- IPv6 Addressing and Basic Connectivity
- IPv6 Anycast Address
- IPv6 Switching: Cisco Express Forwarding and Distributed Cisco Express Forwarding Support
- Unicast Reverse Path Forwarding for IPv6
- IPv6 Services: AAAA DNS Lookups over an IPv4 Transport
- IPv6 MTU Path Discovery
- ICMP for IPv6
- ICMP for IPv6 Redirect
- IPv6 Neighbor Discovery
- IPv6 Neighbor Discovery Cache
- Enhanced IPv6 Neighbor Discovery Cache Management
- IPv6 Default Router Preference
- IPv6 Stateless Autoconfiguration
- IPv6 RFCs
IPv6 Anycast Address
An IPv6 anycast address is an address that is assigned to a set of interfaces that typically belong to different nodes. Anycast addresses are syntactically indistinguishable from unicast addresses, because anycast addresses are allocated from the unicast address space.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.
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.
Information About IPv6 Anycast Address
IPv6 Address Type: Anycast
An anycast address is an address that is assigned to a set of interfaces that typically belong to different nodes. A packet sent to an anycast address is delivered to the closest interface (as defined by the routing protocols in use) identified by the anycast address. Anycast addresses are syntactically indistinguishable from unicast addresses, because anycast addresses are allocated from the unicast address space. Assigning a unicast address to more than one interface makes a unicast address an anycast address. Nodes to which the anycast address is assigned must be explicitly configured to recognize that the address is an anycast address.
 Note |
Anycast addresses can be used only by a device, not a host, and anycast addresses must not be used as the source address of an IPv6 packet. |
The figure below shows the format of the subnet device anycast address; the address has a prefix concatenated by a series of zeros (the interface ID). The subnet device anycast address can be used to reach a device on the link that is identified by the prefix in the subnet device anycast address.
| Figure 1 | Subnet Device Anycast Address Format |
How to Configure IPv6 Anycast Address
Configuring IPv6 Anycast Addressing
DETAILED STEPS
Configuration Examples for IPv6 Anycast Address
Example: Configuring IPv6 Anycast Addressing
interface tunnel 0 tunnel mode ipv6ip 6to4 tunnel source ethernet1 ipv6 address 2001:0db8:1::1/64 ipv6 address 2002:0db8:6301::/128 anycast ! interface ethernet 1 ip address 10.0.0.1 255.255.255.0 ip address 192.88.99.1 255.255.255.0 secondary
Additional References
Related Documents
| Related Topic | Document Title |
|---|---|
| IPv6 addressing and connectivity |
IPv6 Configuration Guide |
| IPv4 addressing |
IP Addressing: IPv4 Addressing Configuration Guide |
| Cisco IOS commands |
|
| 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 |
|---|---|
| No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Technical Assistance
| Description | Link |
|---|---|
| The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for IPv6 Anycast 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 IPv6 Anycast Address |
| Feature Name | Releases | Feature Information |
|---|---|---|
| IPv6: Anycast Address |
12.2(25)SEA 12.2(25)SG 12.2(33)SRA 12.2(33)SXH 12.3(4)T 15.0(2)SG Cisco IOS XE Release 2.1 3.2.0SG |
An anycast address is an address that is assigned to a set of interfaces that typically belong to different nodes. Anycast addresses are syntactically indistinguishable from unicast addresses, because anycast addresses are allocated from the unicast address space. The following commands were introduced or modified: ipv6 address anycast, show ipv6 interface. |
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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