Chapter 44
Configuring HSRP
Figure 44-1
HSRP Versions
The switch supports these HSRP versions:
•
•
OL-21521-01
Typical HSRP Configuration
Host B
172.20.130.5
Active
router
172.20.128.1
Router A
172.20.128.32
Host C
HSRPv1—Version 1 of the HSRP, the default version of HSRP. It has these features:
The HSRP group number can be from 0 to 255.
–
HSRPv1 uses the multicast address 224.0.0.2 to send hello packets, which can conflict with
–
Cisco Group Management Protocol (CGMP) leave processing. You cannot enable HSRPv1 and
CGMP at the same time; they are mutually exclusive.
HSRPv2—Version 2 of the HSRP has these features:
To match the HSRP group number to the VLAN ID of a subinterface, HSRPv2 can use a group
–
number from 0 to 4095 and a MAC address from 0000.0C9F.F000 to 0000.0C9F.FFFF.
HSRPv2 uses the multicast address 224.0.0.102 to send hello packets. HSRPv2 and CGMP
–
leave processing are no longer mutually exclusive, and both can be enabled at the same time.
HSRPv2 has a different packet format than HRSPv1.
–
A switch running HSRPv1 cannot identify the physical router that sent a hello packet because
the source MAC address of the router is the virtual MAC address.
Virtual
Standby
router
router
172.20.128.3
Router B
Host A
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
Understanding HSRP
172.20.128.2
172.20.128.55
44-3