Spanning tree bridge and route change method using the same

• US 20010021177A1
• Filed: 03/05/2001
• Published: 09/13/2001
• Est. Priority Date: 03/10/2000
• Status: Active Grant

• Current Assignee: Anritsu Corporation
• Original Assignee: Anritsu Corporation
• Inventors: Ishii, Shoji
• Granted Patent: US 6,891,808 B2
• Time in Patent Office: Days
• US Class Current: 370/256
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery

Abstract

A controller changes a blocked port to a forwarding state when a link down or change of the representative bridge is detected and a receiving port of a bridge settled in the root bridge is a blocked port. When the bridge itself is not settled in a root bridge, a transmitter transmits to another bridge a TCN-BPDU that, when the bridge itself has received a BPDU inferior to itself BPDU, the representative bridge changes. A transmitter transmits to all other bridges a TC detection flag set BPDU when the bridge itself has received a TCN-BPDU and the bridge itself is settled in a root bridge. When the bridge itself is not settled in a root bridge and the bridge itself has received the TC detection flag set BPDU, such BPDU is transmitted in a direction other than root bridge direction, and the contents of a forwarding table of the bridge itself are deleted.

Claims

1. A spanning tree bridge having the same algorithm and protocol each other, one of which is employed in a network containing a redundant route caused by a plurality of bridges settled in a root bridge, the spanning tree bridge comprising:

first detection means for detecting a link down of a root port that provides a shortest route to said root bridge;

second detection means for detecting a change of a representative bridge of a receiving port from information on Configuration Bridge Protocol Data Units (hereinafter, referred to as a BPDU) received from another bridge;

means for, when the first detection means detects a link down of the route port, settling the spanning tree bridge itself in a root bridge;

means for, in the case where a receiving port of spanning tree bridge settled in the root bridge is a blocked port, when the first detection means detects a link down of the root port or when the second detection means detects a change of the representative bridge, changing the blocked port to a forwarding state;

means for, in the case where the spanning tree bridge itself is not settled in a root bridge, when the spanning tree bridge that is not settled in the root bridge receives a BPDU from a representative port of a representative bridge of a received port inferior to its own BPDU, transmitting to the other bridge a Topology Change Notification BPDU (hereinafter, referred to as a TCN-BPDU) that the representative bridge changes;

means for, in the case where the spanning tree bridge itself is settled in a root bridge, when the spanning tree bridge itself settled in the root bridge receives a TCN-BPDU from another bridge, transmitting to all other bridges a BPDU in which Topology Change (hereinafter, referred to TC) detection flag is set; and

means for, in the case where the spanning tree bridge itself is not settled in a root bridge, the spanning tree bridge itself that is not settled in the root bridge receives a BPDU in which the TC detection flag is set, transmitting the BPDU in a direction other than root bridge direction, and deleting the content of a forwarding table of the spanning tree bridge itself that is not settled in the root bridge.

2. A spanning tree bridge having the same algorithm and protocol each other, one of which is employed in a network containing a redundant route caused by a plurality of bridges settled in a root bridge, the spanning tree bridge comprising:

first detection means for detecting a link down of a root port that provides a shortest route to said root bridge;

second detection means for detecting a change of a representative bridge of a receiving port from information on Configuration Bridge Protocol Data Units (hereinafter, referred to as a BPDU) received from another bridge;

means for, when the first detection means detects a link down of the route port or when the second detection means detects a change of the representative bridge, settling the spanning tree bridge itself in a root bridge;

means for, in the case where a receiving port of spanning tree bridge settled in the root bridge is a blocked port, when the first detection means detects a link down of the root port or when the second detection means detects a change of the representative bridge, changing the blocked port to a forwarding state;

means for, in the case where the spanning tree bridge itself is not settled in a root bridge, when the spanning tree bridge that is not settled in the root bridge receives a BPDU from a representative port of a representative bridge of a received port inferior to its own BPDU, transmitting to the other bridge a Topology Change Notification BPDU (hereinafter, referred to as a TCN-BPDU) that the representative bridge changes;

means for, in the case where the spanning tree bridge itself is settled in a root bridge, when the spanning tree bridge itself settled in the root bridge receives a TCN-BPDU from another bridge, transmitting to all other bridges a BPDU in which Topology Change (hereinafter, referred to TC) detection flag is set; and

means for, in the case where the spanning tree bridge itself is not settled in a root bridge, the spanning tree bridge itself that is not settled in the root bridge receives a BPDU in which the TC detection flag is set, transmitting the BPDU in a direction other than root bridge direction, and deleting the content of a forwarding table of the spanning tree bridge itself that is not settled in the root bridge.

