Eight examples of solving router faults

I. cisco2610. Use the erase flash command. Change to rommon after restarting 1> how to restore

I downloaded a c2600-i-mz.121-3.T file, how to transfer it to the router! I am now using the console port to connect) PC requires a tftp server software

How to restore ios:
In the rommon status, enter: case sensitive)
Rommon 1> IP_ADDRESS = 192.168.0.1 (IP address of the router)
Rommon 2> IP_SUBNET_MASK = mask of 255.255.255.0 vro)
Rommon 3> DEFAULT_GATEWAY = 192.168.0.2 gateway, which is the IP address of the PC)
Rommon 4> TFTP_SERVER = 192.168.0.2 is the IP address of the PC)
Rommon 5> TFTP_FILE = Name of the c2600-i-mz.120-7.T.bin Upload File)
Rommon 6> sync save)
Rommon 7> set view)
Rommon 8> tftpdnld Transfer File)
PC settings:
IP address 192.168.0.2
Mask 255.255.255.0
The gateway 192.168.0.1 is the IP address of the router)
2. There are a lot of brothers who have problems upgrading ios. Here is a note for IOS upgrade.

1. Pre-Upgrade: confirm the current system resources, including mem and FLASH.
2. Check the IOS version number and feature set of the current running version. Note that the current version does not contain T, the T series in cisco IOS generally have many new features and support for new hardware. In general, the new features supported by 11.3T will not be merged into the main release version until 12.0. It is important to note that versions of 12.0T can only be merged to a specific version of 12.1, and so on.
3. The main requirement for IOS to be upgraded is mem/flash. Make sure that the current resource meets the requirements of the new version. Confirm that the feature set meets the requirements.
4. Back up the original IOS and configuration files. Make sure there are no errors during the backup process.
5. Upgrade IOS.
6. confirm that the new IOS is written to FLASH.
7. Use boot systemIOS or set boot system (cat OS) to modify the Startup File name. There is a slight difference between different platforms. If there is a previous configuration, no or clear is required)
8. Save the configuration and confirm that the startup parameters are correctly configured.
9. reload.
Iii. CISCO router port status

CSU ── channel server unit, DSU ── data server unit
1. Serial * is down, line protocol is down (DTE)
Faults:
[1] No power is added to the vro.
[2] LINE is not connected to CSU/DSU.
[3] hardware error.
Solution:
[1] Check power supply.
[2] Check whether the cables and serial ports used are correct.
[3] switch to another serial port.
2. Serial * is up, line protocol is down (DTE)
Faults:
[1] local or remote router configuration is lost.
[2] The remote router is not powered on.
[3] line faults and switch faults.
[4] The serial sending clock is not set on CSU/DSU.
[5] CSU/DSU fault.
[6] local or remote router hardware faults.
Solution:
[1] Set MODEM, CSU, or DSU to "LOOPBACK" and run the "show int s *" command to confirm line protocol.
Whether the router is UP or not. If the router is UP, it indicates that the mailbox Bureau is faulty or the remote router has been shut down.
[2] If the remote router fails, repeat step [1].
[3] Check whether the serial port connected by the cable is correct. Use "show controllers" to check which cable is connected to which serial port.
[4] type "debug serial interface". If line protocol does not come up, or the command
Indicates that the number of activated ports does not increase, proving that the router hardware is incorrect. Change the router port if line protocol is UP and
The number of activated ports increases, proving that the fault is not on the local router.
[5] Change the router port.
3. Serial * is up, line protocol is down (DCE)
Faults:
[1] CLOCKRATE in router port configuration is lost.
[2] The DTE device is not started.
[3] Remote CSU/DSU faults.
[4] cable connection error or fault.
[5] router hardware error.
Solution:
[1] add CLOCKRATE to the router port configuration.
[2] set the DTE device to SCTE mode.
[3] confirm that the cables used are correct.
[4] If line protocol is still DOWN, replace the router port.
4. Serial * is up, line protocol is uplooped)
Faults:
If a LOOP exists in the line and the sequence number in the activated software package changes to a random number at the beginning, if the same random number
When the code is returned to the LOOP Line, a LOOP is generated.
Solution:
[1] use the "sh run" command to find LOOPBACK.
[2] use "no loopback" to remove the LOOP.
[3] If PROTOCOL is still DOWN, contact the post office.
5. Serial * is up, line protocol is down (disabled)
Faults:
[1] Postal Bureau fault.
[2] CSU/DSU hardware faults.
[3] router hardware faults.
Solution:
[1] Find the dual-state component signal of CTS or DSR.
[2] using CSU/DSU as loopdte loop). If the fault persists, it may be a hardware fault. If the fault stops, it indicates that it is a mail
Power Bureau fault.
[3] replacing the faulty hardware.

6. Serial * is administratively down, line protocol is down
Faults:
[1] PORT may be shut down.
[2] duplicate IP addresses.
Solution:
[1] use the "no shutdown" command to remove SHUTDOWN.
[2] change one of the duplicate IP addresses