Cisco BPX 8650, Installation And Configuration Manual

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21-51
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.30, Part Number 78-12907-01 Rev. E0, May 2005
Chapter 21 Configuring ATM Connections
Traffic Policing Examples
Figure 21-27 VBR.3 Connection, Policing = 3, with Bucket 2 non-Compliant
ABR Connection Policing
Available Bit Rate (ABR) connections are policed the same as the VBR connections, but in addition use
either the ABR Standard with VS/VD congestion flow control method or the ForeSight option to take
advantage of unused bandwidth when it is available.
UBR Connection Policing
The contract for a unspecified bit rate connection is similar to the ABR connection service for bursty
data. However, UBR traffic is delivered only when there is spare bandwidth in the network.
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 21-28.
Leaky Bucket 1
Leaky bucket 1 polices the UBR connection for PCR compliance. When CLP=No (UBR.1), all cells that
are compliant with leaky bucket 1 are applied to the network. However, these cells are treated with low
priority in the network with a percentage utilization default of 1 percent.
CLP=1
5
CLP=0
4
CLP=1
3
CLP=0
2
CLP=0
1
+
PCR(0+1)
CDVT(0+1)
Time
interval
variations
Leaky Bkt 1
Connection setup
and compliance status:
VBR.3
Policing = 3
Bkt 1 depth < CDVT(0+1)
Bkt 2 depth > BT + CDVT
S6350
Leaky Bkt 1
discards
if depth >
CDVT(0+1)
+
SCR
BT + CDVT
Leaky Bkt 2
CLP=1
5
CLP=1
3
CLP=0
4
CLP=0
2
CLP=0
1
CLP=0
4
CLP=1
2
CLP=1
1
CLP(1) cells compliant with Leaky Bkt 1, admit to network
CLP(0) cells
compliant with
Leaky Bkt 1
are applied to
Leaky Bkt 2 Two CLP(0) cells, 1 and 2,
are shown as non-compliant
with the BT + CDVT limit of
Leaky Bkt 2. With policing = 3,
the cells are tagged as CLP=1
and admitted to the network.