Filter
Top Products
42-6
Catalyst 3750 Switch Software Configuration Guide
OL-8550-09
Chapter 42 Configuring HSRP
Configuring HSRP
HSRP Configuration Guidelines
Follow these guidelines when configuring HSRP:
• HSRP for IPv4 and HSRP for IPv6 are mutually exclusive. You cannot enable both at the same time.
• HSRPv2 and HSRPv1 are mutually exclusive. HSRPv2 is not interoperable with HSRPv1 on an
interface and the reverse.
• You can configure up to 32 instances of HSRP groups.
If you configure the same HSRP group number on multiple interfaces, the switch counts each
interface as one instance:
For example, if you configure HSRP group 0 on VLAN 1 and on port 1, the switch counts this as
two instances.
• In the configuration procedures, the specified interface must be a Layer 3 interface:
–
Routed port: a physical port configured as a Layer 3 port by entering the no switchport
interface configuration command.
–
SVI: a VLAN interface created by using the interface vlan vlan_id global configuration
command and by default a Layer 3 interface.
–
EtherChannel port channel in Layer 3 mode: a port-channel logical interface created by using
the interface port-channel port-channel-number global configuration command and binding
the Ethernet interface into the channel group. For more information, see the “Configuring
Layer 3 EtherChannels” section.
• All Layer 3 interfaces must have assigned IP addresses. See the “Configuring Layer 3 Interfaces”
section on page 12-25 section.
• Configure only one instance of an FHRP. The switches support HSRPv1, HSRPv2, and HSRP for
IPv6.
• The version of an HSRP group can be changed from HSRPv2 to HSRPv1 only if the group number
is less than 256.
• When configuring group numbers for HSRPv2 and HSRP, you must use group numbers in ranges
that are multiples of 256. Valid ranges are 0 to 255, 256 to 511, 512 to 767, 3840 to 4095, and so on.
Examples of valid and invalid group numbers:
–
If you configure groups with the numbers 2, 150, and 225, you cannot configure another group
with the number 3850. It is not in the range of 0 to 255.
–
If you configure groups with the numbers 520, 600, and 700, you cannot configure another
group with the number 900. It is not in the range of 512 to 767.
• If you change the HSRP version on an interface, each HSRP group resets because it now has a new
virtual MAC address.
Enabling HSRP
The standby ip interface configuration command activates HSRP on the configured interface. If an IP
address is specified, that address is used as the designated address for the Hot Standby group. If no IP
address is specified, the address is learned through the standby function. You must configure at least one
Layer 3 port on the LAN with the designated address. Configuring an IP address always overrides
another designated address currently in use.