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I'm trying to get a wireless link set up to a building about 1/2 mile away from the rest of my network. I'm using a pair of Engenius EOC2611P radios, and as far as I can tell everything is set up correctly. While in the remote building, my laptop works great. I'm there now, and I have a YouTube video playing in the background in HD as I write this. However, I can't get any "mobile" devices to get IP addresses. I've tested with an iPad 3, Kindle Fire, and at least three different kinds of smart phones. So far, only my laptop works. If I put a static IP address into the iPad, it's able to use the network just fine.

What do I need to do so that devices in the remote building can get IP valid addresses from our dhcp server?

Here's the network information:

Main network

  • Windows 2008 R2 DNS/DHCP Server (10.1.1.11)
    • 10.0.0.0/8 Scope for vlan 1 (Core network)
    • 192.168.7.0/24 Scope for vlan 3 (vlan 3 intended for remote building)
      • 192.168.7.1-26 excluded from scope, will not be distributed
    • Several other scopes for various purposes, have worked for years (listed to show this isn't our only/first time using vlans)
  • HP 5406zl core switch (10.1.1.1)
    • Connects directly to dhcp server
    • Rules to forward dns/dhcp traffic on vlan 3 to 10.1.1.11 (like Cisco ip helper-address, works for other vlans)
    • 192.168.7.1 virtual interface for vlan 3
  • Managed Switch in building nearest remote site
    • Connected to core switch via 1Gbps fiber link
    • fiber link tagged for vlan 3 at both ends
    • Engenius EOC2611P (10.1.1.249)
      • Directional antenna pointed at new building
      • Configured as access point
      • Port on switch is untagged/PVID vlan 1, tagged for vlan 3
      • Hidden SSID configured for 802.1q vlan separation, tags packets with vlan 3
      • This configuration scheme is used successfully to give vlan-specific addresses in numerous other access points on our network
      • My expectation is that everything the other side of this SSID will not use vlans, have 192.168.7.0/24 subnet

Remote Network

  • Engenius EOC2611P configured as Client Bridge (192.168.7.6)
    • Connects fine to other EOC2611P, good signal strength
  • 8-port switch (192.168.7.7)
    • Wired to EOC2611P
    • Limited 802.1q vlan support, but I'm not using it: all one vlan on this side of bridge
    • No dhcp server
  • Engenius ECB9500 AP (192.168.7.4)
    • Wired to 8-port switch
    • "YCHolthus" SSID
    • No security
    • dhcp server only available in router mode, will not distribute dns info

Other Info
My laptop connects to the YCHolthus SSID, gets an address just fine, internet works
My laptop connects via cat5 direct to switch, get an address, internet works
My laptop is able to connect to both EOC2611P devices from the remote site
An iPad, Kindle Fire, and 3 different smart phones all fail to get an address
If I manually enter an address in the iPad for the YCHolthus SSID, it can use the internet
DHCP Server only lists leases for my laptop

When I get this much working, I'll add another access point (different make), two wired pcs, and a wired network printer to the switch at the remote location, and secure the SSID

I'm tempted to see if I have another switch available with adequate dhcp support, and then disable dhcp for that scope on our normal dhcp server, but I'd really prefer to use the existing dhcp server.

Update
DHCP logs on the server have two mentions of the iPad's MAC address during the period I was testing, though I made many more connection attempts. Both mentions are NACKS for the wrong subnet:

Line 37232: 15,10/30/13,14:23:00,NACK,192.168.40.38,,4CB19930D3C3,,0,6,,,
Line 37233: 15,10/30/13,14:23:00,NACK,192.168.40.38,,4CB19930D3C3,,0,6,,,

That address belongs to a different vlan on our network. I'm not sure why these would reach the server, but not others.

  • 2
    Can you run some packet traces on the DHCP server to see if the DHCP requests from the non-working clients are even making it to the server? – Brett Lykins Oct 30 '13 at 23:10
  • I can run a packet trace if I need to, but I try to avoid installing pcap on my production Windows servers. I see three potential scenarios (no requests reach server, requests reach server with an offer that's never ACK'd, and requests reach the server with no offer). What would you do to address each? – Joel Coehoorn Oct 31 '13 at 13:29
  • 1
    If you don't want to install pcap on the server you could mirror the traffic of the windows server to another port, where you will connect another device running wireshark to capture the dhcp packets. serverfault.com/questions/301156/… – trendy Oct 31 '13 at 13:42
  • @trendy - exactly, there isn't a need to actually touch the production servers and introduce any other risks/factors into this. Joel, I can't offer you solutions to each as the second two are outside my area of expertise, I am no Windows guy. But knowing which of these is happening is the first step in finding a solution. However, if the requests are not reaching the server, my gut would say that something in the Engenius EOC2611P bridge isn't forwarding the requests appropriately. But without more information, speculation is moot. – Brett Lykins Oct 31 '13 at 14:03
  • Also, check your DHCP logs. They might be able to tell you most of what you need to know (particularly, whether DHCPDISCOVER is showing up). – chrylis -on strike- Oct 31 '13 at 14:06
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This sounds like broken broadcast to me.

First, the fact that your laptop works is maybe due to how Windows tend to do strange things with DHCP, like trying a unicast DHCPREQUEST with its previous lease to try to renew it. I assume that it only works in your case because you always connect to the main site before connecting to the remote site, or your laptop was never connected to another network. Try connecting a laptop that has never seen the main network before, or use a LiveCD. I would expect it to not work.

Either fix/configure your wireless bridge to support broadcast (I would look at the AP side, you maybe have to register the client bridge or something) or deploy a DHCP relay on your remote site.

  • I have a dhcp relay on the remote site now. – Joel Coehoorn Nov 13 '13 at 17:01
  • @JoelCoehoorn hi so you configured dhcp relay on the switches at the remote site and got this to work? – allwynmasc Nov 7 '15 at 7:33
  • @allwynmasc Not exactly... I should have said "server" rather than "relay". The remote site has it's own scope, so I turned off the scope on our main dhcp server and put an old but lightly used laptop there running dhcp on ubuntu to handle dhcp. – Joel Coehoorn Nov 8 '15 at 2:56

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