Hdlc/Sdlc Mode - 3Com SuperStack II PathBuilder S330 Reference Manual

HDLC/SDLC Mode

Transparent HDLC mode is used for point-to-point HDLC connections across the
ATM network. No service-based encapsulation other than AAL5 is needed. All
packets are terminated and SAR'd (processed via segmentation and relay) to a
single VP/VC in the ATM network.
Transparent mode functionality is best implemented with a PRBS type of pattern
included in a sequence of frames. The TTC Firebird V.35 frame relay interface
provides that simple capability.
When using transparent HDLC mode, you set the following parameters:
Minimum number of flags between HDLC frames
CRC type
The PathBuilder S330/S310 switch will SAR AAL5 and map HDLC/SDLC frames
onto an ATM VCC. You could use the HDLC service for router to router and X.25
to X.25 links. You could use the SDLC service for IBM FID2 3270 SNA Peripheral or
IBM FID4 372X SNA Backbone.
Figure 176 shows HDLC/SDLC applications.
You should disable NRZI on the FEP (i.e., IBM 3745). NRZI is commonly used when
the FEP is connected to DSUs over a non-digital line. The PathBuilder S330 switch
does not require NRZI to be enabled.
Figure 176 HDLC/SDLC Applications
PathBuilder
S330/S310
HDLC
X.25
X.25
P AD
3 FID 4
S
7 SDLC
N
2 FID 2
A
5 SDLC
Host
Serial Interface 245
PathBuilder
S330/S310
HDLC
X.25
X.25
3
7
FID 4
2
5
FID 2
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