Cisco BPX 8600 Series, Руководство по установке и настройке

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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
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.
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).
IBS Initial Burst Size
Trunk cell routing restriction
(Y/N) [Y] 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).
Table 21-7 Connection Parameter Descriptions (continued)
Parameter Description
Table 21-8 Supported Cards and Performance Specifications
Card Name Card Types Minimum SCR and PCR, UPC/NPC Values
IGX-UXM T1/E1 6 cps
IGX-UXM IMA 6 cps
IGX-IUX T3/E3 12 cps
IGX-UXM OC3/STM-1 50 cps
BPX-BXM T3/E3 12 cps
BPX-BXM OC3/STM-1 50 cps
BPX-BXM OC12/STM-4 50 cps
Note: The policing accuracy is always within 1%. The maximum SCR and PCR policing values are the same as the line rate.