Server access over Radio Links

Posted on 2014-08-27
Last Modified: 2015-01-13
I have two sites - Main and Shop2.
They have a radio link between them (throughput is between 100-140Mbps)
For ease I sent the radios as a bridge, so the LAN at Shop2 is an extension of the LAN at the Main location.
The PC at both locations have redirected folders - Desktop, My Documents, App Data to a share on the File Server at the Main location,
Also at the Main location is the ERP system which is an SQL based application.
The application is run from a mapped drive to the SQL server.

The radios started failing so both were replaced with the latest model and now things are not working as expected.

The ERP system operates so slow it is un-usable.
From Shop 2, If I ping the server I loose a lot of packets (4 out of 25).  If I ping the LAN interface on the router I loose 1 out of 50 packets and if I ping the radio at the Main shop, I don't loose any packets.

This is were things get confusing.  Pinging the Radio and not loosing any packets would indicate the radio link is good, which is also what the radio monitoring/management software indicates.

So why would I get a greater packet loss when pining the server over the router.

Just to make it even more confusing.
At the Main site - If I ping the servers - there is no packet loss.
If I ping the radio at the main site, there is packet loss around 4 per 25 packets.

All this could point to a cable problem between the main site radio and the switch.  However if this is the case, why when I ping from Shop 2, to the router is minimal packet loss.

Again this all started to happen with the replacement of the radios.

So if the radios are causing the problem, but the link is good, what good it be?

My only possibility would be the delay across the radios has increased, but would a small increase in the delay cause this type of issue?

IF this is the case are there any settings on the servers/PC's that I could change to compensate for the increased delay?

Any ideas on how to fix this would be helpful.

Thank you
Question by:bmcollis
    LVL 82

    Expert Comment

    by:Dave Baldwin
    Sounds like interference from other sources to me.  If you're on the WiFi bands, you're still subject to interference from other wireless routers.  What kind of antennas are you using?

    Author Comment

    They are 5Ghz Radios.  One of the features of the software is to look at the frequency's in use, allowing you to then select a band that is not in use.  
    If it was interference from another radio source, then I would expect drop ping packets when ping from shop 2 over the radio link to the radio at the main shop, yet I don't get any.

    I am going to get a cable tester and check the cable at the main site from the switch to the radio - don't suspect there will be anything wrong with it.

    Will also see if I can change the speed on the interface of the radio at the main site from 1G down to 100M.

    LVL 82

    Expert Comment

    by:Dave Baldwin
    5GHz is somewhat more sensitive than 2.4GHz to inline interference like trees I believe.  Is the line-of-sight between the antennas completely unobstructed?

    Accepted Solution

    Hi Dave,

    Would not say completely unobstructed!!
    i.e. when on the roof of the buildings, I can not see the areal on the remote building.  Having said, that I am also not 10' above the building roof like the antenna.
    The distance between the radios is 1500' (550m) and the only thing between them is a flat roof building, that is not that much higher than the two buildings the radios are on.

    Again, the old radios worked the new don't, yet it appears the link between them is solid, the management software is indicating 140Mbps between the radios.

    I think the issue is between the Radio at the main building and the switch.

    I have moved from bridging the two sites to having Shop2 on its own network, connected by the radios.  This means the radio is now plugged into the firewall and I have a rock solid link and all is working OK.

    Based on that, I don't think I will worry about trying to figure this out much more.  Its working.  If it was a different switch, it might have very well worked, but I don't have a different switch to try.

    Thank you for your input.


    Expert Comment

    by:shuhail ak
    first of all connect only p2p device and check the connectivity , ping with 65000
    from both location .if it fine , try to ping through router .if you find issues check the setting for duplex and on router .i guess might me speed mismatching

    Author Comment

    Hi Dave and Shuhail,
    I know this is now way old, and I appreciate your input.
    As I indicated in my last post moving the link to the router seemed to fix the issue, so I left it at that, which is way I have not been back to respond.
    Shuhail, I did not get a change to follow your suggestion, but if/when I have a bit of time to burn will try it.
    At this point I am going to mark moving the connection to the router as the accepted solution as it did fix the issue.

    Author Closing Comment

    Moving the radio link fro the switch to the router fixed the issue.

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