Packet-content based WRED protection
A network element includes multiple ports and logic. The multiple ports are configured to serve as ingress ports and egress ports for receiving and transmitting packets from and to a network. The logic is configured to queue the packets received from the ingress ports, run a packet-dropping process that randomly drops one or more of the queued packets to avoid congestion, while detecting and excluding from the packet-dropping process, at least probabilistically, packets belonging to a predefined packet type, and forward the queued packets, which were not dropped, to the egress ports.
1. A network element, comprising:
multiple ports, configured to serve as ingress ports and egress ports for receiving and transmitting packets from and to a network;
a buffer which queues the packets received from the ingress ports;
a weighted random early detection (WRED) system which is configured to determine when a fill level of the buffer requires random packet dropping to avoid congestion, to determine first flows from which packets are to be dropped when random packet dropping is required, to drop packets which are not TCP-SYN or TCP-FIN packets from the first flows in accordance with a first dropping probability and to drop TCP-SYN packets of the first flows with a second dropping probability lower than the first dropping probability; and
a forwarding system which forwards the queued packets, which were not dropped, to the egress ports.
2. The network element according to claim 1 , wherein the second dropping probability is zero.
3. The network element according to claim 1 , wherein the second dropping probability is not zero.
4. The network element according to claim 1 , wherein the packet-dropping is performed in accordance with a Weighted Random Early Detection (WRED) process.
5. The network element according to claim 1 , wherein the WRED system is configured to drop TCP-FIN packets of the first flows when performing the random packet-dropping, with a probability lower than the first dropping probability.
6. The network element according to claim 1 , wherein the WRED system is also configured to detect and exclude from the packet-dropping process, at least probabilistically, packets that belong to flows that do not cause congestion.
7. The network element according to claim 1 , wherein the WRED system is also configured to detect and exclude from the packet-dropping, at least probabilistically, packets that belong to flows having less than a predefined number of packets.
8. The network element according to claim 1 , wherein the network element is configured to modify the second dropping probability based on traffic analysis.
9. A method, comprising:
in a network element, receiving and transmitting packets from and to a network using multiple ports that serve as ingress and egress ports;
queuing packets received from the ingress ports in a buffer;
when a fill level of the buffer requires random packet dropping to avoid congestion, determining first flows from which packets are to be dropped and dropping packets which are not TCP-SYN or TCP-FIN packets from the first flows in accordance with a first dropping probability and dropping TCP-SYN packets of the first flows with a second dropping probability lower than the first dropping probability;
forwarding the queued packets, which were not dropped, to the egress ports.
10. The method according to claim 9 , wherein second dropping probability is zero.
11. The method according to claim 9 , wherein second dropping probability is not zero.
12. The method according to claim 9 , wherein the packet-dropping is performed in accordance with a Weighted Random Early Detection (WRED) process.
13. The method according to claim 9 , further comprising dropping TCP-FIN packets of the first flows when performing the random packet-dropping, with a probability lower than the first dropping probability.
14. The method according to claim 9 , wherein determining first flows from which packets are to be dropped comprises detecting and excluding from the packet-dropping packets that belong to flows that do not cause congestion.
15. The method according to claim 9 , wherein determining first flows from which packets are to be dropped comprises detecting and excluding from the packet-dropping process packets that belong to flows having less than a predefined number of packets.