System information

Troubleshooting Dialin Connections
Book Title
16-350
Dialin: Modem Does Not Dial
Symptom: Dialin sessions cannot be established because the modem does not dial properly.
Table 16-3 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 16-3 Dialin: Modem Does Not Dial
Hardware problem
Step 1 Verify that you are using the correct cabling and that all connections
are good.
Step 2 Check all hardware for damage, including cabling (broken wires),
adapters (loose pins), access server ports, and modem.
Step 3 See Chapter 3, “Troubleshooting Hardware and Booting Problems,”
for more information on hardware troubleshooting.
Possible Causes Suggested Actions
Incorrect cabling
Step 1 Check the cabling between the modem and the access server or router.
Confirm that the modem is connected to the auxiliary port on the access server
or router with a rolled RJ-45 cable and an MMOD DB-25 adapter. This
cabling configuration is recommended and supported by Cisco for RJ-45
ports. (These connectors are typically labelled “Modem.”)
Types of RJ-45 Cabling:
There are two types of RJ-45 cabling: straight and rolled. If you hold the two
ends of an RJ-45 cable side-by-side, you’ll see eight colored strips, or pins, at
each end. If the order of the colored pins is the same at each end, then the
cable is straight. If the order of the colors is reversed at each end, then the
cable is rolled.
The rolled cable (CAB-500RJ) is standard with Cisco’s 2500/CS500.
Note: CAB-OCTAL-ASYNC, the eight-port RJ-45 adapter that is used with
the Cisco 2509, 2510, 2511, and 2512, is the same as a rolled cable.
RJ-45 Port Pinouts:
This chart shows the pinouts for RJ-45 console and AUX ports. The console
port does not use RTS/CTS:
Console/Auxiliary Port (DTE
1
)
Pin Signal Input/Output
1 RTS Output
2 DTR Output
3 TXD Output
4 GND —
5 GND —
6 RXD Input
7 DSR Input
8 CTS Input
Step 2 Use the show line exec command to verify that the cabling is correct. See the
explanation of the show line command output in the section “Using debug
Commands” earlier in this chapter.
Possible Causes Suggested Actions