Traffic Policing Overview

Rate limiting and shaping

Rate limiting controls the amount of bandwidth that is consumed by an individual flow or an aggregate of flows. For inbound and outbound traffic, rate limiting drops packets that exceed committed rates.

For more information, see the following topics.

• VLAN-based rate limiting
• Bridged-domain based rate limiting
• Receive ACL Rate Limiting
• Egress ACL Rate Limiting
• Rate Limiting Scalability

Rate shaping controls traffic bursts applicable to egress traffic by buffering and queuing excess packets that are above the committed rate.

CIR and EIR

The Committed Information Rate (CIR) is the amount of available bandwidth that is committed to the user. Available bandwidth should not fall below this committed rate.

The Excess Information Rate (EIR) is an accommodation that you configure for traffic that exceeds the CIR.

For more information, see:

• Committed Information Rate and Committed Burst Size
• Excess Information Rate and Excess Burst Size

Color markers

The single-rate, three-color marker (SrTCM) and the two-rate, three-color marker (TrTCM) indicate traffic compliance with bandwidth requirements. SrTCM is based on RFC 2697. TrTCM is based on RFC 4115.

For more information, see:

• Single rate three color marker
• Two-rate, three-color marker

Service policies

A service policy consists of a policy map that specifies traffic policing rules and QoS parameters that match associated class maps. One service policy can be applied per interface, per direction.

For more information, see:

• Service Policy Configuration Rules
• Policy Maps
• Class Maps

Storm control

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

For more information, see Storm Control for Broadcast, Unknown Unicast, and Multicast Traffic.