Cisco BPX 8650, Installation And Configuration Manual

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Cisco BPX 8600 Series Installation and Configuration
Release 9.3.30, Part Number 78-12907-01 Rev. E0, May 2005
Chapter 5 BXM Card Sets: T3/E3, 155, and 622
BXM Functional Description
For ingress traffic, the BXM physical interface:
1. Receives incoming SONET/SDH frames.
2.
Extracts ATM cell payloads.
3.
Processes section, line, and path overhead.
For egress traffic ATM cells are processed into SONET/SDH frames.
Alarms and statistics are collected at each level: section, line, and path.
Demultiplexing and Multiplexing
Demultiplexing, multiplexing, and associated circuits implement the BXM physical layer processing for
T3/E3 interfaces, processing functions for T3 at a 44.736 Mbps rate, or E3 at a 34.368 rate.
The following are the functions for demultiplexing and multiplexing:
•
Header processing
•
Framing
• ATM layer mapping
RCMP
Usage Parameter Control (UPC) is provided by the Routing Control, Monitoring, and Policing (RCMP)
ASIC. Each arriving ATM cell header is processed and identified on a per VC basis. The policing
function utilizes a leaky bucket algorithm.
In addition to UPC and traffic policing, the RCMP provides route monitoring and also terminates OAM
flows to provide performance monitoring on an end-to-end per VC/VP basis.
Traffic policing and UPC functionality is in accordance with the Generic Cell Rate Algorithm (GCRA)
as specified by ATM Forum’s UNI 3.1 using dual leaky buckets.
• Leaky Bucket 1 utilizes:
–
Peak Cell Rate (PCR)
– Cell Delay Variation Tolerance: CDVT
•
Leaky Bucket 2 utilizes:
–
Sustainable Cell Rate (SCR)
–
Maximum Burst Size (MBS)
In addition, two selective cell discard thresholds are supported for all queues for discard of CLP=1 cells
should congestion occur.
SABRE
The Scheduling and ABR Engine (SABRE) includes both VS/VD and ForeSight dynamic traffic transfer
rate control and other functions:
•
ATM Forum Traffic Management 4.0 compliant ABR Virtual Source/Virtual Destination (VS/VD).
•
Terminates ABR flows for VS/VD and ForeSight control loops.
•
Performs explicit rate (ER) and EFCI tagging if enabled.