After the serial port mode is configured as Sync, connect the DCE type serial cable to one side and DTE cable on the other side. The serial link will come up. Use the following command to check cable type:

Router1#show controllers Serial 0/3/0

Serial0/3/0 - (IRM-NIM-RS232) is administratively down
 Encapsulation : HDLC
 Cable type: RS-232 DCE
 mtu 1500, max_buffer_size 1524, max_pak_size 1656 enc 132
 loopback: Off,  crc: 16, invert_data: Off
 nrzi: Off, idle char: Flag
 dce_terminal_timing_enable: Off ignore_dtr: Off
 tx_clockrate: 64000bps, rx_clockrate: 64000bps, serial_clock_index: 0
 serial_restartdelay:60000,  serial_restartdelay_def:60000

     RTS up, CTS down, DTR up, DCD down, DSR down

Router1#

Router2#show controllers Serial 0/3/1

Serial0/3/1 - (IRM-NIM-RS232) is administratively down
 Encapsulation : HDLC
 Cable type: RS-232 DTE
 mtu 1500, max_buffer_size 1524, max_pak_size 1656 enc 132
 loopback: Off,  crc: 16, invert_data: Off
 nrzi: Off, idle char: Flag
 tx_invert_clk: Off, ignore_dcd: Off
 tx_clockrate: 31998bps, rx_clockrate: 31998bps, rx_clock_threshold: 0
 serial_restartdelay:60000,  serial_restartdelay_def:60000

     RTS down, CTS down, DTR down, DCD down, DSR down

Router2#

The show interfaces serial0/3/0 controller command can also be used to check the cable type.

The synchronous serial interfaces support the following serial encapsulation methods:

• Frame-Relay

• PPP (chap and pap)

• HDLC (default)

Use the following command to configure synchronous serial encapsulation. To remove the configuration, use the no form of the command.

[no] encapsulation {frame-relay|ppp|hdlc}

This section provides show and debug commands of the serial synchronous interfaces.

1. Connect to the NIM console using Telnet or Secure Shell (SSH) and open a session to the device using the hw-module session slot/subslot command in privileged EXEC mode.

   To exit the session, press Ctrl-a and Ctrl-q from your keyboard.

2. show platform hardware subslot slot-number module device ge-stats

3. show platform hardware subslot slot-number module host-if status

4. show platform hardware subslot slot-number module host-if statistics

5. show platform hardware subslot slot-number module device ?

   • help: the current information

   • scc-info: module serial information

   • scc-stats: module serial stats

   • scc-stats-p<x>: module serial port stats

   • ge-info: module ge information

   • ge-stats: module ge stats

   • fpga: module fpga information

   • fpga-p<x>: module fpga port information

   • fc-p<x>: module port flow control information

   • mempool: module mempool information

6. debug hw-module subslot slot-number ?

   • commands: Control plane configuration and commands

   • errors: Error handling and race conditions

   • events: Control plane event notifications

   • ha: SPA Specific HA

   • interrupts: Interrupt handling

   • obfl: SPA Specific OBFL (on-board failure logging)

   • oir: SPA OIR information

   • periodic: Periodic processing (for example, plugin_one_sec)

7. show monitor event-trace spa all

8. Use show diag subslot slot-number eeprom detail to check NIM eeprom contents

The asynchronous serial interfaces support the following serial encapsulation methods:

• Block Serial tunneling (BSTUN)

• Raw socket TCP (Raw-TCP)

• Raw socket UDP (Raw-UDP)

• SCADA

Use the following command to configure asynchronous serial encapsulation. To remove the configuration, use the no form of the command.

[no] encapsulation {bstun|raw-tcp|raw-udp|scada}

Example

Router(config)#interface Serial0/3/0
Router(config-if)#physical-layer async
Router(config-if)#encapsulation raw-tcp
Router(config-if)#end
Router#show running-config interface Serial0/3/0
Building configuration...

Current configuration : 89 bytes
!
interface Serial0/3/0
 physical-layer async
 no ip address
 encapsulation raw-tcp
end

Router# 

Encapsulation methods are set according to the type of protocol or application you configure in the Cisco IOS software.