dhcrelay command line options not properly configured for some DHCP failover scenarios
Scenario: ISC DHCP failover, with one of the 2 servers in the failover association residing in a subnet that also serves clients. Currently, this subnet will be set by services.inc as an upstream subnet. This breaks DHCP failover, as the 2nd (out-of-network) server of the failover association will not be relayed DHCPDISCOVER packets from clients in said subnet, which is required for proper operation of ISC DHCP failover. If a subnet is both a client subnet and where a DHCP server resides, "-i" should be used instead of "-iu" or "-id". Patch (attached) fixes this issue, although a more PHP savvy person should definitely look it over. (I'm a Perl guy, not PHP.)
Please note, this type of configuration is fairly common in small site scenarios, with a larger hub site as a DHCP failover peer for multiple sites.