Hsrp Versions; Hsrp Authentication; Hsrp Messages; Hsrp Load Sharing - Cisco Nexus 3000 Series Configuration Manual

Information About HSRP
S e n d d o c u m e n t c o m m e n t s t o n e x u s 3 k - d o c f e e d b a c k @ c i s c o . c o m
HSRP version 2 uses the new IP multicast address 224.0.0.102 to send hello packets instead of the
multicast address of 224.0.0.2, which is used by version 1. HSRP version 2 permits an expanded group
number range of 0 to 4095 and uses a new MAC address range of 0000.0C9F.F000 to 0000.0C9F.FFFF.

HSRP Versions

Cisco NX-OS supports HSRP version 1 by default. You can configure an interface to use HSRP version
2.
HSRP version 2 has the following enhancements to HSRP version 1:
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When you change the HSRP version, Cisco NX-OS reinitializes the group because it now has a new
virtual MAC address.
HSRP version 2 has a different packet format than HSRP version 1. The packet format uses a
type-length-value (TLV) format. HSRP version 2 packets received by an HSRP version 1 router are
ignored.

HSRP Authentication

HSRP message digest 5 (MD5) algorithm authentication protects against HSRP-spoofing software and
uses the industry-standard MD5 algorithm for improved reliability and security. HSRP includes the IPv4
address in the authentication TLVs.

HSRP Messages

Routers that are configured with HSRP exchange the following three types of multicast messages:
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HSRP Load Sharing

HSRP allows you to configure multiple groups on an interface. You can configure two overlapping IPv4
HSRP groups to load share traffic from the connected hosts while providing the default router
redundancy expected from HSRP.
configuration.
Cisco Nexus 3000 Series NX-OS Unicast Routing Configuration Guide, NX-OS Release 5.0(3)U1(1)
12-4
Expands the group number range. HSRP version 1 supports group numbers from 0 to 255. HSRP
version 2 supports group numbers from 0 to 4095.
For IPv4, uses the IPv4 multicast address 224.0.0.102 to send hello packets instead of the multicast
address of 224.0.0.2, which is used by HSRP version 1.
Uses the MAC address range from 0000.0C9F.F000 to 0000.0C9F.FFFF for IPv4. HSRP version 1
uses the MAC address range 0000.0C07.AC00 to 0000.0C07.ACFF.
Adds support for MD5 authentication.
Hello—The hello message conveys the HSRP priority and state information of the router to other
HSRP routers.
Coup—When a standby router wants to assume the function of the active router, it sends a coup
message.
Resign—A router that is the active router sends this message when it is about to shut down or when
a router that has a higher priority sends a hello or coup message.
Figure 12-2 shows an example of a load-sharing HSRP IPv4
Chapter 12 Configuring HSRP