Two-Rate Three-Color Policer Overview
A two-rate three-color policer defines two bandwidth limits (one for guaranteed traffic and one for peak traffic) and two burst sizes (one for each of the bandwidth limits). A two-rate three-color policer is most useful when a service is structured according to arrival rates and not necessarily packet length.
Two-rate three-color policing meters a traffic stream based on the following configured traffic criteria:
Committed information rate (CIR)—Bandwidth limit for guaranteed traffic.
Committed burst size (CBS)—Maximum packet size permitted for bursts of data that exceed the CIR.
Peak information rate (PIR)—Bandwidth limit for peak traffic.
Peak burst size (PBS)—Maximum packet size permitted for bursts of data that exceed the PIR.
Two-rate tricolor marking (two-rate TCM) classifies traffic as belonging to one of three color categories and performs congestion-control actions on the packets based on the color marking:
Green—Traffic that conforms to the bandwidth limit and burst size for guaranteed traffic (CIR and CBS). For a green traffic flow, two-rate TCM marks the packets with an implicit loss priority of low and transmits the packets.
Yellow—Traffic that exceeds the bandwidth limit or burst size for guaranteed traffic (CIR or CBS) but not the bandwidth limit and burst size for peak traffic (PIR and PBS). For a yellow traffic flow, two-rate TCM marks packets with an implicit loss priority of medium-high and transmits the packets.
Red—Traffic that exceeds the bandwidth limit and burst size for peak traffic (PIR and PBS). For a red traffic flow, two-rate TCM marks packets with an implicit loss priority of high and, optionally, discards the packets.
If congestion occurs downstream, the packets with higher loss priority are more likely to be discarded.
For both single-rate and two-rate three-color policers, the only configurable action is to discard packets in a red traffic flow.
For a tricolor marking policer referenced by a firewall filter term, the discard policing action is supported on the following routing platforms:
EX Series switches
M7i and M10i routers with the Enhanced CFEB (CFEB-E)
M120 and M320 routers with Enhanced-III FPCs
MX Series routers with Trio MPCs
To apply a tricolor marking policer on these routing platforms, it is not necessary to include the logical-interface-policer statement.