Information Technology Reference
In-Depth Information
Figure15-4 show controllers mci Command Output
Electrical interface identified as type
UNKNOWN, suggesting a hardware
failure or improperly connected cable.
MCI 1, controller type 1.1, microcode version 1.8
128 Kbytes of main memory, 4 Kbytes cache memory
16 system TX buffers, largest buffer size 1520
Restarts: 0 line down, 0 hung output, 0 controller error
Interface 0 is Ethernet1, station address 0000.0c00.3b09
22 total RX buffers, 9 buffer TX queue limit, buffer size 1520
Transmitter delay is 0 microseconds
Interface 1 is Serial2, electrical interface is UNKNOWN
22 total RX buffers, 9 buffer TX queue limit, buffer size 1520
Transmitter delay is 0 microseconds
High speed synchronous serial interface
Interface 3 is Serial3, electrical interface is V.35 DTE
22 total RX buffers, 9 buffer TX queue limit, buffer size 1520
Transmitter delay is 0 microseconds
High speed synchronous serial interface
Using debug Commands
The output of the various
debug
privileged exec commands provides diagnostic information relating to
protocol status and network activity for many internetworking events.
Because debugging output is assigned high priority in the CPU process, it can render the
system unusable. For this reason, use
debug
commands only to troubleshoot specific
problems or during troubleshooting sessions with Cisco technical support staff. Moreover,
it is best to use
debug
commands during periods of lower network traffic and fewer users.
Debugging during these periods decreases the likelihood that increased
debug
command
processing overhead will affect system use. When you finish using a
debug
command,
remember to disable it with its specific
no debug
command or with the
no debug all
command.
Caution
Following are some
debug
commands that are useful when troubleshooting serial and WAN problems.
More information about the function and output of each of these commands is provided in the
Debug
Command Referenc
e publication:
debug serial interface
—Verifies whether HDLC keepalive packets are incrementing. If they are
not, a possible timing problem exists on the interface card or in the network.
•
debug x25 events
—Detects X.25 events, such as the opening and closing of switched virtual circuits
(SVCs). The resulting cause and diagnostic information is included with the event report.
•
debug lapb
—Outputs Link Access Procedure, Balanced (LAPB) or Level 2 X.25 information.
•
debug arp
—Indicates whether the router is sending information about or learning about routers
(with ARP packets) on the other side of the WAN cloud. Use this command when some nodes on a
TCP/IP network are responding, but others are not.
•
debug frame-relay lmi
—Obtains Local Management Interface (LMI) information useful for
determining whether a Frame Relay switch and a router are sending and receiving LMI packets.
•
