US 6,813,250 B1 · Shared spanning tree protocol

Abstract

A shared spanning tree protocol (SSTP) creates a plurality of spanning trees (i.e., loop-free paths) which are shared among one or more virtual local area network (VLAN) designations for data transmission within a computer network. Each shared spanning tree includes and is defined by a primary VLAN and may be associated with one or more secondary VLANs. In order to associate VLAN designation(s) with a single shared spanning tree, network devices exchange novel shared spanning tree protocol data units (SST-PDUs). Each SST-PDU corresponds to a given primary VLAN and preferably includes one or more fields which list the secondary VLAN designations associated with the given primary VLAN. The association of VLAN designations to shared spanning trees, moreover, preferably depends on which path traffic is to follow as well as the anticipated load characteristics of the various VLANs. The association of VLAN designations to shared spanning trees thus provides a degree of load balancing within the network. Data messages tagged with a particular VLAN designation are then distributed by the devices only along the shared spanning tree to which that VLAN has been associated by SSTP.

Claims20

Dependent claims

In a network device having a plurality of ports each associated with zero, one or more virtual local area network (VLAN) designations that are classified as either primary or secondary VLANs, a method for transitioning the ports among a plurality of spanning tree port states including a blocking state and a forwarding state, the method comprising the steps of:

generating bridge protocol data units (BPDUs) one or more of which are tagged with a given primary VLAN designation;
forwarding the tagged BPDUs from at least one port;
transitioning at least one port to the forwarding state for the given primary VLAN designation;
and
associating at least one secondary VLAN with the given primary VLAN.

2 more elements

A network device for use in a computer network having a plurality of virtual local area network (VLAN) designations, at least some of the VLAN designations being classified as either a primary VLAN designation or as a secondary VLAN designation wherein each secondary VLAN designation is associated with zero, one or more than one primary VLAN designations, the network device comprising:

means for receiving and sending messages from the network device;
means, coupled to the receiving and sending means, for generating and sending bridge protocol data units (BPDUs) tagged with a primary VLAN designation;
means, coupled to the receiving and sending means, for generating and sending shared spanning tree protocol data units (SST-PDUs) tagged with a VLAN designation and, where the VLAN tag of the SST-PDU corresponds to a primary VLAN to which one or more secondary VLANs are associated, the SST-PDU configured to contain at least one associated secondary VLAN designation;
and
means for associating secondary VLAN designations contained in received SST-PDUs with the primary VLAN designation with which the respective SST-PDUs are tagged.

2 more elements

Dependencies are inferred from the claim text.

Shared spanning tree protocol

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Shared spanning tree protocol

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Abstract

Claims20