Table of Contents
Advertisement
Order of Preference in Determining the Local Address Pool for Allocating Prefixes
Order of Preference in Allocating Prefixes and Assigning DNS Addresses to Requesting Routers
Copyright © 2010, Juniper Networks, Inc.
links in the home network. The address allocation mechanism in the subscriber network
can be performed using ICMPv6 neighbor discovery in router advertisements, DHCPv6,
or a combination of these two methods.
When PE1 receives a request for prefix delegation from CPE1, PE1 assigns prefixes from
the list of unallocated prefixes in the IPv6 local pool.
You can configure multiple local address pools on a virtual router. When multiple pools
are configured, the pool that is used to allocate the prefix to the requesting router is
selected using the following order of preference: If a pool name is returned by the RADIUS
server in the Framed-IPv6-Pool attribute, that pool is used to delegate the prefix to the
client.
If the RADIUS server does not return a pool name in the Framed-IPv6-Pool attribute,
the pool name configured in the AAA domain map is used.
If no local address pool name is configured in the AAA domain map, the IPv6 address
of the interface on which the request was received is used to determine the pool.
If the interface address matches with any of the prefix ranges configured in the IPv6
local address pool on the router, that pool is used to delegate the prefix to the client.
Prefix delegation can be configured at the interface level and at the router level. Also,
certain VSA attributes returned in the RADIUS Access-Accept message from the
authentication server can impact the selection of the prefix to be assigned to the
requesting router. The level of preference attached to each of these prefix delegation
configurations is crucial. The delegating router uses the following order of preference to
determine the source from which the DHCPv6 prefix is delegated to the requesting router
from the DHCPv6 server:
An interface that is configured for prefix delegation is given priority over the RADIUS
1.
attributes returned in the Access-Accept message or the prefixes configured in the
IPv6 local address pool on the delegating router.
The RADIUS server might return one or more of the following attributes in the
2.
Access-Accept message in response to the client authentication request:
Ipv6-NdRa-Prefix (VSA 26-129)
Framed-IPv6-Prefix (RADIUS IETF attribute 97)
Delegated-IPv6-Prefix (RADIUS IETF attribute 123)
Framed-IPv6-Pool (RADIUS IETF attribute 100)
If any of the first three attributes are returned, then the prefix contained in those
attributes is used and the pool name in the Framed-IPv6-Pool attribute is ignored.
For example, if both the Delegated-IPv6-Prefix or Framed-IPv6-Prefix, and
Framed-IPv6-Pool attributes are returned from the RADIUS server, the DHCPv6
Chapter 1: Configuring Remote Access
103
Advertisement
Table of Contents
Troubleshooting
