[Hidden-tech] Network question

matt lampiasi mattl at florenceit.net
Thu Dec 1 00:48:51 EST 2011


I should have said overall network losses, never near 93% in most office networks.  I'm sure your numbers for the specs themselves sound right but that is not to be expected end resultant bandwidth on a network with sometimes multiple protocols and certainly connected to multiple devices while downloading said file on a most likely imperfectly designed network that is being shared by other uses locally. not even sort of close to that for end user bandwidth left over. 

Thanks,
Matt Lampiasi

On Nov 30, 2011, at 22:14, "Matthew S. Crocker" <matthew at corp.crocker.com> wrote:

> 
> Ethernet has a very low overhead.   Ethernet is 97% efficient at 1500 byte MTU.  There is a reason why Ethernet is the protocol of choice for carriers these days.  Cheap and FAST.
> 
> TCP over Ethernet is 93% efficient which is what you get when you download files.
> 
> Hubs are bad, throw them out and get switches.     
> 
> 
> From: "Matt Lampiasi" <mattl at florenceit.net>
> To: hidden-discuss at lists.hidden-tech.net
> Sent: Wednesday, November 30, 2011 1:44:08 PM
> Subject: Re: [Hidden-tech] Network question
> 
>    ** Be sure to fill out the survey/skills inventory in the member's area.
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> 
> 
> 
> Hi
> 
> Lot's of possibilities: Roberts comments make sense as a possibility. Also keep in mind that ethernet has quite a bit of protocol overhead so that if you had 10mbps cabling and/or cards you might see 30% drop. 
> 
> You don't say what kind of equipment this is all running through. If you have a 10mbps hub or 10mbps network cards in the pc's obviously that would be a problem. 
> 
> You're saying the front part of the building gets ok speeds? 
> 
> so if the networks hub or switch this connection routes through in the back is slow old or inefficient it can definitely slow things down.  you say it goes into a patch panel. it must go into a switch or hub in the back. what kind? 
> 
> cable ratings can make a big difference over a longer drop like that. the longer the wire and the thinner the strands the more the signal loss (drop in speed). 
> 
> I'm totally not up on that but any cabling guy will be able to tell you what to use.  If your pc's have gigabit or at least 100mbps network cards then the bottleneck is the cable run from the front , or the switch/hub it goes into in back. (assuming the run goes into the same switch out front that all the other pc's use. ?)
> 
> cat6 will give you less signal loss, but you have to make sure ALL of your distribution equipment (patch panels, ends crimped on the cables, etc .) must be rated for the same as your higher end cable, and i would make sure its shielded.
>  
> 
> Best, 
> 
> Matt Lampiasi               
> 
> On Nov 29, 2011, at 6:50 PM, hidden-discuss-request at lists.hidden-tech.net wrote:
> m>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> Have a perplexing situation. We have 20 megabit down internet service from
> Comcast coming in to the front building of our place, gets passed via Cat 5
> probably 150 feet to a patch panel, which distributes it to ethernet ports
> in 5 or 6 rooms in the back building.
> 
> Why would the connections in the rear building only provide 6-7 megabits?
> Could we replace switches or panels in the rear building to provide more
> bandwidth to the individual connections? Or is the splitting of the signal
> in the rear building the issue?
> 
> 
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