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I am just wondering if it's possible to stack Cisco 3750 switches using their ethernet interfaces? I don't have the proprietary stacking cables.

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  • What are your goals with the stack? Single management interface or the bandwidth of the switch ring? – generalnetworkerror Jul 13 '13 at 7:48
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    The stacking cables can be bought off ebay for just over £10 a pop. You'll need to for a full-duplex 2 switch stack – mellowd Jul 13 '13 at 8:39
  • @mellowd +1, or ask around in local technical forums, chances are someone will give them for free, we have big cardboard full of them (12S was 3750 only, no 3560 model, as we don't like stacking). – ytti Jul 13 '13 at 17:18
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Jan 5 at 2:30
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Unfortunately, you'll need the StackWise cables to stack 3750's. (And the StackWise modules as well depending on your switches.)

See this Cisco white paper on Cisco StackWise for more information.

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Like @Brett said, StackWise is not possible without the use of stack ports.

However, there is also really really old Cisco switch feature called cluster which uses just ethernet ports.
I personally would never run this cluster feature and would steer away StackWise as well unless I have extremely good justification for it.

Usually higher software complexity means lower MTBF and that is my experience running tens of 3750 stacks and hundreds of individual 3750 switches.
The newly introduced 3850 stack architecture seems much more appealing, as it's more closely designed to look like chassis based switch, you have two RPs and bunch of dumb linecards. But of course experience is thin on such a new solution.

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  • Upvote for the cluster mention for management and I'm in complete agreement with Ytti that simple -- and isolated -- designs are better toward MTBF. – generalnetworkerror Jul 13 '13 at 7:50
  • @ytti - I agree with you, based on my own annecdotal evidence, but are you aware of any studies showing the link between stacking and lower MTBF? – Brett Lykins Jul 13 '13 at 19:55
  • @BrettLykins mine is anecdotal as well, we have good number of stacks and higher number of non-stacks, and we've had several stack-specifics issues bringing whole stack down. But it's still probably not statistically relevant. It seem logical to assume that adding more software features exposes you to higher amount of software defects. – ytti Jul 13 '13 at 20:01
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As @Brett said, StackWise cables are required. Depending on what your goal is for the stack, you may be fine just creating an port-channel (Etherchannel) using up to 8x100Mb (800Mb) or 8x1Gb (8Gb) between 3750 switches. If you have certain 3750 models with 10/100Mb ports and 1000Mb uplinks, you could channelize up to 4 ports to get 4Gb.

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    It is not one management interface to all switches, which is one of the nicest benefits of the stack – Mike Pennington Jul 13 '13 at 9:05

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