DHCPv6 Local Address Pools for Allocation of IPv6 Prefixes Overview

In previous releases, you configured DHCPv6 local servers on a virtual router to delegate IPv6 prefixes to DHCPv6 clients. In this release, you can configure IPv6 local address pools to allocate IPv6 prefixes to clients in networks that use DHCPv6. These pools can be used to assign prefixes from a delegating router, which is an E Series router configured as a DHCPv6 local server, to the requesting router, which is the customer premises equipment (CPE) at the edge of the remote client site that acts as the DHCP client.

The DHCPv6 prefix delegation feature is useful in scenarios in which the delegating router does not have information about the topology of the networks in which the customer edge device or requesting router is located. In such cases, the delegating router requires only the identity of the requesting router to choose a prefix for delegation. An IPv6 local pool is configured on the delegating router, which contains information about the prefixes, their validity periods, and other parameters to control their assignment to the requesting routers. The delegating router is configured with a set of prefixes that is used to assign to a CPE or DHCPv6 client, when it first establishes a connection with an Internet service provider (ISP).

When the delegating router receives a request from a DHCPv6 client, it selects an available prefix and delegates it to the client. The DHCPv6 client subnets the delegated prefix and assigns the prefixes to links at the customer edge.

Keep the following points in mind when you configure IPv6 local address pools to assign prefixes to requesting routers:

When a PPP user establishes a PPP connection with the E Series router functioning as a remote access server, the subscriber is first authenticated using the RADIUS protocol. The Access-Accept message returned from the RADIUS server can contain different IPv6 attributes, including the Framed-IPv6-Pool attribute, which contains the name of the IPv6 pool from which a prefix needs to be assigned to the subscriber. The prefix is assigned to the subscriber using the DHCPv6 prefix delegation feature, which is covered in the next section.

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