OT - Small DNS "appliances" for remote offices.

Thu Feb 19 13:26:36 UTC 2015

On 2015-02-19 15:13, Rob Seastrom wrote:
> Denys Fedoryshchenko <denys at visp.net.lb> writes:
> 
>> Beaglebone has gigabit mac, but due some errata it is not used in
>> gigabit mode, it is 100M (which is maybe enough for small office). But
>> it is "hardware" mac.
> 
> The Beaglebone Black rev C BOM calls out the ethernet phy chip as
> LAN8710A-EZC-TR which is 10/100 so there's your constraint.  The MAC
> is built into the SoC and according to the datasheet the AM3358B is
> 10/100/1000.
> 
>> Another hardware MAC on inexpensive board it is Odroid-C1.
> 
> Difficulty: hardware MAC tells you nothing about how it's connected,
> either on the board or internally in the SoC.  Ethernet on Multibus
> and Ethernet on PCIe (neither likely on an embedded ARM ;-) are both
> "hardware MAC" yet the bus-constrained bandwidths will differ by
> several orders of magnitude.
> 
> -r
Well, i guess for DNS it wont matter much(400Mbit or full capacity). But 
stability of driverand archievable pps rate on it,
due poor code - can be a question. And mostly this products are "Network 
enabled", but networking are very "lightly"
used, not as it is used on appliances, 24/7 traffic, sometimes 
malicious.
About Beaglebone, probably reason is this errata:
"While the AM335x GP EVM has a Gb Ethernet PHY, AR8031A, on the base 
board,
the PCB was designed to use internal clock delay mode of the RGMII 
interface and
the AM335x does not support the internal clock delay mode. Therefore, if 
operating
the Ethernet in Gb mode, there may be problems with the 
performance/function due
to this. The AR8031A PHY supports internal delay mode. This can be 
enabled by
software to guarantee Gb operation. However, this cannot be done to 
enable
internal delay mode for Ethernet booting of course. "
Or maybe they just put 100Mbit PHY to make BOM cost less.

As far as i know, Raspberry PI ethernet over USB might be fine for DNS 
too, but before it had issues with
large data transfers (ethernet driver hangs). No idea about now.

---
Best regards,
Denys