Karl Auer wrote:
They're trivial once you're storing leases in a transactional database.
With all due respect, Arran, no, they are not.
Two DHCP servers in a failover relationship must communicate with each other, each maintaining information about the state of leases that the other has.
There's a miscommunication here. Arran is talking about two servers sharing a common view of their leases, and synchronizing that view with each other, to maintain a consistent response to client machines. You're talking about the ISC fail-over protocol. The two views just don't meet.
If they do so via a shared database (which seems to be what you are suggesting, apologies if not) then the entire point of failover is lost. And that is quite apart from the carefully timed state management that must occur during takeover or recovery in the case where a server drops out, is not reachable by its peer or is deliberately taken offline. Not to mention the possibility of having several servers participating in various failover relationships.
I disagree. Really. I spent most of a year working with DHCP in a previous life. Your comment is "correct", where the word "correct" has connotations of "theoretical analysis that conveniently ignores real-world situations". Like losing the entire d*mned lease database. Or working in settings like (1) enterprises, where 99.99% of lease renewals are for the same MAC/IP setting, or broadband/dial-up ISP's, who have interest in *not* handing out the same IP to the same MAC for any period of time,
No - not trivial.
90% of the situations are trivial to handle. The other 10% can go buy a $500,000 solution. The people selling the $500K solution are welcome to the support nightmare.
Hence my interest in how freeradius will be doing all this.
It will do it *very* well, or not at all. Alan DeKok.