7-28 Cisco BPX 8600 Series Reference
Traffic Policing Examples
Leaky Bucket 1
Leaky bucket 1 polices for the PCR compliance of all cells seeking admission to the network, both
those with CLP = 0 and those with CLP =1. For example, cells seeking admission to the network
with CLP set equal to 1 may have either encountered congestion along the user’s network or may
have lower importance to the user and have been designated as eligible for discard in the case
congestion is encountered. If the bucket depth in the first bucket exceeds CDVT (0+1), it discards
all cells seeking admission. It does not tag cells.
With policing set to 1 (VBR.1), all cells (CLP=0 and CLP=1) that are compliant with leaky bucket
1, are sent to leaky bucket 2. With policing set to 2 (VBR.2) or to 3 (VBR.3), all CLP=1 cells
compliant with leaky bucket 1 are admitted directly to the network, and all CLP=0 cells compliant
with leaky bucket 1 are sent to leaky bucket 2.
Leaky Bucket 2
For VBR connections, the purpose of leaky bucket 2 is to police the cells passed from leaky bucket
1 for conformance with maximum burst size MBS as specified by BT and for compliance with the
SCR sustained cell rate. The types of cells passed to leaky bucket 2 depend on how policing is set:
• For policing set to 5, cells bypass both buckets.
• For policing set to 4, leaky bucket 2 sees no traffic.
• For policing set to 2 or 3, the CLP(0) cells are admitted to the network if compliant with BT +
CDVT of leaky bucket 2. If not compliant, cells may either be tagged (policing set to 3) or
discarded (policing set to 2).
• For policing set to 1, the CLP(0) and CLP(1) cells are admitted to the network if compliant with
BT + CDVT of leaky bucket 2. If not compliant, the cells are discarded. There is no tagging
option.
