Flex 6500 wont get IP adress first time from cold

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  • Updated 2 years ago

To connect to the LAN/WAN I have a brand-new 5 port Ethernet switch under my desk which connects to a brand-new TP-link WIFI extender (the router is in another room).

This all works fine except when first powering up the Flex.

The desktop PC, a laptop and the OM2000a+ (which are also plugged in to the same ether switch) do get an IP address from the router first time.

However, the Flex 6500 (v2) does not. It always needs another power-cycle. As there are no diagnostics on the OLED display I have no way to know what is going on, just tat the v2 radio discovery does not find the radio.

The switch and the WIFI extender are left on 24/7 so an initialization problem is unlikely. In any case the PC, laptop and OM2000 do not demonstrate this symptom.

The work-around is to have to power cycle the Flex twice (without changing anything else) and hey presto the Flex now gets an IP.

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G8ZPX

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Posted 2 years ago

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Ken - NM9P, Elmer

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Do you have a Reserved IP Address for your Flex Rig established in your router? If not, try that and see if it speeds things up.
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Jim Gilliam

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I had the same problem and Ken suggested that I do the above and port forward on the router and that cured my problem.
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Mark - WS7M

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Alternatively, you could give it a static IP.  
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W9ILY

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I set up a static IP and that fixed the issue. However, if you do this and you change your network be SURE to change the static IP to DHCP first.
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Tim - W4TME, Customer Experience Manager

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We have seen this exact behavior with networks that use Wifi extenders.  

The last time I debugged this problem using Wireshark, what I saw was the radio is sending the DHCP DISCOVER packets (three of them) as soon as the radio is powered up and the Ethernet interface fully initializes, but the DHCP server (router) never sends the DHCP OFFER packet, so negotiation fails.  

What is surmised is that wifi extender (bridge) is a little slow in passing the broadcast packet because the radio is not yet in the MAC address forwarding table or either bridge (the switch and the wifi extender) and establishing the connection to the other wifi endpoint which is required before the DHCP DISCOVER packets can pass. Wifi is slow compared to a wired network.

I suspect that if you were to take the wifi extender out of the network path and use a wired connection, that this behavior would stop happening.

To answer your question about why your PC works, I'd have to Wireshark a Windows box booting up and look at the packet timings to know for certain.

A reserved IP address via DHCP will have the same timing issues.  A static private IP entered for the radio will not.
(Edited)
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Ken - NM9P, Elmer

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Thanks for the info, Tim.  It seems that I learn something every day.... or perhaps at my age, it seems that I RE-learn something every day!

To make sure I get my wording correct if I run into others with this situation...

They need to set the rig to a static IP that is outside the range that will be assigned by the router's DHCP, so the router will not try to assign the rig's static IP address to another device on the network?  (and they may need to narrow the DHCP assignment range in the router to leave some space for static IP's on the network, like Flex Rigs, printers, etc, that they may wish to use with a static IP.)

This seems to be one of the few situations where a Static IP is preferable....but don't forget what it is!  ha.  (I did that once on a NAS Drive, and it was a mess!)

Ken - NM9P
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Tim - W4TME, Customer Experience Manager

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They need to set the rig to a static IP that is outside the range that will be assigned by the router's DHCP, so the router will not try to assign the rig's static IP address to another device on the network?

It depends.  Some DHCP servers will only allow you to create DHCP reservations (assign a specific IP address to a device based on its MAC address) for unused IP addresses within the defined DHCP scope.  Other servers make you use an IP address that is in the IP subnet but not within the IP address range of the defined DHCP scope.

Static IPs are OK, you just have to manage them manually.  I use DHCP reservations for hosts that I want to have the same IP address allocated every time (my radios, managed Ethernet switches, and APs) and allow everything else to be dynamically allocated.  The only thing on my network where an IP address is assigned statically is the LAN IP address of my firewall/router.
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Ken - NM9P, Elmer

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OK, thanks. 

For the past several months, I have been switching most of my stuff over to Reserved IP assignments just to keep things more organized and consistent...Laptops in one range, Phones & tablets in another, Dish Network hopper & Joey's in still a different group, Smart TV's, DVD's & Roku boxes in another, my son's friends devices in another group, etc.

Call me OCD, but it makes it a lot easier to track down which device has gone rogue, and which ones I need to restrict from the internet when my 10 year-old needs to be sent to the "penalty box!"

I don't think I have anything on an unassigned/unreserved IP at the moment, since I was finally able to update my printer so that it doesn't need a static IP any more.

Reserved IP is so much more flexible and elegant . . . as long as the router lets you do it.  I once had a modem/router that would only let me reserve 10 addresses, and I had to do it via telnet.  (yuck)  I "inherited" it when I moved to a new parsonage in another town 9 years ago.  It didn't last long before it got replaced.

Internet tech has come a long way in a very short time.....

I started computing in the days of 100 and 300 baud dial-up modems and fidonet.  (At least I didn't have a "receiver cradle" ala the movie "war games.!") 

I even worked for the National Weather Service as a NOAA Weather Radio Broadcaster in the 70's and used a triple bank of rat-a-tat TTY machines with punch tape.  We also had a new piece of very expensive equipment that had a CRT & Lazer printer that used ARPANET.  Ahh.  Those were the days!
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G8ZPX

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Tim, i had already assumed timung was the route cause and configured for static ip. The question remains why should the Flex be the odd one out? The laptop is fine (w7), the desktop is fine (w10) the om2000 is fine (embedded firmware), only the Flex need special treatment
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Tim - W4TME, Customer Experience Manager

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When Windows boots, DHCP is not the first network traffic that is sent.  Wireshark shows a LLMNR query and an ICMPv6 MLR message a full second before it begins trying to get an IPv4 IP address.  I suspect these packets are "waking up" the wireless bridge link for that particular host prior to the DHCP DISCOVERY packets being sent.

The FLEX-6000 is not running the IPv6 protocol and the first traffic it sends are the DHCP DISCOVERY packets.