- Preparing for Broadband Access Aggregation
- Providing Protocol Support for Broadband Access Aggregation of PPPoE Sessions
- PPP for IPv6
- DHCP for IPv6 Broadband
- Providing Protocol Support for Broadband Access Aggregation of PPP over ATM Sessions
- Providing Connectivity Using ATM Routed Bridge Encapsulation over PVCs
- PPPoE Circuit-Id Tag Processing
- Configuring PPP over Ethernet Session Limit Support
- PPPoE Session Limit Local Override
- PPPoE QinQ Support
- PPP-Max-Payload and IWF PPPoE Tag Support
- PPPoE Session Limiting on Inner QinQ VLAN
- PPPoE Agent Remote-ID and DSL Line Characteristics Enhancement
- Enabling PPPoE Relay Discovery and Service Selection Functionality
- Configuring Cisco Subscriber Service Switch Policies
- AAA Improvements for Broadband IPv6
- Per Session Queueing and Shaping for PPPoEoVLAN Using RADIUS
- 802.1P CoS Bit Set for PPP and PPPoE Control Frames
- PPP over Ethernet Client
- PPPoE Smart Server Selection
- Monitoring PPPoE Sessions with SNMP
- PPPoE on ATM
- PPPoE on Ethernet
- PPPoE over VLAN Enhancements Configuration Limit Removal and ATM Support
- ADSL Support in IPv6
- Broadband IPv6 Counter Support at LNS
- PPP IP Unique Address and Prefix Detection
- PPP IPv4 Address Conservation in Dual Stack Environments
- Broadband High Availability Stateful Switchover
- Broadband High Availability In-Service Software Upgrade
- Controlling Subscriber Bandwidth
- PPPoE Service Selection
- Disabling AC-name and AC-cookie Tags from PPPoE PADS
DHCP for IPv6 Broadband
The DHCP for IPv6 Broadband feature highlights the DHCP enhancements that support IPv6 broadband deployments. This feature briefly explains the different ways a delegating device selects prefixes for a requesting device, enabling accounting messages on a device, and forced release of delegated prefix bindings associated with a PPP virtual interface when the PPP virtual interface is terminated.
- Finding Feature Information
- Information About DHCP for IPv6 Broadband
- How to Configure DHCP for IPv6 Broadband
- Configuration Examples for DHCP for IPv6 Broadband
- Additional References
- Feature Information for DHCP for IPv6 Broadband
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.
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 DHCP for IPv6 Broadband
Prefix Delegation
An IPv6 prefix delegating device selects IPv6 prefixes to be assigned to a requesting device upon receiving a request from the client. The delegating device might select prefixes for a requesting device in the following ways:
-
Dynamic assignment from a pool of available prefixes.
-
Dynamic assignment from a pool name obtained from the RADIUS server.
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Assignment of prefix obtained from the RADIUS sever.
Contrary to IPv4 address assignment, an IPv6 user will be assigned a prefix, not a single address. Typically the Internet service provider (ISP) assigns a 64- or 48-bit prefix.
Accounting Start and Stop Messages
PPP calls a registry to allow DHCPv6 to append the delegated prefix information to accounting start and stop messages. When accounting is configured for a DHCPv6 pool, accounting interim packets are sent to broadband sessions after binding is provided from the pool.
Forced Release of a Binding
The DHCPv6 server maintains an automatic binding table in memory to track the assignment of some configuration parameters, such as prefixes between the server and its clients. The automatic bindings can be stored permanently in the database agent, which can be, for example, a remote TFTP server or local NVRAM file system.
DHCPv6 invokes a routine when the virtual interface used by PPP terminates. This routine automatically releases any delegated prefix bindings associated with the PPP virtual interface that is being terminated.
When a PPP virtual interface terminates, the routine runs through the full table of DHCPv6 bindings checking for the matching interface. Because PPP uses a virtual interface, this subroutine clears any related lease information when the PPP connection terminates.
 Note | In IPv6 broadband deployment using DHCPv6, you must enable release of prefix bindings associated with a PPP virtual interface using the ipv6 dhcp binding track ppp command. This ensures that DHCPv6 bindings are tracked together with PPP sessions, and in the event of DHCP REBIND failure, the client initiates DHCPv6 negotiation again. |
How to Configure DHCP for IPv6 Broadband
Enabling the Sending of Accounting Start and Stop Messages
1.
enable
2.
configure
terminal
3.
ipv6
dhcp
pool
poolname
4.
accounting
mlist
DETAILED STEPS
Removing Delegated Prefix Bindings
Perform this task to release any delegated prefix bindings associated with the PPP virtual interface that is being terminated.
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
ipv6
dhcp
bindings
track
ppp
DETAILED STEPS
Configuration Examples for DHCP for IPv6 Broadband
- Example: Enabling the Sending of Accounting Start and Stop Messages
- Example: Configuration for a Prefix Allocated from a Local Pool
Example: Enabling the Sending of Accounting Start and Stop Messages
This example shows how to enable a device to send accounting start and stop messages.
Device(config)# ipv6 dhcp pool pool1 Device(config-dhcp)# accounting list1
Example: Configuration for a Prefix Allocated from a Local Pool
DHCPv6 clients are connected to the DHCPv6 server on Gigabit Ethernet interface 0/0/0. The server is configured to use parameters from the DHCP pool called dhcp-pool. This pool provides clients with the IPv6 address of a DNS server and the domain name to be used. It also specifies that prefixes can be delegated from the prefix pool called client-prefix-pool1. The prefixes delegated will have valid and preferred lifetimes of 1800 and 600 seconds respectively. The prefix pool named client-prefix-pool1 has a prefix of length /40 from which it will delegate (sub) prefixes of length /48.
ipv6 dhcp pool dhcp-pool prefix-delegation pool client-prefix-pool1 lifetime 1800 600 dns-server 2001:DB8:3000:3000::42 domain-name example.com ! interface GigabitEthernet0/0/0 description downlink to clients ipv6 address FEC0:240:104:2001::139/64 ipv6 dhcp server dhcp-pool ! ipv6 local pool client-prefix-pool1 2001:DB8:1200::/40 48
Additional References
Related Documents
Related Topic |
Document Title |
|---|---|
|
IPv6 addressing and connectivity |
IPv6 Configuration Guide |
|
Cisco IOS commands |
|
|
IPv6 commands |
Cisco IOS IPv6 Command Reference |
|
Cisco IOS IPv6 features |
Standards and RFCs
Standard/RFC |
Title |
|---|---|
|
RFCs for IPv6 |
IPv6 RFCs |
MIBs
|
MIB |
MIBs Link |
|---|---|
|
|
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 DHCP for IPv6 Broadband
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.|
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
DHCP Enhancements to Support IPv6 Broadband Deployments |
Cisco IOS XE Release 2.5 |
The feature highlights the DHCP enhancements that support IPv6 broadband deployments, such as, the different ways a delegating device selects prefixes for a requesting device, enabling accounting messages on a device, and forced release of delegated prefix bindings associated with a PPP virtual interface when the PPP virtual interface is terminated. The following commands were introduced or modified: accounting, ipv6 dhcp bindings track ppp, ipv6 dhcp pool. |
|
DHCPv6 Prefix Delegation RADIUS VSA |
Cisco IOS XE Release 2.5 |
When the user requests a prefix from the prefix delegator, typically the NAS, the prefix is allocated using DHCPv6. |
|
DHCP Accounting Attribute |
Cisco IOS XE Release 3.13S |
The DHCP Accounting Attribute feature allows DHCPv6 to append delegated prefix information to accounting start and stop messages. |
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