Infrastucture design philosophy

Unanswered Question
May 10th, 2010

I'm in the midst of providing network hardware specs for a new facility and had a question for the community regarding design philosphy.

Back in 2000, we rolled out a completely new infrastructure when we moved to VoIP and utilized a 6506 w/ a SUP1A and X6348 modules as the core piece of hardware in our server room.
We deployed stacks of 3524XL-PWR switches to the other two floors of the facility.

The date and the not-yet-standard PoE spec used by Cisco limited what choices we had regarding switches.

Fast forward to today, with switches like the stackable 3750E's providing a lot of bandwidth and features.
I've already bought several 3750E's to replace some of the dying 3524's, but I'm trying to decide whether to simply rely on stacks of 3750's for all locations in the new facility or to implement any of the 6500 or 4500 switches in the core of the facility.

We will be deploying gigabit to the desktop, and I'm seriously considering 10Gbe for the inter-cluster connections.

I have this problem too.
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Leo Laohoo Mon, 05/10/2010 - 20:13

What is your design all about?

A 3500XL is a layer-2-only switch.  If you want to replace the 3500XL then your option is the 2960S (layer 2) and the 3750/3750E/3750X series (multi-layer switch).

GRANT GATHAGAN Mon, 05/10/2010 - 20:53

This is for a brand new infrastructure; design-from-scratch.

I mentioned the 3524 as an example of what had been available in the past, prior to when gigabit to the desktop was common.

At that point in time you had to have a 6500 or 4500 series switch to provide any amount of real horsepower or layer 3 capabilities.

Those switches will not be involved in the new setup.


Since the newer switches have extensive layer 3 capabilities and far more horsepower, I wonder if it's worth putting money into modular series of switch.

Historically, one of the reasons for using modular switches is to allow flexibility and the ability to incorporate newer technology as it becomes available.

In my experience, however, the cost of upgrading a modular switch tends to outstrip the effectiveness of that approach.

Take my 6506, for instance. Since it's not an E-series switch, I'm not sure a SUP720 engine can even be installed in it.
The last time I looked at it, I believe it was around $80K to upgrade it with four gigabit PoE switch modules, SUP720 and the other necessary components.

Contrast that with under $70K for a 48-port 3750E with an EMI image and three 48-port 3750E's with SMI images.

Then you factor in stuff like the 6506's twin 2500W 220v power supplies and the physical space/weight between the two approaches.

Jon Marshall Mon, 05/10/2010 - 21:27

Grant

Take my 6506, for instance. Since it's not an E-series switch, I'm not sure a SUP720 engine can even be installed in it.
The last time I looked at it, I believe it was around $80K to upgrade it with four gigabit PoE switch modules, SUP720 and the other necessary components.

You don't need an E-chassis to run the supervisor 720. However as you say you would need to look at the power supplies, would certainly need a new FAN + to take advantage of the additional throughput you would need to upgrade to fabric enabled/fabric only linecards.

It really depends on features/functionality you need. If you are simply looking for horsepower/throughput and the 3750s meet those requirements then it may well be worth simply using switch stacks for your environment. But the 6500 has more functionality than the 3750 switches both in the base IOS and in the modules that can be inserted into the chassis eg. FWSM, ACE module. If you don't need any of this then fine but you need to make sure there are no limitations with the 3750s that can bite you later on.

It's a tradeoff. With the 6500 you already have and it's supervisor/modules you may as well write it off because virtually all of it needs upgrading and the thing you can keep ie. the chassis is not where the cost lies. So you need to treat it as a new network in terms of hardware, draw up the list of features/throughput you need and if the 3750s match then it would be hard to argue against that.

Personally i think the 6500 is a great switch to act as a distro/core device and there does come a point, both in price, future scalability and features where it makes sense to deploy them.

Jon

Leo Laohoo Mon, 05/10/2010 - 21:37

Take my 6506, for instance. Since it's not an E-series switch, I'm not sure a SUP720 engine can even be installed in it.

Sup720 can support 6506 (plain).

Since the newer switches have extensive layer 3 capabilities and far more horsepower, I wonder if it's worth putting money into modular series of switch.

If you have the right funds, then it's worth investing the plain layer 2 IOS image and upgrade to layer 3 IOS image later when required.

Contrast that with under $70K for a 48-port 3750E with an EMI image and three 48-port 3750E's with SMI images.

Model Comparison Guide Cisco Catalyst 3750-X Series Switches
http://www.cisco.com/en/US/products/ps10745/prod_models_comparison.html

You can also mix a stack with 3750, 3750E and 3750X.

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