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 22 Configuring Frame Relay to ATM Network and Service Interworking
Connection Management
Bandwidth Management
Bandwidth calculations for interworking connections assume a large frame size, which minimizes the
loading inefficiency of packets vs. cells. In other words, the translation between packets and cells
assumes 100 percent efficiency, so the conversion is simply based on 20 payload bytes per fastpacket
versus 48 payload bytes per ATM cell.
This mechanism keeps the fastpacket/cell conversion consistent with the bits per second/cells per
second conversion. Thus, conversion of endpoint rates to trunk loading is straightforward.
User Interface
ATM connection classes are added for convenience. Classes can be configured as interworking or
regular ATM. The cnfcls command is used to configure a class. The class is specified as part of the
addcon command. ATM connection classes are maintained on all BPX switch.
A special ATM class is defined as the default interworking class. When an interworking connection is
added from the Frame Relay end, the ATM-only parameters for this connection are taken from this
default class.
Network-wide ForeSight parameters are supported for the Frame Relay end of interworking
connections. The cnffstparm command is used to configure these parameters. Since the ATM end of
interworking connections has per-virtual circuit ForeSight parameter configurability, the network-wide
ForeSight parameters do not apply.
Note that the default ATM ForeSight parameters will match the default Frame Relay ForeSight
parameters, with appropriate units conversion.
Port Management
The cnfport command supports these features:
•
A UNI or NNI port can be configured to transmit Backwards Congestion Messages (BCM) to
indicate congestion to the foreign ATM network.
• AUNI or NNI port can be configured for LMI, ILMI or no local management.
The cnfportq command supports configuration of queue depth, EFCN threshold, and CLP thresholds
for all port egress queues (CBR, VBR, VBR w/ForeSight).
Signaling
System software supports these LMI/ILMI signaling actions:
•
Internal network failure: software informs LMI/ILMI to set Abit = 0 for failed connections.
• Port failure/LMI Comm Failure: software informs remote nodes terminating all affected
connections. Remote node BCC informs LMI/ILMI to set Abit = 0.
• LMI A = 0: software polls ILMI agent periodically for Abit status. Status changes are reflected in
the ‘dspcon’ screen.