[c-nsp] Stacking 3750X vs diverse 4948E

[Nick Hilliard]

On 19/05/2012 09:11, Alexander Lim wrote:
> When doing IOS upgrade, you need to reboot the whole switches in the stack. 

yes - and this can cause unexpectedly long outages during your maintenance
windows.  I've found the stacking to be very reliable in general, but the
upgrade hit is bad news particularly if the code upgrade includes microcode
and bootloader upgrades:

http://puck.nether.net/pipermail/cisco-nsp/2010-December/075697.html

Because of the hit associated with this, I've destacked several existing
stacks and am not planning to use this feature in future.  Your network
requirements may be different though.

Nick


> Regards,
> Alexander Halim
> 
> On May 19, 2012, at 5:00 AM, Keegan Holley <keegan.holley at sungard.com> wrote:
> 
>> The 3750X is relatively new so I've only seen a few of them.  Stackwise in
>> general is pretty solid.  I've never seen a whole stack fail.  If a member
>> fails the stack just keeps going, if the master tails a new master is
>> elected.  One thing to watch out for is the fact that the 3750X isn't
>> intended to be a high performance DC switch.  I have seen issues with queue
>> drops because of small packet buffers on the non-X version which leads to
>> trouble if you do alot of 1G at line rate.  I haven't checked the X series,
>> but I'm told it's not recommended for high performance environments either.
>>
>>
>> 2012/5/18 David Coulson <david at davidcoulson.net>
>>
>>> In a datacenter environment, we typically deploy 4948 top-of-rack switches
>>> with L2 uplinks to our 6500 core - Systems get connections into two
>>> different switches and rely on OS NIC bonding (mostly Linux) to support
>>> switch failures. Switches running STP and in the last four years we've had
>>> no issues with this design (including failures of systems connected to
>>> diverse switches).
>>>
>>> A new proposed configuration utilizes stacked 3750X switches, where
>>> servers would be connected to multiple switches within the same stack. I
>>> have next to no experience in the low-end switches that do stacking, but
>>> from a general risk management perspective, it seems like a many eggs and
>>> single basket configuration.
>>>
>>> Does anyone have any solid experience with 3750X switches, or stacking in
>>> a datacenter in general? I've seen plenty of stacks for closets/end-users,
>>> but I don't see many in a top-of-rack config. Is Cisco stacking typically
>>> 'reliable', in that when a switch fails it will leave the remainder of the
>>> stack functional? What about a software issue? Does the whole stack crap
>>> out and reload, or does the master just fail and a new one get elected?
>>>
>>> I realize it's a pretty broad question, but it boils down to - Is a
>>> stacked switch config significantly less reliable/resilient/available than
>>> two TOR switches?
>>>
>>> David
>>>
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