User Manual
UMN:CLI
V8102
343
PIR and CIR are the regenerating rate of tokens for PBS and CBS respectively, which is
measured in bytes of IP packets per second. PIR must be equal to or greater than CIR.
PBS and CBS are the maximum size for each token bucket, P and C, measured in bytes.
Both of them must be configured with the values equal to or greater than the size of the
largest possible IP packet in the stream.
The token buckets P and C are initially full. When a packet arrives, if the tokens in the
bucket P are smaller than the size of that packet, the packet is marked red. Else, if the to-
kens in the bucket C are smaller than the size of that packet, those are decremented by
the size of that packet with the yellow color-marking. Else, if the tokens in the bucket C
are larger than the size of that packet, those of both bucket P and C are decremented by
the size of that packet with the green color-marking.
Note that in the trTCM algorithm, when a packet arrives, the availability of tokens in the
token bucket P is checked first contrary to the srTCM; the order of color-marking is red-
yellow-green.
The following figures show the behavior of the trTCM.
Token
Packet
Token
PBS
CBS
Bucket P
Bucket C
Green Color-Marking
Tokens are regenerated
based on CIR
Tokens in both buckets are
decremented by the size of
the packet
Token
Tokens are regenerated
based on PIR faster than CIR
Fig. 9.11
Behavior of trTCM (1)
