VRRP Priority & Timer Helper

Enter the VRRP version, priority (1–255), VRID (1–255), and advertisement interval — whole seconds for VRRPv2, centiseconds for VRRPv3. VRRPv3 follows RFC 9568, which obsoletes RFC 5798 and renamed the forwarding router "Active" (formerly "Master") for inclusive terminology; its timers are Active_Adver_Interval and Active_Down_Interval. VRRPv2 follows RFC 3768, the historical v2 specification, and keeps the "Master" terms. Priority is a configured value: 255 is reserved for the router that owns the virtual IP address (the owner MUST use 255), and 1–254 is the configurable range for a non-owner router (default 100) — the RFCs call such a router a Backup, but it is still elected the forwarding router when its down timer fires. Priority 0 is not configurable: it is the value the current Active/Master sends in an Advertisement to signal that it has stopped participating, so it is not accepted as input here. Timers a Backup uses: Skew_Time and the down interval = (3 × advertisement interval) + Skew_Time. VRRPv2's Skew_Time is (256 − priority) / 256 seconds; VRRPv3 scales it by the advertisement interval — ((256 − priority) × Active_Adver_Interval) / 256 — and works in centiseconds. The virtual MAC is IANA's 00-00-5E-00-01-{VRID} for IPv4 and 00-00-5E-00-02-{VRID} for IPv6, with the VRID as the last octet (VRID 1–255). Election also depends on preemption, the advertisement interval actually learned from the current forwarder, and platform behaviour; this tool does no election, and the RFC 9568 state-machine errata corrections do not change this arithmetic.