Specifications

1-11
Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Chapter 1 The BPX Switch: Functional Overview
BPX Switch Operation
Network Interworking
Part A of Figure 1-4 shows typical Frame Relay to network interworking. In this example, a Frame
Relay connection is transported across an ATM network, and the interworking function is performed by
both ends of the ATM network.
These are typical configurations:
• IGX switch Frame Relay (shelf/feeder) to IGX switch Frame Relay (either routing node or
shelf/feeder).
• MGX 8220 Frame Relay to MGX 8220 Frame Relay.
• MGX 8220 Frame Relay to IGX switch Frame Relay (either routing node or shelf/feeder).
Part B of Figure 1-4 shows a form of network interworking where the interworking function is
performed by only one end of the ATM network, and the CPE connected to the other end of the network
must itself perform the appropriate service-specific convergence sublayer function.
These are sample configurations:
• IGX switch Frame Relay (either routing node or shelf/feeder) to BPX switch or
to MGX 8220 ATM port.
• MGX 8220 Frame Relay to BPX switch or MGX 8220 ATM port.
Network Interworking is supported by the FRM, UFM-C, and UFM-U on the IGX switch, and the
FRSM on the MGX 8220. The Frame Relay Service Specific Convergence Sublayer (FR-SSCS) of
AAL5 is used to provide protocol conversion and mapping.