On 2014-06-30 14:06, Henning Brauer wrote: >> FWIW, I don't use carppeer even though it could save me substantial IP address space, for a couple of reasons: 1) I want the canary-in-the-coal-mine to inform me of any layer 2 weirdness 2) I prefer predictability and "normal" use cases 3) if I ever stop using CARP and switch to HSRP or VRRP, I'll need those addresses again > > you are creating massive confusion here regarding carppeer and > unnumbered carpdevs - those really have nothing to do with each other. > > That said, I do use unnumbered carpdevs in some cases and places. > > If carp0 has 10.0.0/24, and carp0 is backup on nodeX, nodeX might not > be able to reach 10.0.0/24. No more, no less. Can hurt, esp when the > default gateway is in that net, but is perfectly fine in many cases.
Whoops, you're right - I fixed a few errors in my email before sending, but missed those ones. #1 is somewhat valid - using carppeer would prevent me from learning that multicast was broken. I'm not sure how it could ever break on a L2 VLAN, but still... #2 is somewhat valid - using carppeer isn't the typical scenario. Nor is using carpdev, although I have the impression that use of carpdev (and therefore only needing 1 IP address) is increasing. #3 really has nothing to do with carppeer, unless I deliberately used addresses "foreign" to that interface/subnet, which would probably be silly, but could be another way around needing 3 IPs in the same subnet to implement CARP. Using carpdev is a much more sensible option to avoid IP address proliferation with CARP. -Adam
