Specifications

21-29
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Chapter 21 Configuring ATM Connections
ATM Connection Configuration
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
Variable Bit Rate Connections
VBR (variable bit rate) connections may be classified as either:
• 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.
Table 21-9 CBR Policing Definitions
Connection
Type
ATM Forum TM spec. 4.0
conformance definition
PCR Flow
(1st leaky
bucket)
CLP tagging
(for PCR
flow)
SCR Flow
(2nd leaky
bucket)
CLP tagging
(for SCR
flow)
CBR CBR.1
when policing set to 4
(PCR Policing only)
CLP(0+1) no off n/a
CBR Whenpolicingsetto5
(off)
off n/a off n/a
CBR
PCR(0+1)
%Util
CDVT(0+1)
Policing (4 or 5)
For policing prompt:
4 = PCR policing only
5 = policing off
Note: BW allocation = (PCR)x(%Util)
10224
1
1
Trunk cell routing
restrict (Y/N) [Y]