[USRP-users] Gigabit Ethernet Switch

Stan Gamla cystrin at hotmail.com
Sat Nov 17 19:11:54 EST 2012


Shep and Josh,
 
Thanks for identifying the GS108 (8-port GigE switch). 
http://www.netgear.com/business/products/switches/unmanaged-switches/unmanag
ed-desktop-switches/GS108.aspx#two
 
As I only need to run two USRPs, I would presume that the (equivalent) four
port GS105 is also adequate:
http://www.netgear.com/business/products/switches/unmanaged-switches/unmanag
ed-desktop-switches/GS105.aspx#two
 
Please let me know if there is a difference (I cannot see one in the
specifications).
 
The Netgear switch that I have tried (and had "issues" with) was a GS605.
Its specification is similar to the GS108 (and GS105) with a couple of
exceptions: 
 
Latency           GS108            GS605
10 Mbps:     30μs (max)     1250 μs (max)
100 Mbps:     6μs (max)       125 μs (max)
1000 Mbps:   4μs (max)         15 μs (max)
 
GS108
IEEE 802.3i 10BASE-T Ethernet
IEEE 802.3u 100BASE-TX Fast Ethernet
IEEE 802.3ab 1000BASE-T Gigabit Ethernet
Honors IEEE 802.1p and DSCP priority tags
Jumbo frame: up to 9,720 bytes
 
GS605
IEEE 802.3i 10BASE-T Ethernet
IEEE 802.3u 100BASE-TX Fast Ethernet
IEEE 802.3ab 1000BASE-T Gigabit Ethernet
IEEE 802.1p priority tags
IEEE 802.3x Full-duplex flow control
Jumbo frame support (9,000 byte frames)
 
Should these differences make a difference?
 
The GS108 is categorized on Netgear's website under "office" while the GS605
is found in "home".
 
 
 
Marcus,
 
Regarding the INTEL Gigabit Ethernet device, I used the GS605 together with
an Intel 82577LM NIC.
 
Thanks,
 
Stan
 
 

  _____  

From: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of
Shepard Siegel
Sent: 17 November 2012 22:38
To: josh at ettus.com
Cc: usrp-users at lists.ettus.com
Subject: Re: [USRP-users] Gigabit Ethernet Switch


We will second Josh's blessing of the GS108.
They just work. We've been using then to aggregate 1-4 N210s for most of
this year w/o any issue.
http://sls.smugmug.com/Professional/Platform-Blue/i-VxZf5P5/0/XL/D7K_1660_Dx
O-XL.jpg
-Shep




On Sat, Nov 17, 2012 at 2:44 PM, Josh Blum <josh at ettus.com> wrote:




On 11/17/2012 11:37 AM, Stan Gamla wrote:
> Marcus,
>
> Thanks for the insight.
>
> Do you know of any GigE switches that *will* work (properly)?
>

These little blue netgear switches work wonderfully for everything I
have ever used them for:
https://upload.wikimedia.org/wikipedia/commons/b/ba/Netgear_ProSafe_8_Port_G
igabit_Switch_GS108_front.jpeg

:-)

-josh

> Stan
>
>   _____
>
> From: Marcus D. Leech [mailto:mleech at ripnet.com]
> Sent: 17 November 2012 01:11
> To: Stan Gamla
> Cc: 'Ian Buckley'; usrp-users at lists.ettus.com
> Subject: Re: [USRP-users] Gigabit Ethernet Switch
>
>
> On 16/11/12 06:19 PM, Stan Gamla wrote:
>
> Ian,
>
> The GigE switch (not a router) in question was bought a couple of months
ago
> and should be rid of the legacy issues that you may have been referring
to.
>
> Just to give a little background, there are two N210 USRP/SBXs--one used
for
> transmission only, the other for reception only. Two units are needed in
> order to provide a system with a level of RF Tx-Rx isolation that is much
> greater than that offered by a single N210 USRP/SBX (~40 dB). Each N210
USRP
> has a unique IP address (192.168.10.2 and 192.168.10.3) and both units are
> connected to the same GigE NIC via a dedicated GigE switch (used to carry
> the traffic between the USRPs and the PC only).
>
> The first USRP/SBX is used as a transmitter and its interpolation factor
is
> set to 512. The second USRP/SBX is used as a receiver and its decimation
> factor is set to 512. Using the simple equation presented in this forum by
> Erik Luther and remodelled by Marc Epard, the data rate created on the
GigE
> bus for one USRP would equate to (100e6 / 512) * 16 * 2 = 6.25e6 bits/s.
> Together, the two units would double this figure to 12.5e6 bits/s which is
> considerably less than the 1000e6 bits/s offered by GigE.
>
> Based on the comments posted by Marcus D. Leech, more questions come to
> mind. For example:
>
> *
>
>       Do some GigE switches do "things" that other GigE switches don't?
> *
>
>       Does the NIC have to be configured in a special way?
> *
>
>       Does the setting of the MTU play an important role?
>
> Thanks,
>
> Stan
>
>
> Some 1GiGe switches have *much*  better (higher-performance) switching
> fabric than others.  Many of
>  the consumer-grade 1GiGe switches are basically 1GiGe switches in name
> only--the switching fabric is,
>  to put it mildly, *crap*.
>
> You may also be encountering problems with your NIC.  The Intel 82579LM
is
> known to have *fatal* packet-loss
>   bugs in the hardware design that cause even modest-level continuous
flows
> to cause it to drop frames when
>   it doesn't need to.  This is a problem independent of Gnu Radio or USRP,
> but these SDR traffic flows seem
>   to reveal this issue.
>
>
>
>
>
>
>
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>

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