Specifications

22-6
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
Networking Interworking
These Frame Relay-to-ATM networking interworking functions are available:
• 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)
• IGX switch Frame Relay (either routing node or shelf/feeder) to BPX switch or MGX 8220 ATM
port
• MGX 8220 Frame Relay to BPX switch or MGX 8220 ATM port
On the IGX switch, interworking is performed by the BTM card.
A simplified example of the connection paths is shown in Figure 22-6. In interworking, the BTM card
receives FastPackets from the FRM, rebuilds the frames, and converts between frames and ATM cells.
Data is removed from one package and placed in the other. Congestion information from the header is
mapped to the new package.
This processing by the BTM trunk card is called Complex Gateway. BTM trunk cards are required on
every BPX switch to IGX switch hop in a Frame Relay to ATM connection’spath.
Figure 22-6 ATF Connections, Simplified Example
The cells within the frame are expected to possess the standard ATM Access Interface cell header. The
traffic is assumed to have AAL-5 PDUs, and will not function properly otherwise (framing errors will
result). Within the AAL-5 PDUs, the data must be packaged in standard Frame Relay frames, one frame
per PDU (with respect to the AAL-5 layer).
The UPC and ForeSight algorithms are applied according to their configured values. The cell headers
are converted into the proprietary Cisco WAN switching STI format before entering the network. The
cells are delivered to their destination according to the configured route of the connection. Cells can be
lost due to congestion.
S5241
CISCO WAN MANAGER
ATM
(T3/E3
Feeder
trunk
ATM
(T3/E3
Frame
Relay (T1)
Feeder
trunk
Some typical ATF connection paths shown:
BXM
BPX HubIGXShelf
BXM
FRM
BTM
Crosspt
switch
ATM
(T3/E3
BXM
BPX
BXM
Crosspt
switch
MGX
8220
Frame
Relay
(T1)
Frame
Relay (T1)
Frame
Relay (T1)
(pvc2)
(pvc3)
IGX
BTM
FRM
Router
ATM
(T3/E3/
OC-3
ATM
(T3/E3/
OC-3
(pvc1)
(pvc3)
CPE
Frame
Relay (T1)
(pvc1)
(pvc2)
Router