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JParedesC_24093's avatar
JParedesC_24093
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Nov 16, 2016

Load Balancing DNS queries with Geolocalization from Cell Phones via APNs

Hello:

 

We are trying to implement BIG-IP DNS (GTM) on an ISP Customer, and they are now serving the DNS service for the Mobile Phones via APNs, we would like to use geolocalization to load balancing the Phones' DNS queries according to their location but we know that the APNs translates the Source IP (Phone IP) to just one IP address, so when we will implement the Geolocalization LB in GTM, the BIG-IP can't read the Source IP, because the APNs makes an IP translation. Does it exist any mechanism to get this source IP from APN and how we can identify it?

 

Regards.

 

Joel

 

application delivery
BIG-IP DNS
iRules

4 Replies

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  • David__Pasch_24's avatar
    David__Pasch_24
    Icon for Nimbostratus rankNimbostratus
    Nov 16, 2016

    Joel, I am no cellular guy, but I have a question for you. If the cell phone is using the APN as proxy, making it the LDNS, wouldn't you want to geolocate based on APN IP address? Does all of a cell phones data go through the APN anyways?

     

    Clueless and curious.

     

    thanks!

     

    D

     

  • JParedesC_24093's avatar
    JParedesC_24093
    Icon for Nimbostratus rankNimbostratus
    Nov 16, 2016

    Hi David:

     

    Thanks for your comments, we want load balancing based on Phones' IP address. You're right, the phones data go through the APN now.

     

    Best Regards!

     

  • Leonardo_Souza's avatar
    Leonardo_Souza
    Icon for Cirrocumulus rankCirrocumulus
    Nov 17, 2016

    The GTM will do topology load balancing (geolocation) based in the source ip it receives. Unless there are some crazy requirements, the users connected from one APN are all located in the same area, so the load balance decision should be the same to all users in that area.

     

    If this was HTTP proxy, you could add the source IP in the HTTP headers, but as this is DNS and most likely UDP, not easy to do.

     

    Have a look in this questions/answers because is more or less the same you are asking:

     

    https://devcentral.f5.com/questions/mac-address-field-50132

     

    https://devcentral.f5.com/questions/udp-protocol-insert-client-source-ip-49607

     

  • David__Pasch_24's avatar
    David__Pasch_24
    Icon for Nimbostratus rankNimbostratus
    Nov 17, 2016

    I don't think you are going to be able to do this within the DNS protocol, as there is no X-FWDR type functionality.

     

    But, I am still not sure why you would want to do this. Once again, I am not a cellular guy, so not sure how these APNs fully work. I am just applying what I know about Enterprise Internet Proxies. If they have DHCP style IP ranges they assign to phones they proxy, and use IP that is geolocated, it would seem using the phone's IP would only make it less accurate.

     

    Do APNs have to assign IP ranges that are geographically accurate? OR do they only have to be at the public side of the APN?