# One-Rate Rate-Limit Profiles Overview

E Series routers implement a single-rate rate limiter, which you can configure to provide more efficient service to TCP applications. With the single-rate rate limiter, when the committed rate is exceeded, the rate limiter drops a single packet and then resumes transmission up to a configurable burst window. The single, unacknowledged packet causes TCP to cut its transmission rate in half rather than falling back to its initial window size.

| Note: Commands that you issue in Rate Limit Profile Configuration mode do not take effect until you exit from that mode.

The one-rate rate-limit profile attributes are:

- Color aware—Color-aware rate action (only for hierarchical rate limits)
- Committed rate—Target rate for a packet flow
- Committed burst—Amount of bandwidth allocated to accommodate bursty traffic in excess of the rate
- Excess burst—Amount of bandwidth allocated to accommodate a packet in progress when the rate is in excess of the burst
- Committed action—Drop, transmit, mark (IP and IPv6), or mark-exp (MPLS) when traffic flow does not exceed the rate; the mark value is not supported for hierarchical rate limits and the transmit values conditional, unconditional, or final are only supported on hierarchical rate limits
- Conformed action—Drop, transmit, mark (IP and IPv6), or mark-exp (MPLS) when traffic flow exceeds the rate but not the excess burst; the mark value is not supported for hierarchical rate limits and the transmit values conditional, unconditional, or final are only supported on hierarchical rate limits
- Exceeded action—Drop, transmit, mark (IP and IPv6), or mark-exp (MPLS) when traffic flow exceeds the rate; the mark value is not supported for hierarchical rate limits and the transmit values conditional, unconditional, or final are only supported on hierarchical rate limits
- Mask value—Mask to be applied with mark values for the ToS byte; applicable only to IP and IPv6 rate-limit profiles; not supported on hierarchical rate limits
- EXP mask value—Mask to be applied with mark-exp values; applicable only to MPLS rate-limit profiles; not supported on hierarchical rate limits