Replacing 2 x 3750s (stack)

[Andy White]

Hello,

I am replacing 2 x 3750s which are stacked with 2 x 3750Gs.  I have set them up the same and they are racked underneather the current live ones.  Now these switch hang off out Cisco ASA 5520s so we have the Internet, WAN, DMZs all hanging off these 2 switches.  Would you look for out of hours downtime, or do something fancy like trunk (etherchannel) the 2 stacks and migrate slowly.  The reason I ask is I can only do this over a weekend and I can't pop in for weeks so thought there maybe a way to move gradually?

Thanks in advance

Andy

[Leo Laohoo]

The easiest way I can think of this this ...

Join the 3750G to the stack.

Configure the 3750G's ports EXACTLY like the 3750 ports.  Move the physical connections from the 3750 to the 3750G (including etherchannels) until no other connection terminates to the 3750.

Power down the 3750 and remove from the stack.

Renumber the 3750G to become switch 1 and 2 respectively.  Change the switch priority to minimize bootup time and stack election.  Reboot.

Remove excess configuration about switch 3 and 4.

[Andy White]

Only issue I guess is one stack is on 12.x and the other is on 15.x, do they have to be the same?

[Leo Laohoo]

do they have to be the same?

The entire stack must be running the same IOS versoin and the same Feature Set.

Do the migration first and then you can upgrade the IOS.

If you want to run 15.X, make sure you disable all SNMP traps. 

[Andy White]

Thanks, how do I disable all SNMP traps?

[Leo Laohoo]

The command is "no snmp-server enable traps".