Cannot get IP address via DHCP (PS2)

[EW]

Testing the PS2 in Station mode and the PC connected to the PS2 cannot get IP address via DHCP (static IP for PS2 and wireless client connected to the access point in which the PS2 is connected with can get IP via DHCP).

Any settings to be aware of?

Thanks!

[UBNT-Mike.Ford]

Hello EW,

Can you tell me what type of AP you are connecting to? Also can you please post your configuration file from the PS2?

Thanks,

Mike

[EW]

Hi Mike,

I have tested PS2 with Wavion, Motorola's MotoMesh Duo, Intermec 2101 & Cisco 1200.

The configuration of the PS2 I'm testing is:

users.status=enabled
radio.1.channel=1
ebtables.3.cmd=-t broute -A BROUTING --protocol 0x888e --in-interface ath0 -j DROP
ebtables.3.status=enabled
ebtables.2.cmd=-t nat -A POSTROUTING --out-interface ath0 -j arpnat --arpnat-target ACCEPT
ebtables.2.status=enabled
ebtables.1.cmd=-t nat -A PREROUTING --in-interface ath0 -j arpnat --arpnat-target ACCEPT
ebtables.1.status=enabled
ebtables.status=enabled
route.1.netmask=0
route.1.ip=0.0.0.0
route.1.gateway=10.11.8.1
route.1.devname=br0
route.1.status=enabled
route.status=enabled
dhcpc.1.devname=br0
dhcpc.1.status=disabled
dhcpc.status=disabled
dhcpd.1.status=disabled
dhcpd.status=disabled
netconf.3.up=enabled
netconf.3.netmask=255.255.255.0
netconf.3.ip=10.11.8.145
netconf.3.devname=br0
netconf.3.status=enabled
netconf.2.up=enabled
netconf.2.netmask=255.255.255.0
netconf.2.ip=0.0.0.0
netconf.2.devname=ath0
netconf.2.status=enabled
netconf.1.promisc=enabled
netconf.1.up=enabled
netconf.1.netmask=255.255.255.0
netconf.1.ip=0.0.0.0
netconf.1.devname=eth0
netconf.1.status=enabled
netconf.status=enabled
bridge.1.port.2.devname=ath0
bridge.1.port.1.devname=eth0
bridge.1.fd=1
bridge.1.devname=br0
bridge.status=enabled
wireless.1.rssi_led4=30
wireless.1.rssi_led3=22
wireless.1.rssi_led2=15
wireless.1.rssi_led1=1
wireless.1.hide_ssid=disabled
wireless.1.ssid=Wavion
wireless.1.security=none
wireless.1.devname=ath0
wireless.1.status=enabled
wireless.status=enabled
radio.1.tx_antenna=1
radio.1.rx_antenna=1
radio.1.tx_antenna_diversity=disabled
radio.1.rx_antenna_diversity=disabled
radio.1.ack.auto=enabled
radio.1.acktimeout=48
radio.1.txpower=1
radio.1.ieee_mode=g
radio.1.rate.auto=enabled
radio.1.rate.max=54M
radio.1.mode=managed
radio.1.devname=ath0
radio.1.status=enabled
radio.ratemodule=ath_rate_onoe
radio.countrycode=344
radio.status=enabled
httpd.port.http=80
httpd.status=enabled
users.1.password=VvpvCwhccFv6Q
users.1.name=ubnt
users.1.status=enabled
wireless.1.wds=disabled
wireless.1.macclone=disabled
radio.1.countrycode=344
radio.1.clksel=0
wireless.1.authmode=1
wireless.1.ap=
aaa.status=disabled
aaa.1.status=disabled
wpasupplicant.status=disabled
wpasupplicant.device.1.status=disabled
ppp.1.password=
ppp.status=disabled
ppp.1.status=disabled
iptables.status=disabled
resolv.nameserver.1.status=enabled
resolv.nameserver.1.ip=10.11.8.1
resolv.nameserver.2.status=disabled
resolv.nameserver.2.ip=
resolv.status=enabled
netmode=bridge
wireless.1.security.default_key=1
wireless.1.security.1.key=s:17168

DHCP works when only 1 PC is connected to the PS2 and with the MAC clone enabled.

