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3750 stack unit replacement procedure

I have a switch stack consisting of one 3750-24TS-S and one 3750G-24-S. Originally each unit was configured with a name and a management IP address, then the two units were connected via the stacking cable(s). No other configuration was done; this is just a plain vanilla backbone.

When viewed through Cisco Network Assistant the stack appears as one unit. I try to always boot the 3650G first, so its name and IP address appears as the stack address. There is very limited information available about the member unit either from CNA or the command line regardless of which console port I connect to (posters here warned me about that before I bought the 3750s; they were right).

I also have an RPS unit connected to the DC input of each switch as a rudimentary redundent power solution.

All working fine, until the AC power supply on the 3750-24TS went bad. The RPS picked up as designed (and I then found that even though the RPS unit weights 15 kg and could probably start my car, it will only supply one unit at a time. Another lesson). Cisco RMA'd me a replacement unit and last night I tried to put it in.

Problem: the replacement 3750-24TS will not operate as part of the stack. If I boot it standalone it comes up, asks for a name and IP address, and then brings all 26 ports up. But if I then connect it to the stack it boots, gets to the show ver equivalent in the boot sequence, and freezes. The two tops status LEDs are green, but all other LEDs are dark and the ports do not come up. This is true whether I give it the same name/IP as the original unit, a different name/IP than the original unit, or just leave it unconfigured when I bring it up in the stack.

I thought to download the saved config via CNA, but there is no way to access the 2nd unit. The only thing I see from the command line is that the 3750G master thinks it has a stacking cable attached, but I can't get anything on the replacement member.

Is the replacement unit bad, or is there another configuration recovery procedure that I need to execute?

Thanks.

sPh

Reply to
sphealey
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If you have SmartNet suppport contract then you shold open a case with the Cisco TAC

Reply to
Merv

Technically this is still a severity 3 case [and will be until the original unit's DC power goes bad too ;-( ] so TAC is not bending all their top resources to it at the moment.

sPh

Reply to
sphealey

In what way is it severity 3?

You need to ask yourself the following questions.

Is the network down? Am I prepared to work 24x7?

P1.

I have not done much with the 3750 but I did a bit a while back.

  1. Try to get a good config off if you need it without the new one in the stack. I am not sure but I feel that it may be at risk.

  1. You need I think the same softwaer version on the members before bringing them in to the stack.

  2. Stack membership ID is remembered. The first member is 1 etc. You can change the number. It is some weird ciommand that took a while to figure out. Oh yes its like:

renumber old-number new-number

Maybe. But it's not renumber I don't think.

Reply to
Bod43

I've seen this where the two IOS's are incompatible. One of the switches should tell you this during boot but I can't remember which switch reports the situation. Try (I hate saying that) booting both switches while stacked and watch both consoles for advice.

Steve.

Reply to
Steve Burton

Thank you very much. The two versions are 12.2(20)SE and 12.2(25)SEB4. Cisco TAC replied that these were fully compatible. Then they tried it in the lab and reproduced my symptoms! So much for the knowledge base.

Current plan is to downgrade the replacement unit, verify that the stack works, then upgrade the whole stack to current. We shall see if that works.

sPh

Reply to
Steven Healey

please post what happens here. I'd really like to know if it works.

Steve.

Reply to
Steve Burton

As you suspected. Both the original and replacement units are now running 12.2(20)SE (after some difficulty until I realized I could give the replacement unit an unused IP address and then connect it FE-to-FE so that I could telnet and tftp) and the replacement unit came up as part of the stack with no errors. TAC had me do one stacking cable, then two, to verify there was no problem with those cables or interfaces.

My next step is to track down the current GD release for that unit and figure out how to upgrade both units without causing a disaster.

Thanks again for your suggestion - it probably saved 2-3 days going back and forth with TAC. That is a good example of why I post here even when I have a case open.

sPh

Reply to
sPh

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