On 11/13/2015 01:44 PM, Paul Smith wrote:
On Fri, Nov 13, 2015 at 6:06 PM, Rick Stevens <ricks@xxxxxxxxxxxxxx> wrote:
Is there something in Fedora that I might use to determine the
maximum
speed the network card of my computer can attain on Internet? I am
thinking about wired Internet and not about wireless Internet.
Thanks in advance,
You might need to explain the reason for your request since, it may
change the answer.
As an example, my computer has a GigE port that runs to a 100Mbit
simple switch before getting to anything else. So I would be limited
to a theoretical maximum of 100Mbit but I might want to know how fast I
can transfer files to/from another computer in my LAN. The bottleneck
here could be the switch, my NIC, the other computers NIC, OS limits,
firewall slowdowns etc.
So, for me I would really want to test an actual file transfer using a
number of setups. Depending on each computer I could try Samba, FTP,
SCP. I might run a wire to bypass the switch. I might try with
firewalls and antivirus disabled.
All this will also give me some clue on how fast I could run if I was
able to get a fiber connection, to let me know if my system would be a
serious limit to getting the full 1G of true fiber. Obviously the
switch would have to be upgraded in my case.
Generally speaking, any given NIC that has proper firmware and is in
a relatively modern computer will run very close to the rated wire
speed--provided the other end of the cable can handle it as well. Note
that the effective transfer rate will usually be about 80-95% of that
(for a 1Gbps NIC, 800-950Mbps).
This does not include any overhead involved in the protocol used. You
will find that things like FTP, rsync and the like will show lower
data transmission rates (e.g. multiplying the number of bytes
transferred by 8 to get number of bits transferred) due to their
overhead and that they're dealing with TCP's inherent nagle algorithm
and handshaking. TCP is designed to make sure things get to where
they're supposed to go, and with that comes a lot of overhead. Things
like UDR (rsync-over-UDP) will show much closer to the theoretical data
transmission rate due to its use of UDP.
The most common bottleneck to raw speed is the wire, switch, router,
gateway or ISP that the NIC is connected to. You'll rarely find the NIC
itself the limiting factor.
Thanks to all respondents! I could now determine that my network card
is a 100Mbps Fast Ethernet, and now it is clear why the speed test
(http://www.speedtest.net/) shows a download speed of just 85 Mbps
when my contracted speed is 120 Mbps.
85Mbps sounds about right for a 100baseT NIC on one of those tests
(they typically use TCP). You can always verify your type of NIC using
ethtool.
My laptop has a 100baseT port. When I need gigabit, I use a USB3 gigabit
dongle. Note that you need USB3 for this--USB1.1 and USB2 aren't fast
enough.
----------------------------------------------------------------------
- Rick Stevens, Systems Engineer, AllDigital ricks@xxxxxxxxxxxxxx -
- AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 -
- -
- If at first you don't succeed, quit. No sense being a damned fool! -
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