DHCP failover and “secs” value

Abu Abdulla alhanbali montaqa at gmail.com
Tue Oct 23 07:34:26 UTC 2012


I’m trying to figure out the failover behavior in more details:

- For new user: DHCPDISCOVER (broadcast) will reach both servers.
Hashing will be done on the MAC and one server will respond based on
“split” value as far “secs” is less than the configured value. If
“secs” is more, then both servers will provide DHCPOFFER to the
client. User will choose one and send DHCPREQUEST (broadcast). If
“secs” is less than the configured value, only the server identified
in the DHCPREQUEST will respond with DHCPACK. If “secs” is more, both
will respond. How will the two servers sync this MAC between

- For a current user and in some cases, DHCP renew is sent to both
servers (broadcast). will the behavior be the same as above i.e.
depends on “secs” value.

- In many cases, one server will end up with more active leases than
the other one, balancing is done in a configurable way. How the lease
ownership is shifting from one server to the other one since the user
will continue to request from the same server he got the IP from.

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