Failure of dhcp server failover

[Eugene Grosbein]

02.05.2016 1:13, Niall O'Reilly wrote:

>> Is it possible to assign more than one fixed-address to the same MAC
>> depending on vlan tag
>> without usage of classes?
>
> I think so, but details of your network topology may give problems.
> If the tuple (Mac address, relay IP address) is unique and trustworthy for each IP address you need to assign, there is a simple solution without needing failover or classes. In this case, you'll need either
>
> (a) multiple fixed-address values in the host { } declaration, or
>
> (b) multiple host { } declarations, each with the same MAC address, but with its own distinct name and IP address.
>
> The DHCP relay will insert its own IP address as gwaddr to identify the originating (v)LAN, and each DHCP server will select a host declaration with matching fixed-address. ISC DHCP server can't do anything useful with dot1q tags.
>
> With either of these approached, you must duplicate the host declaration on the different DHCP servers. With multiple host declarations, each needs a unique name, which needn't match anything in the DNS.

Thank you, this is interesting. But in my case all requests from single AP came with the same gwaddr,
so tuples (MAC address, relay IP address) are not unique, they are the same for requests
coming from distinct vlans. That is, same DHCP relay processes requests from multiple vlans
and inserts same gwaddr into them.