[olug] Full Duplex - NIC

[Will Langford]

Even something like:

Router -> switch => all other switches and boxes ... and have it so the
router has only a single WAN and a single LAN connection... might help some.
 This way the router doesn't have to possibly inspect every packet it sees
to see what to do it with (i'm unsure if routers have a regular hub/switch
logic that then passes unknown addy's to a router chip or not, or if the
router chip handles even acting like a chip).  but giving the router a lot
less to think about is usually a good idea when it's just an at home cheapie
inet router.

if you vlan any -- a 4-12 byte smaller MTU might be good as well.. since
that'd eat a few extra bytes in the ethernet frame, causing possible
fragmentation.  there's also a case where some NIC's or switches prefer a
smaller MTU as well.  Ya don't have to do anything drastic like 596, but
1400-1490 really really might help.  Using ICMP to ping with varying packet
sizes across the network might show an MTU fragmentation size limit.

-Will


On Thu, Feb 4, 2010 at 12:59 AM, Kelly Williams
<kellywilliams81 at gmail.com>wrote:

> Will Langford wrote:
>
>> On Wed, Feb 3, 2010 at 11:56 PM, Luke-Jr <luke at dashjr.org> wrote:
>>
>>
>>
>>> On Wednesday 03 February 2010 08:24:09 pm Kelly Williams wrote:
>>>
>>>
>>>> I checked my Nic on my server and it run full duplex. I noticed that I
>>>> was running two machines with XDMCP disable it on both machines and
>>>> still not getting any faster. I took off a switch on my network still
>>>> not any faster. Any thoughts.
>>>>
>>>>
>>> One thing to consider is that if you're using TCP, there are ACK packets
>>> going
>>> the other way. Usually it shouldn't make a big difference, but if you're
>>> sending lots of small packets, it could...
>>>
>>>
>>>
>>>
>> Lots of tiny packets would be inherently slower, yup.
>>
>> Lowering your MTU to 1490 or similar can help some, especially if you're
>> VLAN'ing.  As Luke suggested, google is your friendly.
>>
>> Conversely, if all of your network can handle it (or segmented bits can),
>> jumbo frames (huge MTU over 1500) can also possibly benefit you a lot.
>>
>> Out of curiosity, what about your network is slower ? Certain things are
>> 'inherently' slower.  SFTP stuff is typically 2-3MB/sec, Windows file
>> sharing will also automatically chop your transfer speed in half over
>> whatever medium you're using (ie: on a 115200 serial connection, you'll
>> only
>> get 5k/sec versus expected 11k/sec... or 512K/sec over 10baseT, etc).
>>
>> The iPerf/jPerf/etc tools mentioned by Rob is also a great idea.  Wire
>> sniffers might be a last ditch effort to see what's going on, too.
>>
>> The only hardware related thing that comes to mind is that cheap NIC's can
>> be flakey, but even worse is cheap hub/switches.  For example: an Encore
>> branded switch is begging for performance and stability issues (we've
>> noted
>> it in the field).  Even some Netgear switches have issues...
>>
>> -Will
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>>
>>
> My router is netgear and the switch that is connected to the server is a
> smartstack. The server was a old emachine desktop runs sweet with linux
> sucks with windoz. It does make sence when transferring lots of small files
> it gets slower but when transferring ISOs over the network to the server it
> works nice. I created a digram of my network.
> http://www.flickr.com/photos/24514670@N04/4329806806/ the switch that is
> connected to the servers is smartstack switch and then the switch that is
> connected is a 5 port netgear switch and just a basic 45.00 netgear router.
> I was thinking that I should take out the netgear switch and run every thing
> on the smartstack. then have the router has just the gateway, just one cat5
> to the smartstack switch. I believe that would get rid of bottle necks in my
> network. any advice. Thanks for the help.
>
> Kelly,
>
>
>
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