Storm Control
Understanding of storm control
Storm control to prevent the switch port is the LAN broadcast, multicast, or a physical port unicast storm damage. Turmoil in the local area network packets flooding in the local area network, the establishment of the excessive traffic and the loss of network performance. Errors in the protocol stack or network configuration errors can lead to turmoil.
Storm control (or called traffic suppression) the management of the flow into the stack, and through a period of time and comparing the measurement with the suppression of pre-set threshold level approach to management. Performance threshold for the port in general the percentage of available bandwidth. Switches to support the separate storm control threshold for multicast and unicast radio. If the flow type to reach the threshold, more of this type would be to suppress the flow until the flow into the stack dropped to below threshold level.
Note: When the multicast group in excess of the speed threshold, all the stops traffic (unicast multicast broadcast) will be discarded until the level dropped to below the threshold level. Stp will only be forwarded the packet. When broadcast and unicast when threshold exceeded, only the flow beyond the threshold will be sealed off.
When the storm control opens, the switch to monitor the packet through the interface bus and decided to exchange the packet is unicast, multicast or broadcast. Multicast and broadcast switches to monitor the number of unicast, each 1 second time, and when a certain type of traffic to reach the threshold, the traffic will be discarded. This threshold can be broadcast to the general use of the percentage of available bandwidth has been designated.
The following is an interface on the radio for some time flow curve of the model.
This example can also be multicast and unicast traffic apply. In this example, the radio traffic in the T1-T2, T4-T5 has been transmitted over time between the configuration of the threshold of all kinds of traffic are discarded the next time. Therefore broadcast traffic in the time T2 and T5 are closed. When the next break, T3, if broadcast traffic does not exceed the limit, then it was transmitted.
Storm control algorithm is inhibited storm control interval level and a second combination of control. A higher threshold allows more packets through. If the door threshold set to 100% means that all will not be any traffic restrictions. 0% means that all of the broadcast multicast and unicast traffic will be closed.
Note: because the packages do not arrive at uniform time interval, second interval between the absence of flow control will affect the storm.
Continue to monitor the switch port traffic, and when the use of threshold-level down to the following, which type of traffic being discarded, will be re-transmitted.
You can use the storm-control interface command to set the threshold for each type of flow.
Storm control the default configuration:
By default, the broadcast multicast unicast storm control are in the closed switch means that: suppression level is 100%
Open storm control:
You open the storm control interface, and enter the percentage of the total available bandwidth to be used to identify you to the kinds of traffic; 100% will allow the importation of all traffic. However, because of hardware limitations, as well as different package sizes will lead to deviation of the percentage threshold is an approximation.
Note: storm control only supports the use of physical ports; it does not support the use of Ethernet access, although able to get out.
The following examples f0/17 multicast storm under the 70.5% limit
Switch # configure terminal
Switch (config) # interface fastethernet0/17
Switch (config-if) # storm-control multicast level 70.5
Switch (config-if) # end
Switch # show storm-control fastethernet0/17 multicast
Interface Filter State Level Current
——— ————- ——- ——-
Fa0/17 Forwarding 70.50% 0.00%
This is a closed storm control
Switch # configure terminal
Switch (config) # interface fastethernet0/17
Switch (config-if) # no storm-control multicast level
Switch (config-if) # end
Switch # show storm-control fastethernet0/17 multicast
Interface Filter State Level Current
——— ————- ——- ——-