tec Tip Videos

Cisco 3750 Switch Stacking

Nathan explains the factors involved with stacking Cisco 3750 switches.


Hello I'm Nathan, and today we're going to be talking about 3750 switch stacking. I have a diagram crudely drawn up here for your perusal. Here we have an example of several switches in a stack. A happy face for the happy stack, this is an example of how you would want to cable your stack if it of course were 3 switches high. These stack cables are layered in a way that will allow not only all the switches to be connected to one another, but then to allow the bottom switch to be connected back to the top switch, which is the recommended way to cable these guys together.

You'll notice I have a note here that also says that it can only be 9 high at a maximum. They don't have to be 9 high of course, they can be just 2 switches together, or up to 9. The higher that number grows, of course, the lower the bandwidth will be available to the entire stack, but that's OK. This just keeps you from building the tower of Babel or anything like that, we don't want to go that high.

Down here are some of the caveats, some things to keep in mind. You want your software versions to match on all of these switches. Feature sets can mix, I know that's a misconception, a lot of folks don't even know that that's possible, but the software versions still need to be the same or at least very close together. Another thing, if there's a cable failure anywhere in here, let's say that this cable here were to break for some reason, you'd only have half of the available bandwidth along the stack. That's also something not a lot of folks know, and that stackwise will default to the lowest common denominator.

Where that matters is when you have a mix of hardware, which you can do if you have a 3750, if this were a standard 3750 with a 3750 E and an X down here, you can mix that hardware, but knowing that the newer 3750's have a higher bandwidth stack than the older, you can mix them but they will default to the lowest common denominator, which would be 32 gigs across the stack.

Some frequently asked questions in relation to the stacking model is can I mix stacks? Like we mentioned, yes you can. You can actually mix any of the 3750 standard G, X, or E together from a hardware perspective. Again, it's important that those software versions match. LAN base of course, is not included. That's the one place that they get you, is that if you have a LAN base 3750 X, it cannot mix in a stack with other 3750's. My next question, what about LAN base then? What is the deal there? You can stack LAN bases together, but only with each other.

There is no cable included with the LAN base model 3750 X, that's just because originally when they were first released, stacking was not an option. They later amended that through software, so now you can do it, but you do need to make sure that you include that stacking cable when you place your orders. Is it possible to upgrade from LAN base to either IP base or IP services? Absolutely. There is a way you can do that, and then yes they would be allowed to be stacked with other switches.

Thank you for spending some time with us today. Hope you found it informative. I did promise a happy face, so there it is. There was no math this segment. Please join us again next time.