Table 11: Policy Action Applied Based On Rate Settings And Traffic Rate; Table 12: Two-Rate Rate-Limit Profile Algorithms - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - POLICY MANAGEMENT CONFIGURATION GUIDE 2010-10-04 Configuration Manual

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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
Table 11 on page 83 indicates the interaction between the rate settings and the actual
traffic rate to determine the action taken by a rate-limit rule in a policy when applied to
a traffic flow. This implementation is known as a two-rate, three-color marking
mechanism.

Table 11: Policy Action Applied Based on Rate Settings and Traffic Rate

Peak Rate Committed Rate = 0
Peak rate = 0 All traffic assigned the exceeded
action
Peak rate not 0 Traffic <= peak rate assigned the
conformed action
Traffic > peak rate assigned the
exceeded action
Table 12 on page 83 presents equations that can represent the algorithm for the two-rate
rate-limit profile, where:
B = size of packet in bytes
Tp = size of peak token bucket in bytes (maximum size of this bucket is the configured
peak burst)
Tc = size of the committed token bucket in bytes (maximum size of this bucket is the
configured committed burst)
t = time

Table 12: Two-Rate Rate-Limit Profile Algorithms

Step
If not color-aware, use green as the
incoming packet color, otherwise use the
actual packet color
If incoming packet color is green:
If Tc(t) >= B
Chapter 5: Creating Rate-Limit Profiles
Committed Rate Not 0
Traffic <= committed rate
assigned the committed action
Traffic > committed rate assigned
the exceeded action
Traffic <= committed rate
assigned the committed action
Committed rate < Traffic < peak
rate assigned the conformed
action
Traffic > peak rate assigned the
exceeded action
Result
–
–
Packet is marked as green
Tc(t) is decremented by B
Tp(t) is decremented by B (allow Tp(t) < 0 if
necessary)
83