Specifications
5-6
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Chapter 5 BXM Card Sets: T3/E3, 155, and 622
BXM Capabilities
–
Peak Cell Rate (PCR)
–
Cell Transfer Delay Variation (CTDV)
VBR Service:
• Usage Parameter Control (UPC) and Admission Control
• UPC: Ingress rate monitoring and cell tagging per ITU-T I.371 for:
–
Sustained Cell Rate (SCR)
–
Peak Cell Rate (PCR)
–
Burst Tolerance (BT)
• CLP tagging, enabled or disabled on a per VC basis at the Ingress side
ABR Service:
• Based on Virtual Source Virtual Destination (VSVD) per ATM Forum TM4.0
• VSVD
–
VSVDs provide Resource Management (RM) cell generation and termination to support
congestion control loops
–
A virtual connection queue (VCQ) is assigned to a VC in the ingress direction
–
VCQ configurable parameters
–
CLP Hi and Lo thresholds
Maximum queue depth
Reserved queue depth
Congestion threshold
• ABR congestion control
Based on Explicit rate stamping/EFCI cell tagging and ingress rate monitoring per ITU-T I.371
–
ABR with Virtual Source Virtual Destination (VSVD)
–
ABR with Explicit Rate (ER) stamping/EFCI tagging
–
ABR with ForeSight
UBR Service:
• Based on UPC and admission control including EPD
• Based on Explicit Rate Marking/EFCI cell tagging and ingress rate monitoring per ITU-T I.371
Minimum SCR and PCR
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) or 19.2 Kbps. These
valuesweresettomaintainapolicingaccuracywith1%whenpolicingisperformedonaBXMorUXM
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 (50 cps).
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 switch, 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.