DHCP Server on an Wireless Bridge

Simon Hobson dhcp1 at thehobsons.co.uk
Wed Feb 6 07:41:17 UTC 2008

Vincent Arniego wrote:

>[va] This is the equipment, it can be a bridge or an access point.


>  >Have you contacted the vendor to see if this "feature" can be turned
>  >off and the device made into a real bridge ?

>[va] Actually, we asked the vendor to make this as it is a translated bridge.
>We are currently serving around 300K subs as of today, and not 
>making it translated will be
>an inventory nightmare. Somehow by translating the layer 2 mac of 
>the device, we are able to determine which antennas are still 
>active. Oh yeah, why not use the uniqueness of the PC mac? Because 
>its not unique.
>There are NIC's that somehow have the same MAC. And that's the same 
>reason, why I would like to use the bridge's MAC as DHCP lease basis.

May I suggest you have your priorities the wrong way round ? It 
sounds like you are deliberately breaking stuff and then complaining 
when other stuff doesn't work !

Duplicate MACs - yes it happens (rarely), so track down the 
subscriber(s) and have them fix their kit. Not sure who they are (you 
SHOULD know) then just block that MAC and wait till they ring you !

And as for monitoring base station usage - try management tools. I'd 
be REALLY surprised if these units don't have some very useful values 
available by SNMP, I'd be even more surprised if one of these didn't 
allow you to monitor number of users. In a situation like that, I'd 
be looking to collect and store that information as part of the 
management process (look at graph, see number of subscribers going 
up, alert management that a base is heading for overload - for 

>Can you put a relay device behind the bridge and use that to forward
>the dhcp requests? For example, using a router or a computer running
>dhcrelay? Can the "bridge" function as a dhcp relay? Can you tell us
>what vendor/model the "bridge" is?
>[va] Motorola Canopy, option 82 is not yet built in, but we might 
>ask them to include it.

That wasn't the question ! But now we see what the bridge is doing, 
we can see that the answer is no.

OK, supplementary question - how do you identify subscribers ? As in, 
how do you admit only those people that are paying you for (or are 
authorised to use) the service ?

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