7-26 Cisco BPX 8600 Series Reference
Traffic Policing Examples
VBR Dual-Leaky Bucket Policing Examples
The contract for a variable bit rate connection is set up based on an agreed upon sustained cell rate
(SCR) with allowance for occasional data bursts at a Peak Cell Rate (PCR) as specified by maximum
burst size MBS.
When a connection is added, a VPI.VCI address is assigned, and UPC parameters are configured for
the connection. For each cell in an ATM stream, the VPI.VCI addresses are verified and each cell is
checked for compliance with the UPC parameters as shown in Figure 7-14.
The VBR cells are not enqueued, but are processed by the policing function and then sent to the
network unless discarded.
For VBR, traffic policing, depending on selected policing option, is based on:
• Leaky bucket 1, PCR and CDVT
• Leaky bucket 2, SCR, CDVT, and MBS
The policing options, selected by entering 1-5 in response to the policing choice prompt, are as
follows for VBR connections:
VBR.1
VBR with policing
set to 1.
CLP(0+1) cells compliant with leaky bucket 1 are passed to leaky bucket 2;
non-compliant cells are discarded. CLP(0+1) cells compliant with leaky bucket 2 are
admitted to the network; non-compliant cells are discarded.
VBR.2
VBR with policing
set to 2.
CLP(1) cells compliant with leaky bucket 1 are admitted to the network; non-compliant
CLP(0+1) cells are dropped. CLP(0) cells compliant with leaky bucket 1 are applied to
leaky bucket 2; non-compliant cells are dropped. CLP(0) cells compliant with leaky
bucket 2 are admitted to the network; non-compliant cells are dropped.
VBR.3
VBR with policing
set to 3.
CLP(1) cells compliant with leaky bucket 1 are admitted to the network; non-compliant
CLP(0+1) cells are dropped. CLP(0) cells compliant with leaky bucket 1 are applied to
leaky bucket 2; non-compliant cells are dropped. CLP(0) cells compliant with leaky
bucket 2 are admitted to the network; non-compliant cells are tagged and admitted to the
network.
VBR with policing
set to 4.
CLP(0+1) cells compliant with leaky bucket 1 are admitted to the network;
non-compliant cells are dropped. Leaky bucket 2 is not active.
VBR with policing
set to 5.
Policing is off, so there is no policing of cells on ingress.
