[TriLUG] dhcp from multiple waps

Joseph Mack NA3T jmack at wm7d.net
Sat Apr 5 14:03:11 EDT 2008

I've got a bunch of waps on the same network, allowing 
roaming, running DD-WRT (or similar) and I want the clients 
to dhcp. I don't need DNS for the client's name/IP (ie I 
don't need dhcpd to update named). WAP coverage overlaps so 
I can pull out any single WAP without clients loosing 

Currently I'm handling dhcp on the router. Can I handle 
dhcp on the waps? Problems I see are:

If I turn on dhcpd on each wap and give each dhcpd a subset 
of the IP space then when the client moves to a new wap, and 
gets a new IP, its tcpip sessions will be lost.

If I turn on dhcpd on only one wap, and hope that the dhcp 
calls make it around the network, then when that wap dies or 
is taken off-line, there's no more dhcpd.

There is redundant dhcpd, where two dhcpds on a network 
cooperate to hand out IPs in the same address space (it's 
not called "cooperative", maybe parallel, I forget). I've 
had this running at home, but it never worked well. After a 
few 100 dhcp leases were served, one server would wind up 
thinking that the other server had all the leases (even 
though it didn't) and wouldn't hand out any leases at all. I 
had to shutdown the dhcpds, clear the leases files and start 
again. Postings to the dhcpd mailing list didn't help and I 
found that it was a long standing problem (several years). 
As well I don't know if the dhcpd on DD-WRT can do 
cooperative dhcpd.

Any suggestions?

Thanks Joe

Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!

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