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Deep Dive SmartLink Server Infrastructure

Wolfgang Member ✭✭
edited April 2020 in SmartSDR for Windows
Hi All - I would like to know more about the Flexradio SmartLink Server infrastructure. How does this server infrastructure looks like? Where are the server physically located? What type of servers?
I ask this questions because of the following. I operate my Flex 6500 remote on a Swiss moutain 1'660m with an Internet-Connection with 25 MBit/s Downlink and 4.5 MBit/s Uplink. Sometimes the signal indicator next to the SmartLink Text shows "red" or "yellow". I'm not sure, is this because of our Internet-Connection or the load of the SmartLink Server Infrastructure?
73 de HB9RYZ, Wolfgang www.hb9ryz.ch


  • Jon_KF2E
    Jon_KF2E Member ✭✭
    edited November 2019
    Hi Wolfgang,

    I can't answer your questions about the smart link infrastructure but I can tell you that here, with a gigabit up/down I still occasionally see yellow and red. It does the same with a lan connection between the radio and smartsdr. I think it's "normal"

  • Mark Erbaugh
    Mark Erbaugh Member ✭✭
    edited February 2020
    I believe the Smartlink servers only establish the initial connection to the Flex. Once the radio and client have connected, the communication is direct, IP address to IP address.

    I have seen red or yellow signal indications with the computer and Flex both hardwired to the same physical network switch.
  • Mike-VA3MW
    Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
    edited April 2020
    Hi Wolfgang

    In the SmartSDR manual, it describes how the colours changes based on packet loss.

    For HF operating, it is more than just upload and download speed. Latency is the key measurement tool you want to watch.

    When using SmartLink, it is a peer to peer connection when operating.  The Flex servers only initiate the connection but are not part of the communications path at all. 

    If you are seeing more lost packets, then you will need to investigate the routers at each end, are you using any WiFi at all (WiFi will be the worst offender), other streaming devices, etc.

    Even though streaming TV woks wonderfully, you can afford to drop a lot of data packets (and you do) when streaming TV, etc.  However, we never notice it since the human brain fills in the gaps.  It is different with HF radio and it can show every flaw in your data communications.

    When debugging packet loss, you need to look at every piece from the LAN connection at the radio to the LAN connection to the actual user.  Anyone of those can contribute to packet loss.

    Mike va3mw

  • Mark Earle
    Mark Earle Member ✭✭
    edited November 2019
    The infrastructure only gets your client connected to the radio. 
    On the left side, display,, there is frame rate, and display rate. Drop those way down, to say, 5. The waterfal will update less often, using less upload bandwidth. Where my Flex 6400 is, the internet is 1meg upload. Turning those two down, I use about 200-250k of the upload vs 750 or so with default settings. You must change them per band. 

    Using a VPN can also add delay/ latency. Sometimes, operating the client wired instea of WiFi improves things. 

    de Mark WA2MCT
  • Asher - K0AU
    Asher - K0AU Member ✭✭
    edited April 2020
    Managed to find a used Maestro and got it working pretty quickly from my remote site.


    Couple curiosities: My Maestro connects to the home site using SmartLink. Other connectivity between the sites is over a site-to-site VPN.


    The Maestro reports +/- 120ms round trip latency, while a VPN ping to the radio’s IP address reports +/- 50ms latency.  I don’t have any way to trace the SmartLink network path, but I’d be surprised if it’s radically different from the VPN tunnel path, so any clues on why latency reports are so different? Is SmartLink measuring latency through more of the network stack?


    Other curiosity is intermittent disconnects. I have no control over network path delays and congestion. My local path delays are on the order of milliseconds. There must be a spec on what triggers a disconnect – is it k of n dropped packets? Out of order reception?  And curious why SmartLink doesn’t seem to have a session layer to restore lost transport connections. Why does SmartLink require manual intervention to reconnect? (I’m running V2.6.1.)


    I can’t tell if the Maestro connection is more fragile than an SSDR SmartLink connection from my computer.


    I tend to leave radios running overnight with an FT8 decode feeding into PSKReporter, and it would be nice if it stayed up consistently.


    Overall: it’s remarkable it works as well as it does, but it seems rather fragile and I’m not sure I’d set up my main use case to be remote over SmartLink.

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