ID of the remote node which correlates to the AID is substituted as the DID before the LAN packet is transmitted to the remote LAN segment. By aliasing in this manner LAN packets are communicated by use of the AIDs between the nodes having the duplicate IDs on the two LAN segments without changing the LAN protocol. Each communicator preferably includes a transmitter and receiver by which to communicate bridge packets between communicators. The LAN packets are encapsulated in the bridge packets. Unique communicator source and destination identifications are included in each bridge packet to form a tuple which uniquely identifies each node in the Group without regard to the duplicate IDs on the separate LAN segments.

Claims38

Dependent claims

Bridging apparatus for communicating LAN packets between at least two separate LAN segments in which at least one node of a local LAN segment has a duplicate identification (ID) of a node of at least one other remote LAN segment, comprising:

LAN interface means adapted to be connected to each LAN segment and operative for communicating LAN packets with the nodes of the connected LAN segment using a LAN protocol, the LAN protocol prohibiting nodes with the same ID only on each LAN segment, the LAN protocol further requiring a source ID (SID) and a destination ID (DID) to be included in each LAN packet to identify a source node sending the LAN packet and a destination node receiving the LAN packet respectively, each LAN packet being one of either a locally destined LAN packet sent by a source node on a local LAN segment and destined for a destination node on the same local LAN segment or a remotely destined LAN packet sent by a source node on one LAN segment and destined for a destination node on a different and remote LAN segment;
and
interoperative bridging means operatively connected to and controlling the LAN interface means, the interoperative bridging means functioning in response to a remotely destined LAN packet to communicate the remotely destined LAN packet to the remote LAN segment, the interoperative bridging means further including aliasing means;
the aliasing means responding to the SID of a remotely destined LAN packet received from one LAN segment and determining if the SID is a duplicate of an ID in use on the other LAN segment and if so substituting for the SID an unused ID on the other LAN segment as an alias ID (AID) before sending the LAN packet with the AID as the SID on the other LAN segment, and
the aliasing means communicating LAN packets by use of the AID between the nodes having the duplicate IDs on the LAN segments without changing the LAN protocol.

2 more elements

A bridging method for communicating LAN packets between at least two separate LAN segments in which at least one node of a local LAN segment has a duplicate identification (ID) of a node of at least one other remote LAN segment, comprising the steps of:

connecting a LAN interface to each LAN segment;
communicating LAN packets with the nodes of the connected LAN segment using the connected LAN interface operating in accordance with a LAN protocol;
prohibiting nodes with the same ID only on each LAN segment in accordance with the LAN protocol;
including a source ID (SID) and a destination ID (DID) in each LAN packet to identify a source node sending the LAN packet and a destination node receiving the LAN packet respectively, in accordance with the LAN protocol;
designating each LAN packet as one of either a locally destined LAN packet sent by a source node on a local LAN segment and destined for a destination node on the same local LAN segment or a remotely destined LAN packet by a source node on one LAN segment and destined for a destination node on a different and remote LAN segment;
and
communicating a remotely destined LAN packet from a local LAN segment to a remote LAN segment by steps including:
determining if the SID of the remotely destined LAN packet received form one LAN segment is a duplicate of an ID in use on the other LAN segment, and if so
substituting for the SID an unused ID on the other LAN segment as an alias ID (AID) for the SID of the remotely destined LAN packet before communicating the LAN packet with the AID as the SID to the other LAN segment, and
communicating LAN packets by use of the AID between the nodes having the duplicate IDs on the LAN segments without changing the LAN protocol.

7 more elements

Dependencies are inferred from the claim text.