System information

Troubleshooting IBM
Book Title
10-236
Figure 10-5 Strapping DTR to RT
SDLC: Intermittent Connectivity
Symptom: User connections to hosts time out over a router configured to perform SDLC transport.
Table 10-10 outlines the problem that might cause this symptom and describes solutions to that
problem.
Table 10-10 SDLC: Intermittent Connectivity
Link-layer problem (router is
secondary)
Example:
In the following example, serial interface 1 is configured for NRZI
encoding:
interface serial 1
nrzi-encoding
Step 7
Try reducing the line speed to 9600 bps using the clock rate interface
configuration command. Use the clock rate interface configuration
command to configure the clock rate for the hardware connections on
serial interfaces such as NIMs and interface processors to an acceptable
bit rate.
Syntax:
The following is the syntax of the clock rate command:
clock rate bps
Syntax Description:
• bps—Desired clock rate in bits per second: 1200, 2400, 4800, 9600,
19200, 38400, 56000, 64000, 72000, 125000, 148000, 250000,
500000, 800000, 1000000, 1300000, 2000000, 4000000, or
8000000.
Example:
The following example sets the clock rate on the first serial interface to
64000 bits per second:
interface serial 0
clock rate 64000
Step 8
Make sure that cabling is correct, securely attached, and undamaged.
1 DCE = full-duplex data communications
2 DTR = data terminal ready
3 RTS = request to send
4 To reduce the amount of screen output produced by the debug sdlc command, configure the sdlc poll-pause-timer 1000 command
to reduce the frequency at which the router sends poll frames. Remember to return this command to its original value (the default is
10 milliseconds).
5 SNRM = send normal response mode
6 UA = unnumbered acknowledgment
7 SCT/SCTE = serial clock transmit/serial clock transmit external
8 NRZ = nonreturn to zero
9 NRZI = nonreturn to zero inverted
10 NIM = network interface module
Possible Problem Solution
Router
SDLC device
RTSRTS
DTR