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40-6
Catalyst 3560 Switch Software Configuration Guide
OL-8553-06
Chapter 40 Configuring HSRP
Configuring HSRP
• 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.
• 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 for IPv6, 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.
When the standby ip command is enabled on an interface and proxy ARP is enabled, if the interface’s
Hot Standby state is active, proxy ARP requests are answered using the Hot Standby group MAC
address. If the interface is in a different state, proxy ARP responses are suppressed.
Beginning in privileged EXEC mode, follow these steps to create or enable HSRP on a Layer 3 interface:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
interface interface-id Enter interface configuration mode, and enter the Layer 3 interface on
which you want to enable HSRP.