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Catalyst Switches

Recovering Catalyst Fixed Configuration Switches from a Corrupted or Missing Image

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Nexus 3000 Switches

If for some reason a Nexus 3000 switch is stuck on loader prompt, then reviving process is in order. Similar to Catalyst lines, Nexus models comprise of three components in regards of reviving. One is the kickstart image, two is the main image, and three is the license file. You also need cables (straight-trough patch cable and console cable) and TFTP server in order to handle the reviving process.

The concept of having kickstart and main images are similar to legacy Cisco equipments (i.e. switches, routers), which the kickstart image is the basic boot image and main image is the actual image. In planning of reviving, you must have the following

* Both kickstart and main images
* Both kickstart and main images are stable and are of the same version

An example is a Nexus 3048 model with n3000-uk9-kickstart.5.0.3.U2.1.bin as the kickstart image and a n3000-uk9.5.0.3.U2.1.bin as the main image.

Steps to Revive

Phase 1: TFTP boot

1. Verify that you have the following in working order

* Kickstart image
* Main image
* TFTP server
* Straight-through patch cable
* Console access
* Bootflash (the flash memory hardware which resides inside the switch)

2. Ensure the kickstart and main images are stored in TFTP server and set the TFTP server to use the directory or folder which the three files are located.

3. Connect the switch's MGMT port (by the power supply) to the network where the TFTP server resides

4. Configure the switch's IP reachability to be able to communicate with the TFTP server. Following is illustration

* Enter the switch MGMT port's local IP address and subnet mask

* Depending on your network, you may need to define default gateway


5. Boot the kickstart image file from the TFTP server


6. Assuming the TFTP boot is successful, the switch will then have a switch(boot)# prompt

Phase 2: Local boot

1. Issue dir bootflash: command to show the content of bootflash. If the bootflash is empty, then you need to copy the three files (kickstart image, main image, and license file) over the TFTP server.

2. You may need to format the bootflash in case of corrupted condition. This corrupted condition is identified by the result of dir bootflash: command where showing no files but the number in bytes used and bytes total don't match.


Note:
A bootflash format also means erasing entire content of the bootflash, including existing configuration, NX-OS images, and license file. Only to format when you are sure it is necessary.


When (and only when) there is discrepancy between the number in bytes used and total while the bootflash is empty, the following is to show how format to the bootflash.


3. Assuming that you don't see proper two image files (kickstart and main images), you need to copy the files over the TFTP server. Following is an illustration.

* Enter the switch MGMT port's local IP address and subnet mask

* Depending on your network, you may need to define default gateway

* Complete the port configuration

* Copy over the two image files (kickstart image and main image)


4. Verify that both images are in the bootflash


5. See if the switch is able to boot up using the main image


6. Assuming the boot is successful, you may see something like this


7. It is suggested that you enter y and default value, just to get some basic switch configuration.

8. Once the switch is configured, verify the running-config content of the last lines where the kickstart and main image file names are.


9. If you don't see the kickstart and main image file names as part of the running-config, you need to add them.


10. Reload the switch to ensure that the switch is able to boot up normally


Phase 3: License Installation

It is always suggested that you backup the kickstart image, main image, and license file in case of corrupted bootflash. If for some reason you don't have license file, you need to retrieve the file from either Cisco directly or through Cisco's partner. Here is Cisco link of further info.

Obtaining the License Key File
Installing the License Key File

Cisco IOS-XE based switches

In this case, a 3850 switch is used as example.

Cisco documentation
Recover from a 3850 Series Switch Boot Failure


Feedback received on this FAQ entry:
  • this was very helpful. thank you for taking time to put this out. was stuck in a loop with following error n5k bcm_usd hasn't caught signal 11 bcm_usd hap reset on version 5.x. resolved after slow upgrade over tftp to version 7

    2018-09-15 21:32:28 (neitherfree See Profile)

  • hi i am facing the same problem. the nexus 7000 boot from loader> i have follow this step but find error like this : loader> boot tftp://172.16.1.1/n7000-s2-kickstart.6.2.14.bin Found i82576 [3:0.0] at 0x2020, ROM address 0x7d80 Probing...[i82576] Management port Ethernet addr: E4:C7:22:16:D1:A8 Link UP in 1000/full mode Address: 172.16.1.2 Netmask: 255.255.255.0 Server: 0.0.0.0 Gateway: 172.16.1.1 Address: 172.16.1.2 Netmask: 255.255.255.0 Server: 0.0.0.0 Gateway: 172.16.1.1 Address: 172.16.1.2 Netmask: 255.255.255.0 Server: 172.16.1.1 Gateway: 172.16.1.1 Filesystem type is tftp, using whole disk Booting: /n7000-s2-kickstart.6.2.14.bin console=ttyS0,9600n8nn quiet loader_ver ="4.1.9".... ............................................................................... ..............................Retry 1: Congestion or cable issue Retry 1: Congestion or cable issue Retry 1: Congestion or cable issue Retry 1: Congestion or cable issue Retry 1: Congestion or cable issue need your advice thanks

    2016-02-16 01:34:02



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by aryoba See Profile
last modified: 2016-07-22 18:53:41