DHCP failover doesn't receive DHCP requests in secondary server

Philippe Maechler plcmaechler at gmail.com
Thu Aug 16 15:04:08 UTC 2018

I saw it recently in the release notes.

*split bits;*

*The split statement specifies the split between the primary and secondary
for the purposes of load balancing. Whenever a client makes a DHCP request,
the DHCP server runs a hash on the client identification, resulting in
value from 0 to 255. This is used as an index into a 256 bit field. If the
bit at that index is set, the primary is responsible. If the bit at that
index is not set, the secondary is responsible. The split value determines
how many of the leading bits are set to one. So, in practice, higher split
values will cause the primary to serve more clients than the secondary.
Lower split values, the converse. Legal values are between 0 and 256
inclusive, of which the most reasonable is 128. Note that a value of 0
makes the secondary responsible for all clients and a value of 256 makes
the primary responsible for all *

Source: https://www.isc.org/wp-content/uploads/2018/02/dhcp44.html

On Thu, 16 Aug 2018 at 16:23, Anders Löwinger <anders at abundo.se> wrote:

> On 8/15/18 6:19 PM, Philippe Maechler wrote:
> > iirc with the latest patch, only the primary server replies to clients
> > when the split value is set to 255
> When was this added?
> /Anders
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