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swissiws
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WDS - DHCP server still an issue

Mon Apr 06, 2009 9:40 am

Hi All,

I am still trying to get an responds of my previous posting. I hope, this time i will be a bit better in explaining what i have/want to do:


MT 2.95 LEVEL 4

MT1:
(1 ETHER, 1 WLAN)

DHCP-SERVER (running on WDS bridge)
AP-BRIDGE (AP1 for clients)
WDS TO MT2 (dynamic)


MT2:
AP-BRIDGE (AP2 for clients)
WDS TO MT1 (dynamic)

Both radios are using same frequency as otherwise WDS will not work.

Now, my issue is the following: When a client sees both AP's, but the signal strengh of AP2 is better, it will not get an IP address assigned. When i check the DHCP server, the client is actually registered.When the client only sees AP2, the IP address is assigned correctly to the client.

It looks for me like somewhere the responding packets from the DHCP server get lost. Is this setup only possible to archive with 2 radios on each MT, one for WDS, one for AP for clients? . Any idea?

Thanks a lot for your help
 
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taglio
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Re: WDS - DHCP server still an issue

Mon Apr 06, 2009 12:15 pm

You can put two dhcp server with two different ip pool...
1: /ip pool add name=1 ranges=192.168.1.2-192.168.1.100
2: /ip pool add name=2 ranges=192.168.1.101-192.168.1.200
.mhavoc world
 
swissiws
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Re: WDS - DHCP server still an issue

Mon Apr 06, 2009 1:44 pm

do you mean, each AP should have a DHCP server running? What if I would end up with 20+ AP's? I rather would like to centralise services where i can.

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cmacneill
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Re: WDS - DHCP server still an issue

Mon Apr 06, 2009 2:03 pm

In the scenario you describe everything must be bridged for the DHCP connectivity to work. As you haven't quoted any IP addresses it's impossible to tell whether you are bridging or routing.

Regards

Chris Macneill
 
swissiws
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Re: WDS - DHCP server still an issue

Mon Apr 06, 2009 11:14 pm

Sorry Chris,

all is bridged, the

MT1 WDS-Bridge interface has IP 192.168.254.254/24

The MT1 ethernet interface has IP 192.168.2.1/24 and is not a member of the bridge ports, therefore routed

The DHCP server is running on the WDS-Bridge interface and the IP pool is 192.168.254.100-192.168.254.150


the
MT2 WDS-Bridge interface has IP 192.168.254.253/24


As I mentioned ealier, all is good as long as the AP client does not see both MT AP's. As it is bridged, it looks to me like the ap client is initially connecting to MT1 AP, then reconnects to MT2 AP. This all seems to happen while the client trys to assign a DHCP address. The client seems to end up with ARP table entries pointing MT2 Bridge interface as MT1 bridge interface to same MAC address .

It is absolutely strange. As i planning to roll out 20 AP's with WDS bridge, i believe this will be a major issue. I was looking in to HWMP+, but it seems not to work very well either.

The main issue i do have here is very dense bush, therefore, some AP's just will not see each other.

Any input is very much appreciated.

Thanks

Matt
 
cmacneill
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Re: WDS - DHCP server still an issue

Tue Apr 07, 2009 12:39 am

Here are a few things to try:-

Try upgrading to RouterOS v3.22, you're way behind on software version, you may well find this solves all your problems.

When I set-up my network in Scotland I used multiple virtual APs to separate the WDS traffic from the client traffic. However, if I remember correctly you need Atheros based radio cards, Prism chip sets don't or at least didn't support virtual APs.

A better solution is to have multiple physical radio cards, you can then have one frequency for WDS and separate frequencies for the client traffic. This solution also increases network capacity as the radio card isn't trying to do four things at once. Remember that a radio card can only receive or transmit, not both at the same time, so if it has to communicate with the client and the next node in the chain you end up with half the bandwidth capacity than if you use two or more radio cards at the AP.

However, if it's the client which is swapping APs I'm not sure that either option will make much difference. It sounds like some weird client end problem. It might be worth trying a different manufacturers radio card at the client end to see if that fixes it. You could also try using a more directional antenna at the client end which isolates one AP from the other.

Regards

Chris
 
swissiws
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Re: WDS - DHCP server still an issue

Wed Apr 08, 2009 2:39 am

Hi Chris,

well, i guess i forgot to mention i am using at the lab RB112...

1) configured VAP on both routers. The result was the same....

2) updated to version 3.22 on both routers. The DHCP problem is now solved (still taking its time while seeing both AP's, but its working.
The main issue with this version is, that i can not run hotspot on this routerboard without having the CPU spike to constant 100%. Uninstalled all unneeded packets. The router is running with DHCP,DNS,WDS and AP installed and configured on one radio at around 5-10%. As soon as hotspot packet is activated, the CPU constant 100%.

One more personal question:
As i see you are or have been based in NZ, can you recommend some distributors of antenna equipment eg, low loss cable, connectors etc, i could possibly use as I am based in Raro.

Thanks again.

Matt

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