Detecting loops between network devices by monitoring MAC moves
View Patent ↗A technique for detecting a loop between network devices such as customer and carrier edge devices involves counting the number of media access control (MAC) address moves that occur at a device and comparing the number of MAC address moves to a pre-established MAC move threshold. The technique includes artificially accelerating the MAC move count related to a MAC address when the MAC address is moving between a set of ports at which the MAC address was previously found. The MAC move count is artificially accelerated because movement of a MAC address between a set of ports at which the MAC address was previously found is a strong indication of loop. The MAC move count is artificially accelerated by weighting the MAC move count once it has been determined that a MAC is moving between a set of ports at which the MAC address was previously found.
1. A method for detecting a loop between network devices comprising:
establishing a media access control (MAC) move threshold;
counting the number of times a MAC address moves between ports of a network device to obtain a MAC move count;
determining if the MAC address has moved to a port at which the MAC address was previously found;
if the MAC address has moved to a port at which the MAC address was previously found, weighting the MAC move count;
comparing the MAC move count to the MAC move threshold; and
concluding that a loop exists if the MAC move count exceeds the MAC move threshold.
2. The method of claim 1 wherein determining if the MAC address has moved to a port at which the MAC address was previously found comprises maintaining a record of a set of ports at which the MAC address was previously found.
3. The method of claim 2 further comprising limiting the set of ports to a maximum number.
4. The method of claim 1 wherein loops are detected on a per-broadcast domain basis.
5. The method of claim 1 wherein weighting the MAC move count comprises exponentially weighting the MAC move count.
6. The method of claim 1 wherein weighting the MAC move count comprises linearly weighting the MAC move count.
7. The method of claim 1 wherein the MAC move count is weighted as a function of the MAC move count.
8. The method of claim 1 wherein weighting the MAC move count comprises weighting the MAC move count as a function the MAC address, wherein the MAC address is a source MAC address.
9. The method of claim 1 wherein establishing the MAC move threshold includes identifying a number of MAC moves per unit of time.
10. The method of claim 1 further comprising initiating a loop protection action if it is concluded that a loop exists.
11. A method for detecting loops between a customer network and a carrier network comprising:
establishing a media access control (MAC) move threshold;
monitoring moves of a MAC address between ports of a carrier device that are caused by customer traffic from a customer network to determine a MAC move count, the carrier device being in a carrier network that receives traffic from the customer network;
determining if the MAC address has moved to a port at which the MAC address was previously found;
if the MAC address has moved to a port at which the MAC address was previously found, weighting the MAC move count;
at the carrier device, comparing the MAC move count to the MAC move threshold; and
concluding that a loop exists if the MAC move count exceeds the MAC move threshold.
12. The method of claim 11 wherein determining if the MAC address has moved to a port at which the MAC address was previously found comprises maintaining a record of a set of ports at which the MAC address was previously found.
13. The method of claim 12 further comprising limiting the set of ports to a maximum number.
14. The method of claim 11 wherein loops are detected on a per-broadcast domain basis.
15. The method of claim 11 wherein the MAC move count is weighted as a function of the MAC move count.
16. The method of claim 11 wherein weighting the MAC move count comprises weighting the MAC move count as a function of the MAC address, wherein the MAC address is source MAC address.
17. The method of claim 11 further comprising initiating a loop protection action at the carrier device if the rate of MAC moves exceeds the MAC move threshold.
18. A system for detecting loops between a customer network and a carrier network comprising:
a loop management engine configured to:
establish a media access control (MAC) move threshold;
count the number of times a MAC address moves between ports of a network device to obtain a MAC move count;
determine if the MAC address has moved to a port at which the MAC address was previously found;
if the MAC address has moved to a port at which the MAC address was previously found, weight the MAC move count;
compare the MAC move count to the MAC move threshold; and
conclude that a loop exists if the MAC move count exceeds the MAC move threshold.
19. The system of claim 18 wherein the loop management engine is configured to maintain a record of a set of ports at which the MAC address was previously found.
20. The system of claim 18 wherein the set of ports is limited to a maximum number.