Expand Configuration and Management Manual (H06.21+, J06.10+)

Glossary
Expand Configuration and Management Manual — 529522-013
Glossary - 4
Expand packet
Expand packet. See Expand frame.
Expand priority. The priority of an Expand message. The Expand priority is based on the
priority level of the application process that created the message, unless the
SETMODE 71 procedure is used.
frame. See Expand frame.
global variables space. A portion of the Expand line-handler process data space that
contains Expand software global variables. The Expand subsystem determines how
much global variables space to allocate according to the number of lines in a path
controlled by the Expand line-handler process.
HC. See hop count (HC).
HDLC Extended Mode protocol. See High-Level Data Link Control (HDLC) Extended
Mode protocol.
HDLC Normal protocol. See High-Level Data Link Control (HDLC) Normal protocol.
High-Level Data Link Control (HDLC) Extended Mode protocol. The protocol used by
the satellite-connect line-handler process. Unlike the HDLC Normal protocol
implemented by direct-connect Expand line-handler processes, the HDLC Extended
Mode protocol uses the maximum window size of 61 frames (the maximum number of
outstanding frames before an acknowledgment is required) and implements the
selective reject feature. Selective reject causes only frames that arrive in error to be
retransmitted. See also High-Level Data Link Control (HDLC) Normal protocol.
High-Level Data Link Control (HDLC) Normal protocol. The protocol used by the direct-
connect line-handler process. The direct-connect line-handler process is provided for
use with conventional voice-grade leased-line and switched-line facilities, private
facilities, and fractional Transmission Group 1 (T1) facilities. See also
High-Level Data
Link Control (HDLC) Extended Mode protocol.
hop count (HC). The number of intervening nodes on a route. HC is used to determine the
best path route: if two alternative routes have the same time factor (TF), the route with
the lowest HC is the best route. See also
best-path route and time factor (TF).
Layer 2. A term that is used to refer to the Data Link Layer of the Open Systems
Interconnection (OSI) Reference Model. Layer 2 defines rules for transmission on the
physical medium. Direct-connect and satellite-connect Expand line-handler processes
provide the High-level Data Link (HDLC) protocol at Layer 2. Expand-over-NAM line-
handler processes use the Layer 2 services provided by either the SNAX/APN or
X25AM subsystems. Expand-over-ServerNet line-handler processes use the Layer 2
services provided by the ServerNet monitor process, $ZZSCL. Expand-over-IP line-
handler processes use the Layer 2 services provided by NETIP protocol. Expand-over-
ATM line-handler processes use the Layer 2 services provided by the NETATM
protocol. The Expand line-handler process’s Data Link Layer, or line functions,