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    <title>IPv6 Stateless Autoconfiguration </title>
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<a name="wp1073129"> </a><h1 class="pTitle">
IPv6 Stateless Autoconfiguration

</h1>
<a name="wp1073131"> </a><p class="pBody">
All interfaces on IPv6 nodes must have a link-local address, which is automatically configured from the 
identifier for an interface and the link-local prefix FE80::/10. A link-local address enables a node to 
communicate with other nodes on the link and can be used to further configure the node.

</p>
<a name="wp1073132"> </a><p class="pBody">
Nodes can connect to a network and automatically generate site-local and global IPv6 address without 
the need for manual configuration or help of a server, such as a DHCP server. With IPv6, a router on the 
link advertises in router advertisement (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.  

</p>
<a name="wp1073143"> </a><p class="pBody">
A node on the link can automatically configure site-local and global IPv6 addresses by appending its 
interface identifier (64&#160;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 ICMP 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. 

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<hr /><br><p class="pBody">Copyright 2010-2013, Cisco Systems, Inc. All rights reserved.</p> 

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