What the difference between Catalyst 3750-X and 4948-10GE?

wider · ‎06-07-2011

Hello community.

I want to choose a pair of switches for our data center.

What I need:

48 x 1GE access ports, 2 x 10GE uplink ports.

Nice feature of 3750-X is stacking. So what features has 4948-10GE? Why I should prefer that switch?

Joseph W. Doherty · ‎06-07-2011

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Posting

Well the 4900 series is derived from the 4500 series, so the IOS has a little more history to it, also it might differ in some features, for example the 4948 offers, I think, DBL. The 4948 is also a bit more industrial strength offering support for more vlans, more routes, etc. You can find these differences if you review their datasheets.

Leo Laohoo · ‎06-08-2011

Here's the deal. Either model is sufficient for any application but know some "gotcha".

3750 series switches has one small limitation: If you 3750 has more than six switches then I'd recommend you re-design the network. When a stack reaches more 6 and more switches sometimes you will see backplane "lags". These lags happen when you are entering command and can be a heart-stopping (literally!) when you are in configuration mode.

What are you planning to design with your DC? Can you elaborate further?

Joseph W. Doherty · ‎06-08-2011

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Posting

Leo, just curious, have you seen what you describe on original 3750 series (Stackwise) or the -E/-X series (Stackwise+), or both? Reason I ask, besides the difference in bandwidth, the latter is "smarter" about how it manages its ring bandwidth.

PS:

Besides config lag, did there appear to be any impact to traffic forwarding?

Leo Laohoo · ‎06-08-2011

Hey Joseph,

Both the plain and "E". I haven't tried (and I don't want to know) about stacking an "X" beyond 6.

Besides config lag, did there appear to be any impact to traffic forwarding?

I don't remember because I was too busy cleaning the underside of my pants.

Vasiliy Rudomanov · ‎07-16-2012

Ok, what I want is 24 GE non-blocking ports with enough uplink bandwidth.

Two 3750-X (has wide switching capacity) with 24xGE and 2x10GE (with stacking each other) is very cool fit to my requirement.

Why I should consider to choose two 4948-10GE instead of those? Price for 4948-10GE is twice more, but the switch has the same (or equal) switching capacity and has no stacking! Why 4900s costs more?

Joseph W. Doherty · ‎07-16-2012

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The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Vasiliy Rudomanov wrote:

Why 4900s costs more?

Because it's a "better" L3 switch.

Why I should consider to choose two 4948-10GE instead of those?

If a "better" feature is critical to your needs.

For example, recently I'm involved in IPv6 roll-out where IS-IS will be used for routing. That capability is not available on the 3750-X.

Leo Laohoo · ‎07-16-2012

Need to ask what you are trying to achieve.

I've posted this several times (please ignore this if you've seen this before).

Look at the costing. There are some cases when if you are trying to purchase three (or more) 3750X, as a single stack, it's cheaper just to get a 4510R+E with Sup7E card.

IF this is going to a DC application, what are you trying to do? This is because the 3750X has a 32 Gbps (full duplex) backplane. So you need to factor this in if you are having multiple switches in a stack and multiple uplinks (etherchannel).

What are you trying to aggregate? 1 Gbps? 10/100 Mbps?

Vasiliy Rudomanov · ‎07-17-2012

Ok, looks like very logical approachment - "better" because it is better!

I almost agree 4948 is better than 3750-X but I want to know what exactly better and how I can use the better thing in my environment.

I do not use routed and routing protocols at access layer switches, so IPv6 or IS-IS is not my goal.

I do want use stacking but only two switches in stack for hardware redundancy.

I read "http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/data_sheet_c78-584733.html" where they said "Cisco StackWise Plus technology for ease of use and resiliency with 64 Gbps of throughput", so it migth mean 64 Gbps half-duplex, once you said about 32 Gbps full-duplex, but it is not problem in my way when I want to use only two switches using stack backplane.

What I need - I had 70 dual-port GigabitEthernet servers. I should use maximum troughput from all GE interfaces.

I choose 24-ports 3750-X with two 10GE uplinks (two in stacks), so I have near wire-speed troughput to my VSS core.

The 4948-10GE and 3750-X has the same forwarding rate - 65.5 mpps, so in my case I consider I have no cause to choose 4948-10GE.

Am I right?

Leo Laohoo · ‎07-17-2012

The 4948-10GE and 3750-X has the same forwarding rate - 65.5 mpps, so in my case I consider I have no cause to choose 4948-10GE.

Am I right?

If you have 70 servers with dual ports (how about the ILO/DRAK) then 4948 is not enough because you can't stack it.

Are you sure you have 70 servers and nothing MORE? I mean, going back to my previous post, check the costing of the 4500R+E with Sup7E against multiple switches in a stack for a 3750X solution. Yes, the 3750X has a 32 Gbps (full duplex) backplane but the 4500R+E and Sup7E has 40 Gbps (full duplex) backplane per slot. Your oversubscription rate just went down significantly.

HOWEVER, I'm not sure if 4948 WILL support VSS. In the next few months (around end of 2012 or mid-2013), Cisco will be releasing a brand new train of IOS that will allow Sup7E (for the 4500R+E and the 4500X) to support VSS. Since the 4948-10GE is a Sup5 or Sup6, I'm not certain it will or can support VSS.

Vasiliy Rudomanov · ‎07-18-2012

I have 70 servers with dual-ports ethernet and iLO ports as well.

My option was two pair of 3750-X in stacking of each pair. Stacking will able eliminate cable\NIC issues at a server.

I doubt to do this with 4500R+E, because I have to buy two 4500 chassis and all I can do is NIC redundancy but no load balancing via etherchannel.

Anyway, thank you for you vision. I will consider it for my future projects.

Nowday I choose 3750-X.

hobbe · ‎07-18-2012

I just want to give a small heads up on a couple of things that have not been spoken of in this thread.

First of all the 3750X stacks very nicely, but it still will be brought down by fx a os upgrade or a software glitch.

so treat a 3750x stack just as you would any other switch.

if you need redundancy you would have to build two stacks of 3750x and they do not support vss.

however if i am not misremembering you can connect a stack of 3750 to two nexus 5K and make the etherchannel go to both of the nexus switches and it will work. (atleast that is how I remember it when we did a test 3 years ago or so.)

The other part that i feel needs to be adressed is that this is a datacenter so it might be that speed is of the issue here and I am not talking about megabytes I am talking about latency.

The 4948E is "alot" faster than the 3750x when it comes to latency.

Just some thoughts to add to the other parts.