Stackables versus 6500 in the core

Unanswered Question
Apr 17th, 2008

I am moving my company to a new building. We are leaving all the old network equipment behind and building out a new network. My question is what is the advantages/disadvantages to using stackables in the core versus a 6500? I only need about 6-10 10GB uplinks to the closets and maybe 40-60 ports in the core for servers, etc. I wont need PoE in the core, and will have seperate routers, firewalls, and APs, so I wont need to put those into a chassis. It seems cheaper and simpler to just have 3750E for all my LAN switches. i can have one or 2 on the shelf for replacement and save more on maintenance. Am I missing something by not going for the 6500's?

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Joseph W. Doherty Thu, 04/17/2008 - 16:15

You've already touched on one difference, the 6500 offers many more interface types and can use embedded service modules not available on the 3750-E.

The 6500 can provide more performance and a higher 10 gig port density, especially with the latest 10 gig 16 port cards.

The 6500 feature set is a bit richer than the 3750-Es, and also has a longer history behind it.

The 3750-E series is likely less expensive, especially compared to a 6500 with a dual sup. (BTW: believe there's currently "aggressive" pricing of the 3750-E POE models, something to consider even if you don't need POE ports.)

PS:

You mention using 3750-Es for all your LAN switches. Depending on need, don't overlook the lesser 3750 and the fact you can mix them and the 3750-E within the same stack.

For your size, you might also want to look at the new 4900M for a core device.

ciscograyaw Thu, 04/17/2008 - 16:37

Our general cutoff is 5 stackables - any more and we tend to go with a chassis. The reasoning:

1) The price difference shouldn't be too much - the main killer is the 10 gigabit line cards require a Sup 720, which is quite expensive. Then again, the 48 port 3750Es are quite expensive as well.

2) Each 3750E only has 2 10 gig ports, but you're only needing 60 copper ports. At that point, you're buying 3750Es just for the extra 10 gig ports. Having to buy an extra 3 3750Es just for 10 gig ports is an expensive proposition.

3) The power redundancy situation on the 6500 is better than the Es. Essentially for redundant power on the 3750Es you will need 1 RPS 2300 for every 2 (for full redundancy i.e. power-circuit or UPS failure). With the 6500s, you just have the two power supplies, and we normally either feed to separate UPSes or one to a UPS and one to wall power (depending on the money we can spend).

4) We, personally, have had a troubling high failure rate on the 3750s (and esp. the Es) so we're a bit weary of them.

Things to consider for the core:

1) Power redundancy - Losing your core because you lost a power supply sucks.

2) Switch redundancy - I have to be able to upgrade/maintain my core without taking it down. So your options are to have 2 core devices or a chassis with red. sups. Given the choice, I go with the latter. But it sounds like you're running/considering a collapsed core so you probably don't want the servers going down during upgrades. So you either team them for dual core (switch) devices and double your port consumption or go with the dual sup chassis.

@josephdoherty - Mixing non-Es in with Es in the stack drops stackwise plus and the stack throughput goes to 32 Gbps.

Joseph W. Doherty Fri, 04/18/2008 - 08:27

"@josephdoherty - Mixing non-Es in with Es in the stack drops stackwise plus and the stack throughput goes to 32 Gbps."

Correct, also negates other Stackwise Plus features such as "StackWise Plus supports destination striping, unlike StackWise support of source stripping", but with retirement of the 3750G-16TD, only way to get 10 gig into a 3750 stack.

Joseph W. Doherty Fri, 04/18/2008 - 08:58

Yes, that and the fact they offer the 3750G-12S, but none with 24 or 48 SFP ports and even less in the 3750-E series. My guess is they don't want to compete to closely against other products within their product line. Otherwise more would ask why not use a stack vs. the 4500 or 6500. With the 3650/3650-E series, or the 4900 series, you're very limited to port density within a single device.

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