Tonight, I was tasked to work on a 3750 switch stack (of 4 total). One of the switches had a port that had gone bad, and the customer wanted to have this replaced. With me here in Alabama, and the customer site in New Jersey, I had a guy from the customer side do the physical work, while I did a webex session and did the command line work. Not much to the switch stack side, you just have to know what to do. So, with that said, I thought Id write about the proper procedure for replacing a switch in a 3750 stack.
First and foremost, the switch has to be of the same hardware and same IOS as the master switch. I say the same IOS, but in the Cisco documentation, it says the same or better. Well, I found that not to be true. The replacement switch we got from Cisco came with a 122-35 image, while the production switches had a 122-25 image on them. According to the documentation, the new switch was "supposed" to get the image off the master, but it didnt. I had to separate the switch and tftp the image (and delete the newer one) off the replacement switch so it would become part of the stack. This is what I got when I put the replacement switch in BEFORE putting the same image on it:
Switch# show switch
Current
Switch# Role Mac Address Priority State
--------------------------------------------------------
1 Slave xxxx.xxxx.7300 1 Ready
2 Slave xxxx.xxxx.f480 1 Version Mismatch
*3 Master xxxx.xxxx.1580 1 Ready
4 Slave xxxx.xxxx.0480 1 Ready
Ah, "Version Mismatch"? Well, I waited, and nothing ever happened. I waited a little longer, and it never got its image from the master like the documentation stated. Well, thats when I just went and tftp'ed the image on myself. I took it out of the stack, put a temporary IP on it, and put the image on. Then, after deleting the newer image, I went through the process to get it in:
1. With the power off, put the switch stack cables in place.
2. Power the switch on.
Easy as that to get the stack going. No configuration that has to be done at all. Its all in the stack cabling to get the stack going (unlike Brocade where you have several commands to get this up). Once the stack was in place with the new switch, here is what a "show switch" looks like:
Current
Switch# Role Mac Address Priority State
--------------------------------------------------------
1 Slave xxxx.xxxx.7300 1 Ready
2 Slave xxxx.xxxx.f480 1 Ready <--- New switch
*3 Master xxxx.xxxx.1580 1 Ready
4 Slave xxxx.xxxx.0480 1 Ready