Thanks,
EW

[UBNT-Mike.Ford]

Hello EW,

Can you set the unit into Sta/WDS mode with the AP in WDS mode for a test?

Thanks,

Mike

[EW]

Hi Mike,

The APs I tested do not support WDS mode (except Cisco 1200).

Do you mean to test with another PS2 in AP WDS mode?

I checked my DHCP server and found that the DHCP server got the request from the PC connected to PS2 (station mode) and assigned an IP to it, however the DHCP reply did not reach the PC.

Thanks.

[WHT]

Since WDS is not a certified application yet, there's no guarantee of interoperability between different manufacturers' radios.

So yes, you'd need UBNT products at both ends.

[rconaway]

This could also be a timing issue. We dealt with this with Enterasys and found that the latency between the DHCP server which was the router and the client was causing the problem. We changed DHCP servers, problem solved. Test with a window DHCP server and see what happens.

[bobcopro]

Am I missing something here? If the PS2 has a static IP address and you have a computer directly connected with it, why not just put in a static IP address into the computer and have the gateway and DNS set to whatever the source (DSL, cable modem, whatever) IP is on the other end?

If you want more than one computer connected to it you'll need a router anyways and can set it to the same static address as the computer was set for and let the router's DHCP server hand out addresses locally.

I am asking out of curiosity as that is how my system is setup and it allows me to know for sure the IP's of all the link segments so I can easily go to any part of the link and find out its status.

The only issue would be if there is a distant router handing out DHCP you'd need to make sure the local one is not handing out overlapping addresses in the same segment (ie - distant router hands out 1.2 through 1.100 and the local one hands out 1.101 through 1.199).

If there's an advantage to doing it another way I'd like to know as I'm always looking for something that might be easier or more dependable.

[rconaway]

In some environments, we would rather hand out IP addresses because not everyone is connected directly to a CPE. It's also typically easier on tech support if the person travels with the laptop. It's a challenge when you get rogue DHCP servers on the network as then you either have to track them down or suppress them.

[EW]

Hi Mike,

I tested with a pair of PS2 in the following configurations:

1. PS2(AP) --- PS2(Station) ---- PC (cannot obtain IP via DHCP);
2. PS2(AP WDS without selecting Auto) --- PS2(Station WDS) --- PC (can obtain IP via DHCP);
3. PS2(AP WDS with Auto selected) --- PS2(Station WDS) --- PC (can obtain IP via DHCP);

Would like to know the difference between AP -- Station & AP WDS -- Station WDS?

In summary, in my testings, PC connected to PS2(station mode) associated to different brand/model of AP cannot obtain IP via DHCP except with MAC clone.

Thanks,
EW

[UBNT-Mike.Ford]

Hello EW,

When using the units in WDS mode, it makes the link a full layer 2 transparent bridge. When in AP/STA the units will do some ARP nat, witch some DHCP routers do not like.

Thanks,

Mike

[EW]

Hi Mike,

Is there any means to make the DHCP works as we will be using PS2 with other APs (not Ubiquiti)?

Thanks,
EW

[UBNT-Mike.Ford]

Hello EW,

Sometimes setting static routes to the PS2 will work. I know this work with older versions of MirkoTik software and some Tranzeo stuff.

Thanks,

Mike

[EW]

Hi Mike,

Thanks. I just tested with OS v3.3.1 and got the same result.

The AP and PS2 (station mode) and the client are in the same subnet.

Any other suggestions?

Best Regards,
EW

[UBNT-Mike.Ford]

Hey EW,

I went through a few different setups here (all AP to STA with WDS disabled)

I was abled to DHCP without issue using Netgear, Linksys, Tranzeo and MikroTik routers.

Can you check your DHCP server config?

Thanks,

Mike