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 1 The BPX Switch: Functional Overview
BPX Switch Operation
Figure 1-4 Frame Relay to ATM Network Interworking
Service Interworking
Figure 1-5 shows a typical example of Service Interworking. Service Interworking is supported by the
FRSM on the MGX 8220 and the UFM-C and UFM-U on the IGX switch. Translation between the Frame
Relay and ATM protocols is performed in accordance with RFC 1490 and RFC 1483.
Unlike Network Interworking, in a Service Interworking connection between an ATM port and a Frame
Relay port, the ATM device does not need to be aware that it is connected to an interworking function.
The Frame Relay service user does not implement any ATM specific procedures. Also, the ATM service
user does not need to provide any Frame Relay specific functions. All translational (mapping functions)
are performed by the intermediate interworking function.
This is a typical configuration for service interworking:
•
MGX 8220 Frame Relay (FRSM card) to BPX switch or MGX 8220 ATM port.
•
IGX switch Frame Relay (FRM-U or FRM-C) to BPX switch or MGX 8220 ATM port.
H8225
CPE
Part A
Network interworking connection from CPE Frame Relay port
to CPE Frame Relay port across an ATM Network with the
interworking function performed by both ends of the network.
Part B
Network interworking connection from CPE Frame Relay port
to CPE ATM port across an ATM network, where the network
performs an interworking function only at the Frame Relay end
of the network. The CPE receiving and transmitting ATM cells at
its ATM port is responsible for exercising the applicable service
specific convergence sublayer, in this case, (FR-SSCS).
Frame
Relay
Frame
Relay
Frame
Relay Frame
Relay
ATM
ATM network
FR-SSCS
Inter-
working
function
B-ISDN
FR-SSCS
Inter-
working
function
B-ISDN
CPE
CPE
Frame
Relay
Frame
Relay
Frame
Relay
ATM network
FR-SSCS
Inter-
working
function
B-ISDN
CPE
exercises
appropriate
SSCS
B-ISDN
FR-SSCS