lease limit 1 and Apple Mac Computers creates duplicate IP address
Matt Jenkins
matt at smarterbroadband.net
Thu Sep 12 23:11:19 UTC 2013
Config:
default-lease-time 600;
class "Canopy" {
match if ( (binary-to-ascii(16,8,":",substring(option
agent.circuit-id,0,3))="a:0:3e") );
spawn with option agent.remote-id;
lease limit 1;
}
shared-network "15-Wolf" {
#Wolf MGT IP Block for DHCP Matching.
subnet 10.128.128.0 netmask 255.255.255.0 {
}
# Public Range
subnet 173.195.180.128 netmask 255.255.255.240 {
option broadcast-address 173.195.180.143;
option routers 173.195.180.129;
option subnet-mask 255.255.255.240;
pool {
allow members of "Canopy";
range 173.195.180.131 173.195.180.142;
}
}
}
This is for deployment on a Canopy wireless network. The Access Point
does DHCP relay. The remote-id is each bridged CPE (Customer Premises
Unit). This prevents multiple devices behind the CPE from getting IP
addresses. So far this works well, however I found a major problem with
Apple Mac Computers.
I can reproduce both of the following situations. All result in a
duplicate IP address issues. All appear to be the fault of Apple Mac OS.
Has anyone else ever seen this or found a fix for it?
CPE connected to a switch.
1. Apple computer gets IP address then disconnects cable.
2. Lease expires.
3. Other non-Apple computer connects and gets same IP address.
4. Apple computer connects and is unable to get a lease. It then assigns
itself the original IP address it had. Now there is an IP conflict.
CPE connected to a switch.
1. Apple computer gets IP address then disconnects cable.
2. Lease expires.
3. Other non-Apple computer connects and gets a new IP address.
4. All other unused IP addresses are given out.
5. New CPE connects and customers computer gets IP address Apple
computer had. (This will be a different household)
6. Original Apple computer connects and is unable to get a lease. It
then assigns itself the original IP address it had. Now there is an IP
conflict.
Thanks,
- Matt
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