Adjust Minimum Scr And Pcr; Constant Bit Rate Connections; Table 21-8 Supported Cards And Performance Specifications - Cisco BPX-BXM-155-8DX Installation And Configuration Manual

ATM Connection Configuration
Table 21-7 Connection Parameter Descriptions (continued)
Parameter
IBS
Trunk cell routing restriction
(Y/N) [Y]

Adjust Minimum SCR and PCR

Prior to Release 9.3.0, the minimum Sustainable Cell Rate (SCR) and Peak Cell Rate (PCR) of a
connection supported by the BXM and UXM cards, including enhanced modes, was 50 cells per second
(cps). These values were set to maintain a policing accuracy with 1% when policing is performed on a
BXM or UXM card. Because of this limitation, it was impossible to offer and differentiate connection
services on a UXM or BXM at speeds less than 19.2 Kbps.
In Release 9.3.0, the switch software supports connections with policing enabled and with SCR and
PCR values as low as 12 cps on the BPX with certain card limitations.
Use the dspcd command to determine if this feature is supported on a given slot.
Use the addcon command to set the minimum SCR and PCR values. If these values are less than the
minimum values supported on a given card, the command line interface will not allow you to set them
until you have disabled policing. (A prompt will let you know about this limitation.)
Please refer to Table 21-1 for a list of cards that are supported by this feature and their performance
specifications.

Table 21-8 Supported Cards and Performance Specifications

Card Name
IGX-UXM
IGX-UXM
IGX-IUX
IGX-UXM
BPX-BXM
BPX-BXM
BPX-BXM
Note: The policing accuracy is always within 1%. The maximum SCR and PCR policing values are the same as the line rate.

Constant Bit Rate Connections

The CBR (constant bit rate) category is a fixed bandwidth class. CBR traffic is more time dependent,
less tolerant of delay, and generally more deterministic in bandwidth requirements.
CBR is used by connections that require a specific amount of bandwidth to be available continuously
throughout the duration of a connection. Voice, circuit emulation, and high-resolution video are typical
examples of traffic utilizing this type of connection.
A CBR connection is allowed to transmit cells at the peak rate, below the peak rate, or not at all. CBR
is characterized by peak cell rate (PCR).
Cisco BPX 8600 Series Installation and Configuration
21-28
Description
Initial Burst Size
The default (Y) restricts ATM connection routes to include only ATM trunks.
Selecting (N) allows the network to route these connections over non-ATM trunks
(such as., Fastpacket trunks).
Card Types
T1/E1
IMA
T3/E3
OC3/STM-1
T3/E3
OC3/STM-1
OC12/STM-4
Chapter 21 Configuring ATM Connections
Minimum SCR and PCR, UPC/NPC Values
6 cps
6 cps
12 cps
50 cps
12 cps
50 cps
50 cps
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001