[USRP-users] Multiple N210 - Hardware Setup

Jan Metzger jan.metzger at gmx.de
Thu Mar 3 10:09:29 EST 2016

I have been using USRPs (N210) for some years. My typical setup was a normal consumer PC (Dell PC) with Ubuntu Linux and a cheap consumer NIC from Realtek. With this setup and some tweaking of the Linux configuration [1] [2] it was possible to create a really long-term stable RF signal source/sink as long as the sample rate was not too high, that means < 12.5 MSample/s. With sample rates above 12.5 MSample/s there were always some overflows/underflows reported by the UHD after some time (some days). I never found the bottle neck that hindered the system to work stable at higher sample rates. However, I was always wondering if the problem is somehow related to Realtek NIC.
For a new project I need to create a setup that can handle up to 12 USRPs (N210). Because of my experience with the setup described above I think it is necessary to invest some more thoughts to find a suitable hardware setup to realize this system.
Use case:
The systems must play back up to 12 pre-calculated IQ files via the 12 USRPs. There is not live signal processing, this is done during the creation of the IQ files. Therefore the system “only” needs to provide the IQ data via Ethernet to all of the USRPs. The typical sample rate per device for during the play back will be 10 MS/s – 12 USRPs x 10MS/s. But sometimes some USRPs (let’s say 6) will be idle and the remaining 6 USRPs will play back IQ files with a sample rate of 20MS/s – 6 USRPs x 20 MS/s.
Are there any recommendations or even USRP related performance tests for motherboards and 1 GbE NICs to build a system as described above?
I’m aware of these pages [2] [3]. Is there any comparable information regarding 1GbE NICs?
Hardware setup idea:
I searched the web to find suitable hardware and put together the following hardware components. Please comment on this setup idea.

Motherboard: 1 x ASUS Z170-WS (4 x PCIe 3.0/2.0 x16 (8x/8x/8x/8x mode))
NIC: 3 x Intel I350-T4 V2 retail (PCIe 2.0 x4, 4x 1000Base-T)
CPU: 1 x Core i7-6700
RAM: 16 GB
Storage: several Samsung SSD 850 Pro 512GB 2,5" / SATA


[1] http://files.ettus.com/manual/page_transport.html[https://deref-gmx.net/mail/client/dereferrer/?redirectUrl=http%3A%2F%2Ffiles.ettus.com%2Fmanual%2Fpage_transport.html]
[2] http://files.ettus.com/manual/page_usrp_x3x0_config.html[https://deref-gmx.net/mail/client/dereferrer/?redirectUrl=http%3A%2F%2Ffiles.ettus.com%2Fmanual%2Fpage_usrp_x3x0_config.html]
[3] https://www.ettus.com/kb/detail/usrp-b200-and-b210-usb-30-streaming-rate-benchmarks[https://deref-gmx.net/mail/client/dereferrer/?redirectUrl=https%3A%2F%2Fwww.ettus.com%2Fkb%2Fdetail%2Fusrp-b200-and-b210-usb-30-streaming-rate-benchmarks]

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