Configuration Considerations for Bridge Domain-based Rate Limiting

• Bridge domain-based rate limiting coexists and works in parallel with all other ACL and rate-limiting features.
• Bridge domain-based rate limiting applies only to ingress traffic only. Egress traffic is blocked by the SLX-OS device.
• There is one policer per ACL, which applies to all the rules for that ACL.
• One thousand and twenty four (1,024) TCAM entries are shared between BD rate limiting and DAI features on a first-come first serve basis.
• Packets drops caused by any action other than ACL rate limiting are included in policing counters.
• Only a permit clause in an ACL rule is subject to rate limit traffic calculations. A deny clause does not result in a policing action.
• Metering is performed at Layer 1 on the packet size as received on the wire (including IPG, Preamble and SOF, ignoring FCS/CRC).
• A policy map can be applied to a physical port, a LAG interface, and a system.
• Multiple class maps with user ACLs can be added in a policy map. However, when a matching ACL clause is found, the device does not evaluate subsequent ACL clauses and rate limits those ACLs.
• A configured rate in bps is rounded up to the next achievable rate.
• The device does not support the specifying of actions to perform on traffic with a color-class priority, such as having packet DSCP priority, traffic class (internal queue assignment), or traffic class (internal queue assignment) set to specific values.
• Statistics display only two colors. Conform includes Green and Yellow packets. Violated includes dropped or a RED packet.
• You cannot delete a policy map that is active on the interface.
• You cannot delete a class map from a policy map when the policy map is active on the interface.
• Configure the Committed Information Rate (CIR) and Excess Information Rate (EIR) in multiples of 22 kbps. If the value is below 22 kbps, then 22 kbps is programmed in the device.
• If a police map is applied to an interface and no policer attributes are present in that policy map, then ingress and egress packets on that interface are marked as green (conforming).
• If the Committed Burst Size (CBS) and Excess Burst Size (EBS) values are not configured, then these values are derived from CIR and EIR values, respectively. The burst size calculation is as follows:
  

  Burst size (CBS or EBS) =1.2*information rate (CIR/EIR)/8

• If the configured CBS value is less than 2*MTU value, then 2*MTU is programmed as the CBS in the hardware.
• If you do not configure EIR, then the Single-rate Three Color scheme (SrTCM) is applied.
• You must configure rate limit threshold values on an interface based on interface speed.
• No validation is performed for user-configured values against interface speed.
• A policy map cannot be bound to interface if a class map is not associated with that policy map.