Large Enterprise Switch vs. Several Smaller Switches

[rpryomski]

What advantages are presented with purchasing one large enterprise switch (like a CAT 6509) vs several smaller switches (like CAT 2950's)

I don't want to get into specific models too much here. But I'm basicly trying to understand what advantages are achieved.

The smaller switches would be in a hub and spoke config (1 Gb connections) with a centeral switch being supporting the 1 Gb connections.

There is obviously a significant cost difference, that being the lager switch is more exspensive.

What does this buy me?

I'd imagine I'm not the only one who has run into this debate. If the cost is lower and you can get reasonable performance, why not go with several smaller switches?

Thanks

[Georg Pauwen]

Hello,

I think the basic approach would be to purchase what you need. A 6509 has a huge backplane capacity and might be way too much for your purposes. On the other hand, the 6509 has some modules (like the Intrusion Detection Module or the Content Services Gateway) which are not available for the 2950...

I worked for a company that had bought redundant 6509 switches, while they would have been fine with 3550s or even 3500XL switches and some low-end L3 device like a 2600 for inter-VLAN routing, they spent way too much money.

The obvious difference is that several 2950s can be moved to different SERs, while the 6509 has to stay in one location, and all the cable runs have to be terminated there.

Regards,

Georg

[chuck.price]

Also look at your cabling distances. If your cable lengths exceed the maximum, you should use smaller switched in a wiring closet and then patch them into a larger swtich.

[ferro]

also u should consider if u ll use vlans... if yes u may need the L3 switch...

[a.awan]

For some people management of the end device is also a factor. A single switch is much easier to manage than multiple smaller switches. I think what you need to do is to work out a standard for yourself that if your port count per closet goes above X port then move from smaller switches to a larger switch like a 4500 or 6500. For smaller switches i will advise getting a model that is stackable and capable of being managed like a single switch (e.g. 3750s).

Redundancy is another factor that comes into play when faced with a decision like yours. If the services you are providing are of extremely critical nature then it is wise to spend a little extra to get a solution support redundant management processors and power supplies per switch and even redundant switches.

All the suggestions posted prior are valid and it will be up to you to judge your own requirement and then decide which direction to take.

[mjcole_mcp]

One management point missed above, that can become a pain with just a few switches is cable management. You are probably going to want to use a whole bunch of different colour cables to mark which ones are uplnk to the core and which cables are "last mile" to the end user. Also make sure your core switch is fast enough... whatever fast enough is for your network.

Do you use MRTG? If not, you may want to have a look at it.

[rmerritt]

It all depends on your wiring scheme requirements and your bandwidth requirements. If all devices in your organization can come to one comm room, you probably do not need a 6500 but a 4506 w/L3 is a nice choice. 2950s best aspect is that only 20+ devices go down if it fails. I have replaced around twenty of these devices over the last 5 years. I personally like the bigger switches but I am in a hospital where bandwidth and high port density rule.

[sextrand]

Like so many design questions, the actual answer to yours is "it depends", but a few things cross my mind.

Given a hub/spoke environement, what you are needing is uplink port aggregation. With your stated goal of 1GB uplinks, a 2950 is not going to provide much of a hub with a maximum of two GB uplinks.

The cabling requirements also drive what you can use as a core switch. If you must use fiber to remote IDF's you need something that can handle multiple fiber ports. If everything is within cat-5 distances, your options open up a bit. Some of the 3700 series switches have 24 10/100/1000 copper ports and 4 SFP based ports. These make nice core switches for small locations that can be done in copper.

If you need a lot of fiber, you are pretty well stuck. The 3550-12G will give you 10 GBIC based ports, but you only have 2 copper 10/100/1000 to use for servers, etc, although there are copper GBIC's available. Bigger than that and you are looking at the 4500/6500 series switches.

One other consideration is reliability. If you are serving a large user community, you may want to consider redundant power supplies, even redundant chassis. Only the larger chassis have the redundant power supplies. Maintenance also factors in. One maintenance contract vs several.

Another issue is management. One large switch is easier to manage than several small ones.

[njacottin]

In my opinion, your choice has to be dependent of your achitechture choice, expected growth (scalability), traffic type & rate, current number of user and the kind of cabling technologies that you intend to use (dependent on machines, floor and campus distances). Don't forget also the level of availability that you want to achieve. This will also help you to choose between stackable and chassis products.

Another important factor is the layer at which you want to work. I mean by this if you want to implement layer 3 routing instead of STP for the interconnections between your different designed blocks (see 'Gigabit Campus Network Design—Principles and Architecture' white paper).

In conclusion, for me it's not always necessary to choose a Catalyst from the 6000 series, if you don't need it. But, I will rather prefer Catalyst 3550 series against a Catalyst 2950 series. They are multilayer capable and don't cost much more.

I hope, my answer will help you.

[david.bradley]

With the larger chassis based switches you are also paying for added redundancy, redundant PSUs and especially if your making use of redundant Sups

[b-wilson]

Advantages of a chassis i.e., 6500 are for example port density, management, backplain switching speeds, service available, Layers 2-7 compared to L2 on a Cat2950 and most importantly the history of CISCO Systems.

The Catalyst 5xxx Chassis of products was around for years and years and supported constantly...even after end-of-manufacture, where as SMB Switches 19xx, 2900 once they reach end of life you literally throw it out as no development will be supported afterwards.

Stackable switches such as Catalyst 3750-L3 would be a better option and has a major advantage over 2950's.

Also look at Catalyst 4500's as an option.

Hope this helps.