nanog mailing list archives

Re: OT - Small DNS "appliances" for remote offices.


From: Rob Seastrom <rs () seastrom com>
Date: Wed, 18 Feb 2015 20:23:37 -0500


"Robert Webb" <rwebb () ropeguru com> writes:

What I do not like about the Pi is the network port is on the USB
bus and thus limited to USB speeds. 

Pretty much all of the ARM boards have their ethernet ports on HSIC
channels (480mbit/sec, no-transceiver-phy USB for on-board use -
maximum length is 10cm).

The Pi-B shares the single HSIC channel with the USB hub for the
keyboard and mice.  It seems from looking at block diagrams and lsusb
output that the ODROID U3 has an SoC with multiple HSIC channels and
dedicate one to to the ethernet (though the "bus" vs "port"
distinction is suspect).

pi@raspi-b ~ $ lsusb -t
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc_otg/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=hub, Driver=hub/3p, 480M
        |__ Port 1: Dev 3, If 0, Class=vend., Driver=smsc95xx, 480M
pi@raspi-b ~ $ 

root@odroid:~# lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=exynos-ohci/3p, 12M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=s5p-ehci/3p, 480M
    |__ Port 2: Dev 2, If 0, Class=Vendor Specific Class, Driver=smsc95xx, 480M
    |__ Port 3: Dev 3, If 0, Class=Hub, Driver=hub/3p, 480M
root@odroid:~# 

But 480 is greater than 100, and none of the Pis have ethernet faster
than 10/100.  The long pole in the tent is definitely not the USB, and
single stream tcp throughput is fine.

pi@raspi-b ~ $ curl -o /dev/null http://172.30.250.101/bigfile
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  989M  100  989M    0     0  11.1M      0  0:01:28  0:01:28 --:--:-- 11.1M
pi@raspi-b ~ $ 


-r


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