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About CP-Limit and SMLT IST

Control packet rate limit (CP-Limit) controls the amount of multicast and/or broadcast traffic that can be sent to the CPU from a physical port. It protects the CPU from being flooded by traffic from a single, unstable port. The CP-Limit default settings are:

If the actual rate of packets-per-second sent from a port exceeds the defined rate, then the port is administratively shut down to protect the CPU from continued bombardment.

Disabling IST ports in this way could impair network traffic flow, as this is a critical port for SMLT configurations.

Nortel Networks recommends that an IST MLT contain at least 2 physical ports, although this is not a requirement. Nortel Networks also recommends that CP-Limit be disabled on all physical ports that are members of an IST MLT.

Disabling CP-Limit on IST MLT ports forces another, less-critical port to be disabled if the defined CP-Limits are exceeded. In doing so, you preserve network stability should a protection condition (CP-Limit) arise. Please note that, although it is likely that one of the SMLT MLT ports (risers) would be disabled in such a condition, traffic would continue to flow uninterrupted through the remaining SMLT ports.


Note Note: CP-Limit can only be configured from the CLI.

The command syntax to disable CP-limit is:

config ethernet <slot/port> cp-limit <enable|disable>

See also:


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