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HSRP

Cisco Proprietary

  • UDP port 1985 (v6 2029)
  • Version 1, RFC 2281
  • Version 2, adds IPv6, no RFC

Version 1

  • No millisecond timers
  • Groups from 0 to 255
  • hello messages have virtual mac
  • 224.0.0.2
  • default timers: 3s / 10s

Version 2

  • Millisecond timers
  • Groups from 0 to 4095
  • Hello messages have src-mac
  • 224.0.0.102
  • ff02::66
  • address range: 0000.0C9F.F000 to 0000.0C9F.FFFF

Example

R3# show standby brief
                     P indicates configured to preempt.
                     |
Interface   Grp  Pri P State   Active          Standby         Virtual IP
Gi0/0       34   100   Standby 192.168.34.4    local           192.168.34.34

Config

interface GigabitEthernet0/0
 ip address 192.168.34.3 255.255.255.0
 standby 34 ip 192.168.34.34
 ipv6 address 2001:DB8:0:34::3/64

References

Hot Standby Router Protocol - Wikipedia

Last Modified • Tuesday, June 9, 2026. 11:22 pm UTC+00:00 • Commit: 4b2315b