X25AM Configuration and Management Manual

PTrace for the X25AM Subsystem
X25AM Configuration and Management Manual—523424-004
6-26
Terminals and PAD Parameters
If calls are being accepted but the terminals do not work quite right, a PAD parameter
problem may exist.
Once the Q packets have been sent and the PAD has configured itself to those
parameters, the terminal can communicate with the X25AM-ITI subdevice as if the
subdevice were an actual terminal process.
To analyze the Q packet, look at the following display, which is record 40 from the
previous trace.
The Q bit is set in bit <3> of the first byte of a data packet. The fourth byte determines
the type of Q packet being sent.
SET means that the PAD should configure itself to these parameters and not send a
response. The rest of the packet is for the PAD parameters.
PAD parameters are defined in pairs. The first number of the pair specifies the type of
PAD parameter (that is, 1=escape mode, 2=echo mode). The second number contains
a value that modifies the mode (that is, 2,1 means echo turned on). The parameters
are defined in the X.28 ITU-T standard. For more information about PAD parameters,
consult Support Note S87061, “X25AM ITI OPTIONS CPADPARMS AND
BPADPARMS.”
Some PDNs supply their own PADs. These PDNs usually have their own special
network-related PAD parameters. These parameters usually come after the standard
X.28 parameters, following a National Parameter Marker (NPM) of 2 bytes, the first one
being zero. For example, Telenet’s default conversational parameters are:
(1,1) (4,0) (7,21) (8,0) (10,0) (2,1) (3,126) (0,33) (0,0) (1,2)
The National Parameter Marker for Telenet is (0,33). Everything after the (0,33) is a
Telenet-specific parameter, meaning that the descriptions are not in the ITU-T
specification; consult the Public Data Network (PDN) for meanings. For more
information about NETID, REMOTENET, and PAD parameter values, see Appendix D,
Using the NETID Modifier.
L3 Pkt Out Record 40D Seq 40 Type 50 Time 09:25:28.487673
SDN #002/%002 LEN #0020 GFI(1001) Q MOD8 LGN/LCN $002
Data M=0 P(S)=0 P(R)=0
000: 9002 0002 0101 0400 0715 0800 0A00 0201
008: 037E 0D04
0 Q bit set
0 Packet type (Data packet)
2 SET type Q packet (Configures PAD to following parameters for
conversational mode:
(1,1) (4,0) (7,15) (8,0) (10,0) (2,1) (3,126) (13,4)