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Best network Topology ?

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Last Modified: 2013-12-23
Hello Gurus,
This is my situation :
I have a building that has 4 floors on each floor a number of pc varying from 5 to 15 PCs
I need to install a networking cables , the best possible (quality/Price of course).
That was my suggestion to the customer....
On each floor we install a switch 1Gb and the cabling be 1Gb and from each floor I get 1 connection
going to the server room (5th floor) .
but he has asked me a question that I could not much answer..
Would there be any bottleneck Vs the topology to send all the PCs connections to the server room ?
(around 60PCs)
Now I have read somewhere that even if your connection is 100Mb (or 1Gb) windows doesnt NEVER use that speed...
it uses a max. of 1 to 2 mb/s so 100 Mb or 1Gb will never be a bottleneck due to the network...
now on the NIC of the server that's another issue..
My question and concern is :
what is the difference in speed between sending 60 cables to the server room (on a switch)
and sending 4 cables to the server room (on a switch ) but those 4 cables would be sent from 4 switches ?
So I am looking for your professional help here.

thanks a lot


Pierre

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Lee W, MVPTechnology and Business Process Advisor
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Commented:
First, workstations/windows uses FAR MORE than 1-2 Mbit - this is easy to prove and test... do the math...

Provided your drops would not be longer than 100 meters, then it's as they say, 6 of one and half a dozen of the other.  That is, really not much of a difference.  With a switch on each floor, you end up potentially having more points of failure... so I guess, with only 60 drops, I'd probably say, if you can afford it and the drops are less than 100 meter TOTAL cable length, then I'd run them all to one location.  Otherwise, use a minimum of switches to chain them together.

A cable length of 20 meters is not going to be any better than a cable length of 60 meters, assuming there's no difference in cable quality.
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tigermattSite Reliability Engineer
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Commented:
normally in a 100Mb connection , how much windows uses as a max ? we all know that it nevers uses the whole thing ..right ????
If I have 10 users connecting to a server via 1 switch (normal and usual setup) in that case R U saying me that it is a wrong setup and that there will be network congestion ????
I really need help to understand this !!!
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Commented:
leew.
due to the building architecture having the 60 cables going up to the server room is a real challenge.
that's the issue !!
hence my argument with the customer !!
I am quite positive that it wont matter as speed factor whether you go with 60 cables to the server room or
you fragment it through switches for every floor... in all cases the NIC card of the server will be the bottleneck !!!!
that;s what I think... (not sure if that's right...) hence my question here seeking for prof. advice and documentation so I can
convince my customer which direction would be best !!
thanks again !
Lee W, MVPTechnology and Business Process Advisor
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Commented:
Not sure what to tell you - present your customer with the cost of both - let them pick.  You can only advise them.  If they choose to go against your advice, it's not your fault.
Aaron StreetTechnical Infrastructure Architecture and Global Network Manager
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tigermattSite Reliability Engineer
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Commented:
> the NIC card of the server will be the bottleneck

As I have already mentioned numerous times, you can get around this issue by using 2 or more NIC cards in the server, configured in a NIC Team. If all the cards are gigabit and they go back to gigabit ports on the switch, this could potentially allow you to have 2Gbps or higher connectivity out of the server.

Depending on the load and use of the server would affect whether you actually need this setup, or if it is just simple word documents and email as has already been mentioned, you could probably get away with a single gigabit NIC in the server.

-tigermatt
Aaron StreetTechnical Infrastructure Architecture and Global Network Manager

Commented:
A bottle neck is only a bottle neck if it restricts traffic.

if your server is only having to server up 10Mbs of traffic. the NIC will not be a bottle neck..

if you have 10 X 1gig links connected to a between 2 switchs with a 100Mbs link on to another 10 X 1gig links. You can only term the 100Mbs link a bottle neck if it is actuly causing a slow down in traffic. If your network is not using the link to compacity then dont worry about its speed

And the actuly bottle neck is more lickly to be the links between switchs rather then the switch to server. A 1gig link will transphere over a DVD's worth of data in about 30 seconds. There are very few applications with 60 users that come any where close to this kind of data transfer. so in 99% of cases Duel NIC cards are required for redundency rather than data through put.

The fact is with 500 people accessing 30 odd servers with a single core 1gig link inbetween. It rarely goes above 5% throughput!!!!

Author

Commented:
Thanks guys for your help ,but Iam sorry to see that I did not see any "scientific opinion "..meaning based on real numbers ...
I mean here is the issue...
I have 1 server 1 NIC 100Mb ...60Pcs connected to that Server. 100Mb NIC in all.
applications ? ORacle database of around 30GB. + home folders for all the users... Office use (Word& Excel mainly...)
There must be a study somehow ..somewhere to tell which  is the most efficient network topology...
linking all the 60pcs to 1 main switch and the server ....
or
having 4 switches , 1 on each floor and having the 4 switches getting in the main switch and the server NIC...
How much windows uses of the 100MB ?
I mean , if I try to copy a big file over the network let's say 100Mb...will it take 1s ? I am sure not...
If U haven't tried ...try and see.... 1Gb file instead of taking 10s ...would take up to 3 minutes... and thats'having the network freee...
(meaning no network activity elsewhere !!)
So the real question remains...
HOW MUCH WINDOWS USES OF THE 100MB LINK ????????????????????????
thanks again guys !
Lee W, MVPTechnology and Business Process Advisor
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Most Valuable Expert 2013

Commented:
> So the real question remains...
> HOW MUCH WINDOWS USES OF THE 100MB LINK ????????????????????????
> thanks again guys !

The problem is there are too many variables.  Drivers impact performance.  Specific brands and models of network cards impact performance.  Fragmentation on the source and destination drives impact performance.  Network switches used impact performance.  Cable quality impacts performance.  Packet size impacts performance.  Concurrent users impact performance.  And there are other factors I'm sure I'm forgetting off hand.  Network professionals know all this.  

I've seen performance as high as 98% of a 100Mbit link... and I've seen far worse.  It all depends on these variables... HOW CAN YOU POSSIBLY EXPECT US TO KNOW ALL YOUR VARIABLES when it's virtually impossible to know them for our own networks?

This is just like gas milage - you CANNOT get a SPECIFIC, HARD value - there are too many variables - tire inflation, how "hard" you drive, how fast you drive, etc., etc.
tigermattSite Reliability Engineer
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Commented:
I completely agree with the points leew has already made. It is virtually impossible to answer that question.

Just to add to the author's original posts, I would certainly be looking at putting a gigabit network card in the server, or upgrading the port on its switch so it can get gigabit connectivity. Even though the workstations aren't actually doing much to drain performance from the server's NIC, a gigabit card would still be a good idea. It would aid the congestion problem greatly at the server end.

-tigermatt
Aaron StreetTechnical Infrastructure Architecture and Global Network Manager
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Author

Commented:
Thanks guys for all the information U shared with me.
I really dont know to whom I shall attribute the points...
U were all helpful !
Lee W, MVPTechnology and Business Process Advisor
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Most Valuable Expert 2013

Commented:
Split the points to each post that was helpful.

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