JUNOSe 7.2.x Policy Management Configuration Guide
88 ! One-Rate Rate-Limit Profiles
Transmit-unconditional packets entering a color-aware rate limit uses the color on
the packet for the rate-limit algorithm. Doing this ensures that the color-aware rate
limit depletes tokens from the token buckets to account for these packets.
Every packet sent through a rate-limit hierarchy is either dropped inside the
hierarchy or emerges with a green, yellow, or red color assigned to it by the
rate-limit hierarchy. The color depends on the last rate limit in the hierarchy that
owned the packet and all prior rate limits. The green, yellow, or red classification
applies to packets of any type and is not interface-type dependent.
A packet that has traversed the hierarchy either has been dropped or emerges with
a color (green, yellow or red). This final color can be used by a mark rule with a
color-mark profile to select the ToS marking for the packet. Because this operation
is interface-type dependent, the actual value is configured where the packet entered
the hierarchy; however, the color is set by the entire rate-limit hierarchy.
One-Rate Rate-Limit Profiles
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.
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
NOTE: Commands that you issue in Rate Limit Profile Configuration mode do not
take effect until you exit from that mode.
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