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Cisco MGX 8220 Installation and Configuration
Release 5.0, Part Number 78-6430-03 Rev. D0, November 2003
Chapter Frame Relay Service Modules (FRSMs)
An application of a BSTUN connection is sho wn in F igure4-6. A Bisync device, such as an IBM 3270,
is connected to a FRASM port using Bisync protoc ol. The traffic is first converted to Frame Relay and
then to ATM cells for transmission over the network. At the other end , the traffic is first converted back
to Frame Relay and the Bisync tr affic is th en ex tr act ed f or t ra nsmi ssion to a front end communica tio n
processor and then to the IBM m ai nfr am e .
Figure4-6 Using FRASM for a BSTUN Connection
Using BSTUN, FRASM supports
•Point-to-point Bisync lines.
•Multidropped Bisync devices over a sin g le lo gical port. These can be assigned to differ en t
connections.
•Multiple logical connections over a single logical port.
•Virtual multidrop in which Bisync devices attached to a FRAM on a different MGX 8220 shelf can
be configured to appear on multidropped devices on a single multidrop line.
FRAS Connections
FRAS BNN, short for Frame Relay Boundary Network Node, is a technique for encapsulating
SDLC/SNA traffic into Frame Relay fr ame s (to RFC 1490) at one end of the co nn ec ti on o nl y. At the
other end of the connectio n, the data is presented as Frame Relay. This is used for conn ecting an SDLC
device at one end to a Frame Relay device at the other.
SNA traffic received by the FRASM is converted first to a Frame Relay format and is then further
converted into cells for transmissio n over an ATM network, t he ATM traffic is then converted back to
Frame Relay at the other end.
Using FRASM configured for FRAS BNN con nect ions , m any l ow s p eed SNA lines can be consolidated
into a smaller number of high-speed lines for fast transport through the network. In addition, FRAS
BNN can be used for high-speed links between IBM front end processors (FEPs). FEPs running under
Network Control Program (NCP) 7.1 support BNN.
An application of a FRAS BNN connection is shown in Figure 4-7. An SDLC device is connected to an
FRASM port using SDLC protocol. T he traffic is first c onverted to Frame Relay and then to ATM cells
for transmission over the network. At the other end, the traffic is first converted back to Frame Relay
for transmission to a front- en d c om m u ni cat io n pr o cess o r an d th en t o t h e I BM m ainframe.
Remote Bisynch
End User Device Bisynch FRASM
ATM network
Frame Relay
over ATM
MGX
8220 MGX
8220 FRASM Bisynch Front-end
Processor
NCP1
Mainframe
VTAM1
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