Cisco Cisco IOS Software Release 12.4(4)T Données agrégées
Product Bulletin
© 2009 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information.
Page 12 of 299
DHCPv6 Client, Server, and Relay Functions
The DHCPv6 client, server, and relay functions are mutually exclusive on an interface.
Client Function
The DHCPv6 client function can be enabled on individual IPv6-enabled interfaces and benefits
from the new following features:
from the new following features:
●
Support for multiple IPv6 addresses (IA_NA options) on an interface
●
Rapid Commit: The Rapid Commit option is supported
●
The DHCPv6 Client works in an IPv6 VRF environment
Server Selection
A DHCPv6 client builds a list of potential servers by sending a solicit message and collecting
advertise message replies from servers. These messages are ranked based on preference value,
and servers may add a preference option to their advertise messages explicitly stating their
preference value. If the client needs to acquire prefixes from servers, only servers that have
advertised prefixes are considered.
advertise message replies from servers. These messages are ranked based on preference value,
and servers may add a preference option to their advertise messages explicitly stating their
preference value. If the client needs to acquire prefixes from servers, only servers that have
advertised prefixes are considered.
Server Function
The DHCPv6 server function can be enabled on individual IPv6-enabled interfaces.
The DHCPv6 server is providing the following features:
●
RFC3041 Compliance: IPv6 addresses will be allocated in a non-sequential fashion
●
Allocating multiple IPv6 addresses to a client. (ie: if multiple address pools apply, then one
address will be allocated from each address pool)
address will be allocated from each address pool)
●
Rapid Commit: The Rapid Commit option is supported
●
The DHCPv6 server works in an IPv6 VRF environment
●
The DHCPv6 server writes current allocated addresses to a TFTP server and can read
currently allocated addresses back from the TFTP server upon startup
currently allocated addresses back from the TFTP server upon startup
●
Configuration and support of Vendor-Specific Options
DHCP Relay Agent
A DHCP relay agent, which may reside on the client's link, is used to relay messages between the
client and server. DHCP relay agent operation is transparent to the client. A client locates a DHCP
server using a reserved, link-scoped multicast address. Therefore, it is a requirement for direct
communication between the client and the server that the client and the server be attached to the
same link. However, in some situations in which ease of management, economy, or scalability is a
client and server. DHCP relay agent operation is transparent to the client. A client locates a DHCP
server using a reserved, link-scoped multicast address. Therefore, it is a requirement for direct
communication between the client and the server that the client and the server be attached to the
same link. However, in some situations in which ease of management, economy, or scalability is a