HSRP Helper
Derive the HSRP virtual MAC, hello multicast address, and UDP port for version 1 or 2, IPv4 or IPv6, and check the group and timers.
This tool handles input and primary processing in your browser and is designed not to send the input to QuickKit’s server.
Result
| Virtual MAC | — |
|---|---|
| Group (hex) | — |
| Priority | — |
| Hello multicast address | — |
| UDP port | — |
| Hello timer | — |
| Hold timer | — |
How it works
HSRP is a Cisco-proprietary first-hop redundancy protocol. Choose the version (1 or 2), address family (HSRP for IPv6 requires version 2), group number, priority (0–255, default 100), and optionally the hello and hold timers (defaults 3 s and 10 s). The tool builds the virtual MAC — 0000.0C07.AC{gg} for v1 IPv4, 0000.0C9F.F{ggg} for v2 IPv4, 0005.73A0.0{ggg} for v2 IPv6, with the group as the trailing hex digits — and shows the hello multicast address and UDP port (224.0.0.2 for v1; 224.0.0.102 / UDP 1985 for v2 IPv4; FF02::66 / UDP 2029 for v2 IPv6). Version 1 allows groups 0–255; version 2 allows 0–4095. Timers are handled per version. HSRPv1 (RFC 2281) carries Hellotime and Holdtime as 1-octet second values, so this tool accepts 1–255 s; RFC 2281 requires the hold time to be greater than the hello time (enforced as an error) and recommends it be at least three times the hello time (a warning). HSRPv2 advertises and learns millisecond timer values (`standby timers msec …`); this whole-second tool does not model those, so it only checks that v2 values are positive whole seconds — it applies no protocol maximum, and for v2 the hold-time relationship (greater than hello, ≥ 3× hello) is shown as a warning because no HSRPv2 protocol requirement is documented. Specific IOS / IOS XE / IOS XR releases set their own configurable ranges; check your platform. The higher priority becomes active; without `preempt`, a router that recovers stays standby until the current active router fails. This tool does not connect to a device — verify against your platform and release.