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New Member

Stacking issues, redux

Hello all!

Well, I passed my CCNA Security last month! Yea, me! I'm starting to work on my CCNP or my CCNP Security...but work issue has popped up that has me once again, asking for help from this wonderful forum

Not being TOO familiar with Stacking...I went ahead and read Cisco's white paper on Stacked Switches. Now, I have an understanding of the stack technology. But, real world is often different than a "white paper". Hence, my questions:

We have a 5-switch stack already in existance on the network. I had looked at it a couple weeks ago, and the stack cables in back were not wired like I thought they should be...so, let's say, from the top...Master switch...then the slave units. StackPort 1 on the Master should go to StackPort2 on the first inline slave..StackPort 1 on the first slave should go to StackPort2 on the 2nd inline slave, and so on. At the bottom, StackPort1 goes UP to the Master StackPort 2. Is that correct?

Now, the stack consists of 5 switches. 4 are Cisco 3750G 48-PS switches. The last one is a Cisco 3750 24 FS (fiber switch).

The priority goes from 15 (master) for the top switch, then 14, 13, 12, then finally 11 for this last switch, the fiber switch. All are running the same IOS, which is 12.2(50)SE4.

Now, here's where I'm leery. We need to add ANOTHER fiber switch. It's a 3750 24 FS. It has and IOS of 12.2(37)SE, and has no config. If I understand the technology correctly, this should not be a big deal. I should be able to place the switch in the rack, power it up, and then plug the stack cables in similar in pattern to above. Again, if all goes well...the MASTER should see this switch, and should automatically give it a. the later IOS, and b. give it the config. But with it being a 24 port fiber switch, will it automatically configure this new switch for use of the fiber ports? I'm guessing "yes".

Will there be any true need to power off the stack? This is hot-swappable, correct? I know you can hot-swap the stack cables...

Finally, what determines the election of the master/slave? Is it possible that this new switch can somehow become the "Master"? I know when I do a "sho switch" on the new switch, it is showing it as "Master" with priority 1; I'm guessing that since it's priority 1, it will become the slave. I just see visions of VTP screw-ups in my head...

Thanks in advance!

Everyone's tags (3)
2 ACCEPTED SOLUTIONS

Accepted Solutions

Re: Stacking issues, redux

First of all congratulations.

Second, your stack cabling is correct. Here is another possible configurations:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/hardware/quick/guide/3750GSG3.html#wp53466

Stack cabel is hot-swappable, but you need to add new switch first, connect new cables and then power-on it:

https://supportforums.cisco.com/thread/163113

But before that you need to provision new switch into configuration:

switch 6 provision ws-c3750-24fs (or something like this - I mean model number).
Also you can assign the priority to the new switch:
switch 6 priority 10

The election of the master switch is determined by priority, but if you power on one of the low priority switches early enough - it will become master instead of higher priority switches. Preemption will not occur:

https://supportforums.cisco.com/thread/2101511

HTH. Please rate if it was helpful. Thank you.

Re: Stacking issues, redux

you need to enable

boot auto-copy-sw

but I prefer  to manually copy new software to the flash of the new switch before placing it to the stack.

To look for the 4th switch flash you need to execute show flash4:

Another possible solution is to copy new softare image to the added switch manually:

copy flash:c3750-bla-bla flash4

HTH. Please rate if it was helpful. Thank you.

4 REPLIES

Re: Stacking issues, redux

First of all congratulations.

Second, your stack cabling is correct. Here is another possible configurations:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/hardware/quick/guide/3750GSG3.html#wp53466

Stack cabel is hot-swappable, but you need to add new switch first, connect new cables and then power-on it:

https://supportforums.cisco.com/thread/163113

But before that you need to provision new switch into configuration:

switch 6 provision ws-c3750-24fs (or something like this - I mean model number).
Also you can assign the priority to the new switch:
switch 6 priority 10

The election of the master switch is determined by priority, but if you power on one of the low priority switches early enough - it will become master instead of higher priority switches. Preemption will not occur:

https://supportforums.cisco.com/thread/2101511

HTH. Please rate if it was helpful. Thank you.

New Member

Re: Stacking issues, redux

Eugene or others...    

So, reviewing...I had two 3750 48 port copper switches...and 1 3750 24 port fiber switch. All were stacked. Everything working fine.

I then added the 2nd 3750 24 port fiber switch. I had it powered off. I plugged in stack cables..then powered on switch. The IOS on this new switch was 12.2 (37), and the IOS on the Master and other switches was 12.2 (50). So, I would have thought that the Master would see the new switch, and give it the config and the updated IOS.

I made sure that I provisioned the new switch as switch 4, with priority of 12.

When I do a show switch, here is what I get:

*1     Master      xxxx.xxxx.xxxx     15     0     Ready

2     Member    xxxx.xxxx.xxxx     14     0     Ready

3     Member    xxxx.xxxx.xxxx     13     0     Ready

4     Member    xxxx.xxxx.xxxx      1     0      Version Mismatch

I saw the election attempt to take place. The Master saw the new switch; it then said that the auto-something did not find the software, and it aborted. I know have this version mismatch. What is the problem?

When I do a dir flash, this is what I see:

c3750-ipservicesk9-mz.122-50.SE4.bin (the IOS)

vlan.dat

private-config.text

config.text

multiple-fs

So, the IOS is there. Doesn't the MASTER take a copy of the IOS and load it into the slave?

Is there a command I need to issue to make this happen?

Re: Stacking issues, redux

you need to enable

boot auto-copy-sw

but I prefer  to manually copy new software to the flash of the new switch before placing it to the stack.

To look for the 4th switch flash you need to execute show flash4:

Another possible solution is to copy new softare image to the added switch manually:

copy flash:c3750-bla-bla flash4

HTH. Please rate if it was helpful. Thank you.

New Member

Re: Stacking issues, redux

Wow..

Right before I got this from Eugene, I had found the Cisco info on troubleshooting stacking....

I learned about how to see the flash in EACH switch via the dir flash#:

And, I learned if the auto doesnt work, you can manually move the copy via the copy flash:blah blah blah flash4:blah blah blah

But, the boot auto-copy-sw..is that loaded in the master switch's config? If so, then I have a totally new perspective on the so-called "expert" that we took over for at this place.

Heck, I'm almost a master stacker!

But this was great! I logged in remotely, copied over..and I also did the

reset-device4 ( I think that was the command..it wasnt reload..it was so Cisco to make it different than normal). I erased the old IOS off switch 4, reset it...and when it came back up, it was accepted with loving arms into the stack!

THanks Eugene!

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