Howto upgrade IOS on a 3750 switch stack

If you want to upgrade IOS on a 3750 switch stack follow this procedure

There are some new IOS commands to automate upgrading of a stack, but I use the familiar manual method.

All of your stack members really should be running the same version of IOS (even though there’s a chance that if the versions are close enough the stack might still work).

Upgrading a switch is like upgrading a router, really. You put the new IOS on the TFTP server. Make sure there is room for it in the flash of the target device, and tftp it up. When you are ready to start using it, change the boot system command on the device to point to it, and reload.

What makes switch stacks different is that you need to copy the IOS to all of the switches. Here’s how.

1)Log into your stack. (You’ll be logged into the master). Do show stack to find out how many switches are in the stack, and which one is the master. Let’s say there are four switches and the master is 4.

2)Use copy tftp flash: and answer the prompts to get your IOS up there.

3)You can do dir flash: to see that the new IOS is there. When you refer to “flash:”, you are always referring to the master. You can also refer to a particular stack member’s flash like this: dir flash2:. So on this stack, where 4 is the master, dir flash: and dir flash4: will look the same.

4)Now get that IOS image onto the other switches in the stack. You can either tftp it to each in turn with copy tftp flash1: and so on, or use copy flash4: flash1:. The copy method is only a little quicker, but it works.

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4 thoughts on “Howto upgrade IOS on a 3750 switch stack

  1. I have a question regarding this topic. ‘howto update IOS on a 3750 switch stack’. I have copied the IOS to the master and member switches. boot flash is using new IOS, but when the reload command was issued only the master was upgraded.
    Following the reload with the new IOS on the master, the member switches were not recognized. Disconnected the members and chg’d boot flash on each manually.
    How can this be done automatically?

  2. Before reloading the master, you need to go into config mode and issue the command:

    boot system switch all flash:/c3750-ipbasek9-mz.122-46.SE.bin

    (or whatever IOS you have loaded on each switch. They should all be the same).

    Before you reload, verify the contents of the switches’ flash and that the IOS are all the same, with: dir all

    AND, check each switches’ boot config with: sho boot

    For example they should all read:
    BOOT path-list : flash:/c3750-ipbasek9-mz.122-46.SE.bin


  3. hi julie,

    Please use the .tar file for a stack…it will be more easy to make a stack without headache to think about the MAC addresses for switches.

    Try this command in privileged mode:

    archive download-sw /imageonly tftp:///.tar

    and give a cold restart.

    It will automatically delete the old IOSs from all the switches and restart with new IOSs only.
    Master selection process will also automatically after setting the priority before giving the cold restart and may take sometime around 15 minutes to get all switches back to up state…So be cool and wait for the prompt…

    Ask for more help…

  4. With this command, archive download-sw /imageonly tftp:///.tar , DO you have to have a .tar IOS or will it work with .bin IOS’s?

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