Global policers

1. Apparatus for global traffic policing, comprising:

a network device comprising a local policer configured to perform for each of a plurality of flows:

store a maximum bandwidth for the flow,

monitor an amount of bandwidth of the flow passing through the network device, and

perform traffic policing on the flow within the network device at least in part by determining whether a current level bandwidth of the flow exceeds the stored maximum bandwidth for the flow; and

a communications module configured to:

send local policer state information, including the monitored amount of bandwidth passing through the network device, for each of the flows, from the local policer to a remote global policer; and

receive remote global policer state information, including the current level bandwidth of each of the flows, from the remote global policer and update the local policer state information based on the received remote global policer state information.

2. Apparatus according to claim 1 and wherein the network device comprises a switch.

3. Apparatus according to claim 1 and wherein the network device comprises a network interface controller (NIC).

4. Apparatus according to claim 1 and wherein:

the local policer comprises a plurality of local policers, each associated with one of the plurality of flows; and

the communications module is configured to:

send local policer state information from each local policer to a corresponding remote global policer; and

receive policer state information from each remote global policer and update the corresponding local policer state information based on the corresponding remote policer state information, the local policer state information comprising a traffic parameter associated with each of the plurality of local policers, for marking a received packet in order to determine, at least in part, whether said received packet should be dropped.

5. Apparatus according to claim 1 and wherein the traffic policing comprises dropping at least one incoming packet, which has been marked, associated with the flow.

6. Apparatus according to claim 4 and wherein the traffic parameter comprises a three color marker.

7. Apparatus for global traffic policing in a network, the apparatus comprising:

a network device comprising a global policer; and

a communications module configured to:

receive local policer state information from a plurality of local policers in other network devices in the network, wherein the received information includes a monitored amount of bandwidth passing through the network device, for each of a plurality of flows,

aggregate the received state information into a current level bandwidth of each of the flows, and

send policer state information, including the current level bandwidth, from the global policer to said plurality of local policers for updating local policer state information based on the global policer state information.

8. Apparatus according to claim 7 and wherein:

the communications module is configured to:

receive local policer state information from each local policer, and pass the received local policer state information to a corresponding global policer; and

send policer state information from each global policer to each said local policer for updating local policer state information based on the corresponding global policer state information, including a traffic parameter for updating each of the plurality of local policers, the traffic parameter for marking a received packet in order to determine, at least in part, whether said received packet should be dropped.

9. Apparatus according to claim 7 and wherein the global policer is configured, in performing said traffic policing on flows with a plurality of network devices:

to maintain a policing quota and a current level for each of said flows;

to adjust said current level based on said received local policer state information; and

to provide new policing quota information to said communications module as part of said policer state information.

10. Apparatus according to claim 8 and wherein the traffic parameter comprises a three color marker.

11. Apparatus according to claim 7 , wherein the global policer is configured to receive local policer state information from a pre-defined set of switches expected to forward packets to be monitored, wherein the pre-defined set of switches includes fewer than all leaf switches in the network.

12. A method for global traffic policing in which a communications module, associated with a network device comprising a local policer is configured to perform traffic policing on each flow of a plurality of flows, the method comprising the network device performing the following for each of a plurality of flows:

storing a maximum bandwidth for the flow;

monitoring an amount of bandwidth of the flow passing through the network device;

sending local policer state information, including the monitored amount of bandwidth of the flow passing through the network device, from the local policer to a remote global policer; and

receiving policer state information, including a current level bandwidth of the flow, from the remote global policer and updating the local policer state information based on the received remote global policer state information,

wherein the local policer performs traffic policing at least in part by determining whether the current level bandwidth of the flow exceeds the stored maximum bandwidth for the flow.

13. The method according to claim 12 and wherein the network device comprises a switch.

14. The method according to claim 12 and wherein the network device comprises a network interface controller (NIC).

15. The method according to claim 12 and wherein:

the local policer comprises a plurality of local policers, each associated with one of the plurality of flows; and

the communications module performs the following:

sends local policer state information from each local policer to a corresponding remote global policer; and

receives policer state information from each remote global policer and updates the corresponding local policer state information based on the corresponding remote policer state information, including a traffic parameter for updating each of the plurality of local policers, the traffic parameter for marking a received packet in order to determine, at least in part, whether said received packet should be dropped.

16. The method according to claim 12 and wherein the traffic policing comprises dropping at least one incoming packet, which has been marked, associated with the flow.

17. A method according to claim 15 and wherein the traffic parameter comprises a three color marker.

18. A method for global traffic policing in a network, comprising:

receiving, by a communications module of a global policer in a network device, local policer state information from a plurality of local policers comprised in other network devices in the network, wherein the received information includes a monitored amount of bandwidth passing through the network device, for each of a plurality of flows;

aggregating the received state information into a current level bandwidth of each of the flows, by the global policer, and

sending global policer state information, including the current level bandwidth, from the global policer to said plurality of local policers for updating local policer state information based on the global policer state information.

19. The method according to claim 18 and wherein:

the communications module performs the following:

receives local policer state information from each local policer, and passes the received local policer state information to a corresponding global policer; and

sends policer state information from each global policer to each said local policer for updating local policer state information based on the corresponding global policer state information, including a traffic parameter for updating each of the plurality of local policers, the traffic parameter for marking a received packet in order to determine, at least in part, whether said received packet should be dropped.

20. The method according to claim 18 and wherein the global policer, in performing said traffic policing on flows with a plurality of network devices:

maintains a policing quota and a current level for each of said flows;

adjusts said current level based on said received local policer state information; and

provides new policing quota information to said communications module as part of said policer state information.

21. A method according to claim 19 and wherein the traffic parameter comprises a three color marker.