Utilization of redundant links in bridged networks
First Claim
1. In a bridged communication network that has been pruned to form a loop-free spanning tree configuration having a root bridge, a method of exchanging messages between stations, through a point-to-point cross-link outside the spanning tree configuration, the method comprising the steps of:
- identifying a cross-link between any two bridges in the network, wherein the cross-link exists outside the spanning tree configuration;
selecting in at least one of the two bridges a set of destination stations for receipt of messages to be transmitted over the cross-link, the destination stations being selected without regard to their locations with respect to the root bridge in the spanning tree configuration;
advising the other of the two bridges of the identities of the selected destination stations;
examining each message received over the spanning tree at the other of the two bridges to determine if the intended destination of the message qualifies as one of the selected stations; and
forwarding the message over the cross-link if the destination station in the message qualifies.
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Accused Products
Abstract
A method and related apparatus for establishing a point-to-point cross-link between two bridges in a bridged communication network. The bridged communication network is first configured in a loop-free arrangement by a spanning tree algorithm that selects which links of every bridge to activate in order to form the spanning tree active configuration. Then at least one cross-link not defined by the spanning tree configuration is established for routing of messages as an alternative to a spanning tree path. A protocol in each bridge ensures that no loops are formed and that only messages to preselected locations are passed over the cross-link. An optional optimization procedure measures message propagation times in both directions between the two bridges and over both the cross-link path and the spanning tree path, to determine whether to modify usage of the cross-link. Selection of the bridges for the formation of the cross-link, and selection of the destination stations for cross-link traffic, are independent of the location of a root bridge in the spanning tree configuration.
133 Citations
28 Claims
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1. In a bridged communication network that has been pruned to form a loop-free spanning tree configuration having a root bridge, a method of exchanging messages between stations, through a point-to-point cross-link outside the spanning tree configuration, the method comprising the steps of:
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identifying a cross-link between any two bridges in the network, wherein the cross-link exists outside the spanning tree configuration; selecting in at least one of the two bridges a set of destination stations for receipt of messages to be transmitted over the cross-link, the destination stations being selected without regard to their locations with respect to the root bridge in the spanning tree configuration; advising the other of the two bridges of the identities of the selected destination stations; examining each message received over the spanning tree at the other of the two bridges to determine if the intended destination of the message qualifies as one of the selected stations; and forwarding the message over the cross-link if the destination station in the message qualifies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. For use in a bridged communication network that has been pruned to form a loop-free spanning tree configuration having a root bridge, a method of establishing and using a cross-link between two bridges, such that the cross-link is not in the spanning tree configuration, the method comprising the steps of:
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transmitting a cross-link greeting message from each bridge in the network having inactive links no included in the spanning tree configuration, the cross-link greeting message being transmitted along each of the inactive links and containing the identity of the bridge transmitting the message; receiving a cross-link greeting message in at least one bridge that transmitted such a message, wherein the existence of at least one cross-link between two bridges is established and each bridge is made aware of the identity of the other; identifying at each of the two bridges a spanning tree link through which communication can take place with the other of the two bridges over the spanning tree; selecting at each of the two bridges a set of destination stations for receipt of messages to be transmitted over the cross-link, wherein the stations are selected without regard to their locations relative to the root bridge of the spanning tree configuration, and wherein each selected station is not reached through the spanning tree link leading to the other bridge; advising the other of the two bridges of the identities of the selected destination stations; examining each message received over the spanning tree at each of the two bridges to determine if the intended destination of the message qualifies as one of the destination stations selected by the other of the bridges; forwarding the message over the cross-link if the destination station in the message qualifies; examining each message received through the cross-link at each of the two bridges to determine that the message contains a valid destination address; and forwarding the message toward its destination station if the destination address qualifies. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. In a bridged communication network that has been pruned to form a loop-free spanning tree configuration having a root bridge, apparatus for exchanging messages between stations, through a point-to-point cross-link outside the spanning tree configuration, the apparatus comprising:
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means for identifying a cross-link between any two bridges in the network, wherein the cross-link exists outside the spanning tree configuration; means for selecting at each of the two bridges a set of destination stations for receipt of messages to be transmitted over the cross-link, the destination stations being selected without regard to their locations with respect to the root bridge in the spanning tree configuration; means for advising the other of the two bridges of the identities of the selected destination stations; means for examining each message received over the spanning tree at each of the two bridges to determine if the intended destination of the message qualifies as one of the destination stations selected by the other of the bridges; and means for forwarding the message over the cross-link if the destination station in the message qualifies. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification