Variable Bit Rate Connections; Table 21-9 Cbr Policing Definitions - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

Chapter 21 Configuring ATM Connections
The parameters for a CBR connection are shown in Figure 21-6 in the sequence in which they occur
during the execution of the addcon command. The CBR policing definitions are summarized in
Table 21-8.
Figure 21-6 CBR Connection Prompt Sequence
CBR
PCR(0+1)
%Util
CDVT(0+1)
Policing (4 or 5)
Trunk cell routing
restrict (Y/N) [Y]
For policing prompt:
1
4 = PCR policing only
5 = policing off
Note: BW allocation = (PCR)x(%Util)

Table 21-9 CBR Policing Definitions

Connection
Type
CBR
CBR

Variable Bit Rate Connections

VBR (variable bit rate) connections may be classified as either:
•
•
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
1
ATM Forum TM spec. 4.0
conformance definition
CBR.1
when policing set to 4
(PCR Policing only)
When policing set to 5
(off)
Real-Time Variable Bit Rate (rt-VBR)
This category is used for connections that transmit at a rate varying with time and can be described
as bursty, often requiring large amounts of bandwidth when active. It is intended for applications
that require tightly constrained delay and delay variation such as compressed voice video
conferencing.
For example, video conferencing requires real-time data transfer with bandwidth requirements that
can vary in proportion to the dynamics of the video image at any given time. The rt-VBR category
is characterized in terms of PCR, SCR (sustained cell rate), and MBS (maximum burst size).
Non-Real Time Variable Bit Rate (nrt-VBR)
This category is used for connections that are bursty but not constrained by delay and delay
variation boundaries. For those cells in compliance with the traffic contract, a low cell loss is
expected. Non-time critical data file transfers are an example of an nrt-VBR connection. A nrt-VBR
connection is characterized by PCR, SCR, and MBS.
PCR Flow CLP tagging
(1st leaky (for PCR
bucket) flow)
CLP(0+1) no
off n/a
Cisco BPX 8600 Series Installation and Configuration
ATM Connection Configuration
SCR Flow CLP tagging
(2nd leaky (for SCR
bucket) flow)
off n/a
off n/a
21-29