HSRP: Global IPv6 Address

Last Updated: October 19, 2012

IPv6 routing protocols ensure router-to-router resilience and failover. However, in situations in which the path between a host and the first-hop router fails, or the first-hop router itself fails, first hop redundancy protocols (FHRPs) ensure host-to-router resilience and failover.

The Hot Standby Router Protocol (HSRP) protects data traffic in case of a gateway failure.

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Information About HSRP Global IPv6 Address

HSRP Global IPv6 Address


Note


This feature is supported only in Cisco IOS Release 12.2(33)SXI4.

The HSRP global IPv6 address feature allows users to configure multiple nonlink local addresses as virtual addresses, and it allows for the storage and management of multiple global IPv6 virtual addresses in addition to the existing primary link-local address. If an IPv6 address is used, it must include an IPv6 prefix length. If a link-local address is used, it must not have a prefix.

The figure below depicts a deployment scenario that uses an HSRP IPv6 global virtual interface:

Figure 1 Scenario Using Gan HSRP IPv6 Global Virtual Interface


In the figure above, the provider equipment (PE) routers need to inject a route to reach the customer premises equipment (CPE) from the backbone routers. Because there are two CPEs, HSRP is convenient to use. The static route will be set with a link-local next hop (FE80::1:1:1:CAFE). If this address is injected in the backbone, this route is useless with a link-local next hop, as link-local addresses only have scope within the Layer 2 local LAN space. To address this issue, the next hop of the static route toward the virtual address must be set to a nonlink-local address, so backbone routers can route packets to the PE routers. At the next-hop address resolution, the active HSRP group member will reply to neighbor solicitation (NS) messages sent to the nonlink-local address.

How to Enable HSRP Global IPv6 Address

Enabling and Verifying an HSRP Group for IPv6 Operation

In this task, when you enter the standby ipv6 command, a modified EUI-64 format interface identifier is generated in which the EUI-64 interface identifier is created from the relevant HSRP virtual MAC address.

In IPv6, a router on the link advertises in RA messages any site-local and global prefixes, and its willingness to function as a default router for the link. RA messages are sent periodically and in response to router solicitation messages, which are sent by hosts at system startup.

A node on the link can automatically configure site-local and global IPv6 addresses by appending its interface identifier (64 bits) to the prefixes (64 bits) included in the RA messages. The resulting 128-bit IPv6 addresses configured by the node are then subjected to duplicate address detection to ensure their uniqueness on the link. If the prefixes advertised in the RA messages are globally unique, then the IPv6 addresses configured by the node are also guaranteed to be globally unique. Router solicitation messages, which have a value of 133 in the Type field of the ICMPv6 packet header, are sent by hosts at system startup so that the host can immediately autoconfigure without needing to wait for the next scheduled RA message.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 unicast-routing

4.    interface type number

5.    standby [group-number] ipv6 {ipv6-global-address | ipv6-address / prefix-length | ipv6-prefix / prefix-length | link-local-address | autoconfig

6.    standby [group-number] preempt [delay minimum seconds | reload seconds | sync seconds}]

7.    standby [group-number] priority priority

8.    exit

9.    show standby [type number [group]] [all | brief

10.    show ipv6 interface [brief] [interface-type interface-number] [prefix


DETAILED STEPS
  Command or Action Purpose
Step 1
enable


Example:

Router> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Router# configure terminal

 

Enters global configuration mode.

 
Step 3
ipv6 unicast-routing


Example:

Router(config)# ipv6 unicast-routing

 

Enables the forwarding of IPv6 unicast datagrams.

  • The ipv6 unicast-routing command must be enabled for HSRP for IPv6 to work.
 
Step 4
interface type number


Example:

Router(config)# interface ethernet 0/0

 

Specifies an interface type and number, and places the router in interface configuration mode.

 
Step 5
standby [group-number] ipv6 {ipv6-global-address | ipv6-address / prefix-length | ipv6-prefix / prefix-length | link-local-address | autoconfig


Example:

Router(config-if)# standby 1 ipv6 autoconfig

 

Activates the HSRP in IPv6.

If an IPv6 address is used, it must include an IPv6 prefix length. If a link-local address is used, it must not have a prefix.

 
Step 6
standby [group-number] preempt [delay minimum seconds | reload seconds | sync seconds}]


Example:

Router(config-if)# standby 1 preempt

 

Configures HSRP preemption and preemption delay.

 
Step 7
standby [group-number] priority priority


Example:

Router(config-if)# standby 1 priority 110

 

Configures HSRP priority.

 
Step 8
exit


Example:

Router(config-if)# exit

 

Returns the router to privileged EXEC mode.

 
Step 9
show standby [type number [group]] [all | brief


Example:

Router# show standby

 

Displays HSRP information.

 
Step 10
show ipv6 interface [brief] [interface-type interface-number] [prefix


Example:

Router# show ipv6 interface ethernet 0/0

 

Displays the usability status of interfaces configured for IPv6.

 

Configuration Example for HSRP Global IPv6 Address

Example: Configuring HSRP Global IPv6 Addresses

This example shows three HSRP global IPv6 addresses with an explicitly configured link-local address:

interface Ethernet0/0
 no ip address
 ipv6 address 2001::DB8:1/64
 standby version 2
 standby 1 ipv6 FE80::1:CAFÉ 
 standby 1 ipv6 2001::DB8:2/64
 standby 1 ipv6 2001:DB8::3/64
 standby 1 ipv6 2001:DB8::4/64 
end

Additional References

Related Documents

Related Topic Document Title

IPv6 addressing and connectivity

IPv6 Configuration Guide

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IPv6 commands

Cisco IOS IPv6 Command Reference

Cisco IOS IPv6 features

Cisco IOS IPv6 Feature Mapping

Standards and RFCs

Standard/RFC Title

RFCs for IPv6

IPv6 RFCs

MIBs

MIB

MIBs Link

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

Technical Assistance

Description Link

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Feature Information for HSRP: Global IPv6 Address

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 1 Feature Information for HSRP: Global IPv6 Address
Feature Name Releases Feature Information

HSRP: Global IPv6 Address

12.2(33)SXI4

The HSRP global IPv6 address feature allows users to configure multiple non-link local addresses as virtual addresses.

The following command was introduced: standby ipv6.

Glossary

  • CPE --Customer premises equipment
  • FHRP --First hop redundancy protocol
  • GLBP --Gateway load balancing protocol
  • HSRP --Hot standby routing protocol
  • NA --Neighbor advertisement
  • ND --Neighbor Discovery
  • NS --Neighbor solicitation
  • PE --Provider equipment
  • RA --Router advertisement
  • RS --Router solicitation

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