US 7,453,818 B2 · Detection of potential forwarding loops in bridged networks

Abstract

Potential forwarding loops in bridged networks are detected. A switch monitors the movement of packet addresses in the forwarding table to different ports. If the port associated with an address changes multiple times in a short time duration, then a potential forwarding loop is detected, and a loop corrector is notified to take appropriate action to correct the problem, such as, but not limited to changing the state of a port to a blocking state or disabling an interface, etc. If there are multiple movements outside the short time duration, they may be correct movements adjusting to the actual reconfiguration of a network, and thus, these movements are effectively filtered out of consideration.

Claims26

Dependent claims

An apparatus configured to identify potential forwarding loops in a network, the apparatus comprising:

a plurality of packet receivers configured to receive packets, with each of said received packets including an address in the source address field in the header of said received packets identifying the source of the packet;
a forwarding data structure configured for storing associations of said addresses with particular packet receivers;
a network topology updater configured to perform Spanning Tree Protocol including sending of Hello messages at intervals of a predetermined Hello time and to update the forwarding data structure;
a moved data structure configured for storing addresses whose corresponding packet receiver has recently moved;
and
a loop detector configured to manage recently moved addresses using the moved data structure in order to identify a potential routing loop when a movement for a same address has occurred n times within a predefined time duration, with n being an integer of at least two, wherein the predefined time duration is less or equal to approximately twice the Hello time;
wherein the loop detector is configured to notify a loop corrector to respond to said identification of the potential routing loop.

4 more elements

A method performed by a networked packet switching device configured to identify potential forwarding loops in a network, the packet switching device including a plurality of packet receivers, a forwarding data structure configured for storing associations of addresses with packet receivers of the plurality of packet receivers;

and a moved data structure configured for storing addresses whose corresponding packet receiver of the plurality of packet receivers has recently moved, the method comprising:
repeatedly:
receiving and processing a new particular packet, the particular packet including a particular source address in the source address field in the header of the particular packet identifying the source of the packet;
wherein said processing the particular packet includes evaluating the forwarding data structure for the particular source address, and in response to an identification that a particular packet receiver of the plurality of packet receivers associated with the particular source address has moved from a prior particular packet receiver based on the forwarding data structure and the particular source address extracted from the particular packet, updating the moved data structure to reflect that the packet receiver associated with the particular source address has moved;
wherein the associated said one of the plurality of packet receivers is updated in the forwarding data structure for the particular source address at least when said move is detected;
and
periodically evaluating recently moved addresses in the moved data structure in order to identify a potential routing loop when a movement for a same address has occurred m times within a predefined time duration, with m being an integer of at least two;
and in response to said identification of the potential routing loop, notifying a loop corrector configured to respond to said identification of the potential routing loop.

5 more elements

An apparatus configured to identify potential forwarding loops in a network, the apparatus comprising:

a plurality of packet receivers;
a forwarding data structure configured for storing associations of addresses with packet receivers of the plurality of packet receivers;
a moved data structure configured for storing addresses whose corresponding packet receiver of the plurality of packet receivers has recently moved;
means for repeatedly processing a received new particular packet, the particular packet including a particular source address in the source address field in the header of the particular packet identifying the source of the packet;
wherein said processing the particular packet includes evaluating the forwarding data structure for the particular source address, and in response to an identification that a particular packet receiver of the plurality of packet receivers associated with the particular source address has moved from a prior particular packet receiver based on the forwarding data structure and the particular source address extracted from the particular packet, updating the moved data structure to reflect that the packet receiver associated with the particular source address has moved;
wherein the associated said one of the plurality of packet receivers is updated in the forwarding data structure for the particular source address at least when said move is detected;
and
means for identifying a potential routing loop when a movement for a same address has occurred in each of r consecutive time intervals and for notifying a loop corrector to respond to said identification of the potential routing loop, wherein r is an integer greater than one.

5 more elements

Dependencies are inferred from the claim text.

Detection of potential forwarding loops in bridged networks

Life of this patent

Detection of potential forwarding loops in bridged networks

Life of this patent

Abstract

Claims26