Storm Control for Broadcast, Unknown Unicast, and Multicast Traffic

A broadcast, unknown unicast, and multicast (BUM) traffic storm occurs when packets flood the LAN, creating excessive traffic and degrading network performance.

Use BUM storm control to limit the amount of BUM ingress traffic globally or on a specified physical interface. All ingress traffic in excess of the configured rate is discarded.

Consider the following when you configure storm control:

BUM storm control applies only to ingress traffic.
The device supports both global and interface-level BUM storm control.
BUM storm control and input service-policy features can coexist on an interface.
It can only be configured on physical interfaces in SLX 9540, SLX 9640, SLX 9150 and SLX 9250.
For LAG ports, BUM RL needs to be attached to each LAG member port on SLX 9150, SLX 9250, SLX 9540 and SLX 9640.
On SLX 9740, BUM RL is applied directly on LAG. If there are multiple LAG members on one line card, the CIR on that Line card is limited to configured CIR. The CIR will not be applied per member port, but on the LAG. Hardware creates and maintains policer on each core separately, hence there will be Rate-limiting applied per core, and in case where Rate-limiting is done on Port Channel and there are Port-Channel members across cores / Units, we will see separate Rate-limiting applied. It is advisable to have the port Channel members to be part of the same core, to have uniform Rate-limiting.
A Single-rate Two Color Marking (SrTCM) scheme is used.
Metering is performed on the packet size as received on the wire, including IPG (inter-packet gap) and preamble, but ignoring CRC (cyclic redundancy check).
BUM rate limiting is ineffective if the BUM traffic is also classified by an ACL.
The configured rate in bits per second (bps) is rounded up to next achievable rate.
On SLX 9150 and 9250 only hit counters are supported, hence violated counters will not be updated.
In SLX 9540, 9640 and 9740 only FWD and DROP counters are supported.
- Conformed: Shows FWD packets including green and yellow color packets.
- ( SLX 9640 and SLX 9540 only) Violated: Shows DROP packets including red color packets.
- ( SLX 9640 and SLX 9540 only) Exceed: Is always ZERO.
In SLX 9540, 9640, FWD and DROP counters must use a counter profile other than default.
( SLX 9640 and SLX 9540 only) When storm control is configured at the interface level, you can specify whether to shut down an interface if the maximum defined rate is exceeded within a 10-second sampling period. When a port is shut down, you receive a log message. From global configuration mode, shutdown is not supported.