Communication Interfaces
The HSS interfaces external high-speed data links to either the 3745 or the 3725:
Remotely via DCE attachment
Locally via direct attachment to another HSS or LIC type 3/4 on the 3725.
The physical and logical interfaces are either:
CCITT V.35 or,
CCITT X.21 leased (including French Transfix).
The high-speed data links access the HSS directly through the FESH via the tail gate without a LIC card.
FESH-DCE Interface
The FESH is physically able to support two interfaces. However, only one interface can be active and
communicating, while the other interface is disabled.
The NCP controls the enabling and disabling of each interface.
On reception of the line address activation from the NCP, the microcode sets the corresponding bit in the
FESH to select the proper port.
To determine which interface was selected by the hardware (V.35 or X.21) on the selected port, the micro-
code reads the cable ID in the FESH.
The FESH is also capable of supporting different electrical interfaces.
Each of the two physical interfaces can independently support the following interfaces to the network com-
munication terminal equipment (NCTE):
V.35
X.21
Any combination of physical interfaces are supported. The physical interface is identified by cable ID
signals in the cable. The following combinations are possible:
Two V.35 interfaces
Two X.21 interfaces
One V.35 and one X.21 interface
NOTE: Before unplugging the cable from the tail gate or DCE, ensure that the line is not active by
disabling the interface, using VTAM commands.
Failure to perform this step can cause an FESH adapter check.
5-40
IBM 3745 Models 130, 150, 160, 170, and 17A: Hardware Maintenance Reference
Summary of Contents for 3745 Series
Page 2: ......
Page 12: ...x IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 14: ...xii IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 18: ...xvi IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 21: ...3745 Models 130 150 160 and 170 Data Flow Chapter 1 General Information 1 3 ...
Page 149: ...For RACs 241 to 244 ERR bits Data received from the adapter Chapter 3 Buses 3 57 ...
Page 166: ...4 14 IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 169: ...Chapter 4 Transmission Subsystem TSS 4 17 ...
Page 322: ...6 28 IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 348: ...7 26 IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 625: ...The ESS in 3745 Models 130 150 160 and 170 Data Flow Chapter 12 Ethernet Subsystem ESS 12 3 ...
Page 674: ...X 6 IBM 3745 Models 130 150 160 170 and 17A Hardware Maintenance Reference ...
Page 708: ......
Page 711: ......
Page 712: ...IBM Part Number 03F5010 Printed in Denmark by IBM Danmark A S ð3F5ð1ð SY33 2ð66 4 ...