3. A spanning tree bridge according to

claim 2

, further comprising means for, when the second detection means detects a change of the representative bridge, and when the spanning tree bridge settled in a root bridge receives a BPDU from another bridge superior to its own BPDU, setting the spanning tree bridge itself free of being settled in the root bridge.

4. A spanning tree bridge according to

claim 2

, further comprising means for, when the second detection means detects a change of the representative bridge, in the case where a port which has detected a change of the representative bridge is a root port, settling the spanning tree bridge itself in a root bridge, and in the case where a port which has detected a change of the representative bridge is not a root port, setting the spanning tree bridge free of being settled in the root bridge.

5. A spanning tree bridge route change method having the same algorithm and protocol each other, one of which is employed in a network containing a redundant route caused by a plurality of bridges settled in a root bridge, the method comprising the steps of:

detecting a link down of a root port that provides a shortest route to the root bridge;

detecting a change of a representative bridge of a receiving port from information on Configuration Bridge Protocol Data Units (hereinafter, referred to as a BPDU);

when a link down of the root port is detected, settling the spanning tree bridge itself in a root bridge;

in the case where a receiving port for a spanning tree bridge settled in the root bridge is a blocked port, when a link down of the root port is detected, changing the blocked port to a forwarding state;

in the case where the spanning tree bridge itself is not settled in a root bridge, when the spanning tree bridge itself that is not settled in the root bridge receives a BPDU a representative port of a representative bridge of a received port bridge inferior to its own BPDU, transmitting to the other bridge a Topology Change Notification BPDU (hereinafter, referred to as a TCN-BPDU) that the representative bridge changes;

in the case where the spanning tree bridge itself is settled in a root bridge, when the spanning tree bridge itself settled in the root bridge receives a TCN-BPDU from another bridge, transmitting to all other bridges a BPDU in which a Topology Change (hereinafter, referred to as a TC) detection flag is set; and

in the case where the spanning tree bridge itself is not settled in a spanning tree, when the spanning tree bridge itself that is not settled in the root bridge receives a BPDU in which the TC detection flag is set, transmitting the BPDU in a direction other than root bridge direction, and deleting the content of a forwarding table of the spanning tree bridge itself that is not settled in the root bridge.

6. A spanning tree bridge route change method having the same algorithm and protocol each other, one of which is employed in a network containing a redundant route caused by a plurality of bridges settled in a root bridge, the method comprising the steps of:

detecting a link down of a root port that provides a shortest route to the root bridge;

detecting a change of a representative bridge of a receiving port from information on Configuration Bridge Protocol Data Units (hereinafter, referred to as a BPDU);

when a link down of the root port is detected or when a change of the representative bridge is detected, settling the spanning tree bridge itself in a root bridge;

in the case where a receiving port for a spanning tree bridge settled in the root bridge is a blocked port, when a link down of the root port is detected, changing the blocked port to a forwarding state;

in the case where the spanning tree bridge itself is not settled in a root bridge, when the spanning tree bridge itself that is not settled in the root bridge receives a BPDU a representative port of a representative bridge of a received port bridge inferior to its own BPDU, transmitting to the other bridge a Topology Change Notification BPDU (hereinafter, referred to as a TCN-BPDU) that the representative bridge changes;

in the case where the spanning tree bridge itself is settled in a root bridge, when the spanning tree bridge itself settled in the root bridge receives a TCN-BPDU from another bridge, transmitting to all other bridges a BPDU in which a Topology Change (hereinafter, referred to as a TC) detection flag is set; and

in the case where the spanning tree bridge itself is not settled in a spanning tree, when the spanning tree bridge itself that is not settled in the root bridge receives a BPDU in which the TC detection flag is set, transmitting the BPDU in a direction other than root bridge direction, and deleting the content of a forwarding table of the spanning tree bridge itself that is not settled in the root bridge.

7. A spanning tree bridge route change method according to

claim 6

, the route change method comprising the step of:

when a change of the representative bridge is detected, when the spanning tree bridge itself settled in a root bridge receives a BPDU from another bridge superior to its own BPDU, setting the spanning tree bridge itself free of being settled in the root bridge.

8. A spanning tree bridge route change method according to

claim 6

, the route change method further comprising the step of:

when a change of the representative bridge is detected, in the case where a port which has detected a change of the representative bridge is a root port, settling the spanning tree bridge itself in a root bridge, and in the case where a port which has detected a change of the representative bridge is not a root port, setting the spanning tree bridge itself free of being settled in the root bridge.