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A rundown on switches

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by shanghai sam

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I know this is a general question, but I'm looking for a comparison between different switches for enterprise use. We've been using 3Com 3300 switches for a while and they've been working OK, but we are in the process of upgrading our entire networkinfrastructure and would like some information on switches. We'd like to know what the advantage is of having a switch with a faster processor (or a processor at all) and why would a switch need more memory, and why such a HUGE difference in prices?

We run a WAN with about 75 remote locations on lines varying from 56k to T1. Any new switches we buy would be for our main location only which has approximately 200 workstations, 50 servers and a mainframe. We would need 100mb ports, although gigabit for things like heavy-use servers and the mainframe wouldn't be out of the question.

Any answer that increases my understanding will receive at least a share of the points. I'll add more points the answers warrant it. Thanks!

12 replies

by timthetoolman

Hi,

In a nutshell, a switch is just like a hub only its selective about which port to send its traffic down - resulting in increased efficiency.

BUT... Switches offer all sorts of other functionality and options including "self learning" so that the switch *learns* the best network path for certain traffic. Simple things like the number of ports available, and the types of protocols that may be passed (UDP for instance) or ability to monitor traffic.

At the end of the day all this is invisible to the user, however. All they want is their data... and they want it reliably and fast.

You need to "know your traffic" to decide whether you need a switch or not (This is General info now... no necessarily for "you") It would be a wasteto put a switch in an office that has several PCs in it where the users do a bit of word processing, read a bit of mail etc...

However, a well placed gigabit switch between a fileserver and application server and database server where there is mucho interaction between the three would be beneficial.

Here are two links to camparisions of switches...

http://networkcomputing.telezoo.com/asp/sc/icsbs.asp?prepagename=SEARCH_BY_BRAND&idCatitems=9171&idCatitems=9971&idCatitems=9198&idCatitems=9192&view=long&history=^709^764^758&cn=NWC80&msghead=Switching+in+the+SAN&msgdtl=If+your+data+system+consists+of+multiple+servers+and+outboard+drive+cabinets%2C+maybe+it%92s+time+to+consider+installing+a+SAN+switch%2E+These+devices+use+gigabit+fiber+ports+and+high+speed+switching+fabrics+to+boost+data+transfer+rates+well+beyond+those+offered+by+SCSI+busses%2E+%3Cfont+color%3Dred%3E%3Cb%3EIn+this+CompareIT+we+look+at+SAN+switch+offerings+from++Compaq%2C+EMC%2C+Qlogic%2C+and++Vixel%21%3C%2Ffont%3E%3C%2Fb%3E

(continued)

by timthetoolman

http://networkcomputing.telezoo.com/asp/sc/icsbs.asp?idCatitems=6119&idCatitems=9369&idCatitems=9325&idCatitems=9399&view=long&idcats=305&history=^709^721^485&cn=002&msghead=Control+Web+Traffic+Efficiently&msgdtl=Cache+Switches+improve+the+efficiency+of+caching+appliances+by+intercepting+web+traffic+bound+for+the+corporate+WAN+and+redirecting+it+to+caching+appliances+for+processing%2E+%3Cfont+color%3Dred%3E%3Cb%3ECompare+and+get+quotes+for+caching+switches+from+Lucent%2C+Foundry%2C+Extreme+and+Nortel%21+%3C%2Ffont%3E%3C%2Fb%3E

(remove spaces from above URLs - and I hope they work!)

And here is a quite good price guide for popular network devices (hubs, routers and switches).

Cheers,
Tim

by maxwell edison

Here are some great Web sites with information that will be helpful.

See this site for an informative presentation on, "Congestion in Network Switches":

http://www.academ.com/nanog/feb1997/gigaswitch/

It includes presentation information onthe following issues:

Congestion in Network Switches

Congestion Defined

Congestion in Switches

Congestion at Output Port

Input Buffering

Output Buffering (2x Fabric)

Buffered packets

Buffering for Bursts

What is HOL Blocking

HOL Blocking

HOL Blocking and Congestion

GIGAswitch/FDDI System

What can be done about Congestion

Alleviating Congestion

Network Congestion - in Perspective

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(continued...)

by maxwell edison

.
.
PC Magazine's comparative reviews:

http://www.pcmag.com/article/0,2997,s%253D1610%2526a%253D17636,00.asp

High End
There's something to be said for products that offer the most features, even if they're pricey. That is surely the case with our Editors' Choice in the high-end category: the Foundry FastIron 4802. This $5,995 switch is actually at the lowest rung of Foundry's large set of enterprise-oriented offerings. The FastIron 4802's comprehensive feature set was matched by its stellar performance, and the switch's Web-based management interface is as much a pleasure to use as it is functional.

Midrange
Almost any small or medium-size organization could build its network around any of the switches in our midrange and high-end categories and get a satisfactory result. That said, we give our Editors' Choice in the midrange to the Cisco Catalyst 2950T-24 ($1,995 list) for the sheer number of enterprise-level features packed into a decidedly low-priced product.

Low End
In the same vein, we award an Editors' Choice to our low-end favorite, the SMC TigerStack II 6624M, which is a real bargain at $699. It's a 24-port managed switch that can be stacked into a configuration of up to 16 units, offering 384 ports. But if management features are superfluous to your needs, go for the D-Link DSS-24+. This unmanaged switch is Plug and Play?simple, and at $249, it's easy on the budget.

That is just a very small segment of the reviews. It provides details and comments dozens of different brands of switches

(REMOVE SPACES from the pasted URLs.)

Best of luck,

Maxwell

by ann777

Switches with faster processors handle the routing of packets quickly and more efficiently than those with slower processors.

Switches remember paths to computers within their subnet. The more memory a switch has, the more information the switch will hold when transmitting packets to individual computers. If the computer does not receive the complete packet, it issues a request for retransmittal. If the switch has enough memory, that packet retransmittal will be handled by the switch with it's memory. If the switch no longer has that info in memory, then it has to forward that request back to the server and the server has to retransmit. That, in non-technical terms, describes why more memory is good.

Pricing is based on a bunch of factors.

There are lots of links out there. The best comparisons cost $'s to receive. www.gartner.com has some; do a search on www.yahoo.com for "switches white papers" to find others.

by ann777

Also, most people do not think about gigabit switches unless they are talking about fiber (or fibre) or a fibre backbone between servers in the computer room.

by jereg

I recently found myself surfing the web for switch info also. I was trying to get ammunition to convince the owner of the company that we needed to move from hubs to switches, and of course why that would be better. In my search, I ended up at Intel's site: www.intel.com
Intel has a lot of very detailed white papers on switching and ethernet technology in general. I learned far more than I neede or wanted to know about switches from their papers. Check them out.
Hope that helps.

by xgenius

Lets see.
Switches do more work than bridges or gateways and need more processing power and may have multiple processors or even run on a microcomputer for better performance.
And hence the higher price.
To give an apples to apples comparison is impossible due mainly to the wide array of them.
Though if you could narrow it down to the two or three you are considering I could help.

by wroming

This can be a rather extensive answer, but here is the basic run down.

The core switch that interconnects all the rest of the network needs to be the fastest processor/memory all of the above the others can be looked at on a usage basis. Overall the best switches in my opinion are Cisco's because of the support you get with them. Never use hubs in my opinion and get something at the Core that can do layer 3 because you do not want just one big network. That away if a site goes down it does not take the whole network down. If you would like to email me any questions I would be glad to help wroming@ci.killeen.tx.us

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