DHCP Static binding not working as expected??

chamara samarakoon chthsa123 at gmail.com
Sun Sep 9 15:17:04 UTC 2012


I am new to isc dhcp, and i am facing following situation , and need help
to understand,

I am having 3 devices called, A,B,C. On dhcp conf pool is restricted to *only
one IP*.
Also on dhcpd conf *static bind is enabled* for device A.

1.Plug device A to network -> with out issue device got IP

DHCPOFFER on to 00:20:d2:3a:51:69 via
Commit: IP: Mac: 0:20:d2:3a:51:69 Name:

2.Unplug device A and change the static conf MAC to B's MAC(Restart dhcpd
server) and Plug device B

No issue device B got IP,
DHCPOFFER on to 00:20:d2:39:24:f8 via
Commit: IP: Mac: 0:20:d2:39:24:f8 Name:

3. Replug the device A *with out removing device B*,
A received the IP even though B is having it, A's IP is active and B's IP
is not active.

DHCPDISCOVER from 00:20:d2:3a:51:69 via network
no free leases
Reclaiming abandoned lease
ICMP Echo reply while lease valid.
Abandoning IP address pinged before offer
DHCPDISCOVER from 00:20:d2:3a:51:69 via cancel load balance to
peer XXX - no free leases
DHCPDISCOVER from 00:20:d2:3a:51:69 via
DHCPOFFER on to 00:20:d2:3a:51:69 via
Commit: IP: Mac: 0:20:d2:3a:51:69 Name:

Why this is happening, I do not want DHCPD to offer the IP to another
device when it is bind on static file to another device.But strange thing
is when i plug device C when only device B(*same way as device A plug in
step 3 but this time not device A instead device C is used.*) is there , C
naver receive a IP as i expected.Help is very much appreciated,What is
happening with device A and B??

Thank You,

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