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Implementing the Dynamic Host Configuration Protocol

Contents

Implementing the Dynamic Host Configuration Protocol

This module describes the concepts and tasks you will use to configure Dynamic Host Configuration Protocol (DHCP).

Feature History for Implementing the Dynamic Host Configuration Protocol

Release

Modification

Release 3.2

This feature was introduced.

Release 3.4.0

The DHCP IPv6 Information Pool configuration procedure was added and DCHP relay information description was updated.

Release 3.7.0

The DHCP CLI was modified.

Prerequisites for Configuring DHCP Relay Agent

The following prerequisites are required to configure a DHCP relay agent:


  • You must be in a user group associated with a task group that includes the proper task IDs. The command reference guides include the task IDs required for each command. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator for assistance.

  • A configured and running DHCP client and DHCP server

  • Connectivity between the relay agent and DCHP server

Information About DHCP Relay Agent

A DHCP relay agent is a host that forwards DHCP packets between clients and servers that do not reside on a shared physical subnet. Relay agent forwarding is distinct from the normal forwarding of an IP router where IP datagrams are switched between networks transparently.

DHCP clients use User Datagram Protocol (UDP) broadcasts to send DHCPDISCOVER messages when they lack information about the network to which they belong.

If a client is on a network segment that does not include a server, a relay agent is needed on that network segment to ensure that DHCP packets reach the servers on another network segment. UDP broadcast packets are not forwarded, because most routers are not configured to forward broadcast traffic. You can configure a DHCP relay profile and configure one or more helper addresses in it. You can assign the profile to an interface or a VRF.

Figure 1 demonstrates the process. The DHCP client broadcasts a request for an IP address and additional configuration parameters on its local LAN. Acting as a DHCP relay agent, Router B picks up the broadcast, changes the destination address to the DHCP server's address and sends the message out on another interface. The relay agent inserts the IP address of the interface, on which the relay profile into the gateway address (giaddr) field of the DHCP packet, which enables the DHCP server to determine which subnet should receive the offer and identify the appropriate IP address range. The relay agent unicasts the messages to the server address, in this case 172.16.1.2 (which is specified by the helper address in the relay profile).

Figure 1. Forwarding UDP Broadcasts to a DHCP Server Using a Helper Address

How to Configure and Enable DHCP Relay Agent

This section contains the following tasks:

Configuring and Enabling the DHCP Relay Agent

Configuring a DHCP Relay Profile

This task describes how to configure and enable the DHCP relay agent.

SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    profile profile-name relay

4.    helper-address [vrf vrf- name ] address

5.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Enters DHCP IPv4 configuration mode.

 
Step 3 profile profile-name relay


Example: 
RP/0/0/CPU0:router(config-dhcpv4)# profile client relay
 

Enters DHCP IPv4 profile relay submode.

 
Step 4 helper-address [vrf vrf- name ] address


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# helper-address vrf 
foo 10.10.1.1
 

Forwards UDP broadcasts, including BOOTP and DHCP.


  • The value of the address argument can be a specific DHCP server address or a network address (if other DHCP servers are on the destination network segment). Using the network address enables other servers to respond to DHCP requests.

  • For multiple servers, configure one helper address for each server.

 
Step 5 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Configuring the DHCPv6 (Stateless) Relay Agent

Perform this task to specify a destination address to which client messages are forwarded and to enable Dynamic Host Configuration Protocol (DHCP) for IPv6 relay service on the interface.

SUMMARY STEPS

1.    configure

2.    dhcp ipv6

3.    interface type interface-path-id relay

4.    destination ipv6-address

5.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv6


Example:

RP/0/0/CPU0:router(config) # dhcp ipv6
RP/0/0/CPU0:router(config-dhcpv6)#
 

Enables DHCP for IPv6 and enters the DHCP IPv6 configuration mode.

 
Step 3 interface type interface-path-id relay


Example:

RP/0/0/CPU0:router(config-dhcpv6) # interface tenGigE 0/5/0/0 relay
 

Specifies an interface type and interface-path-id, places the router in interface configuration mode, and enables DHCPv6 relay service on the interface.

 
Step 4 destination ipv6-address


Example:

RP/0/0/CPU0:router(config-dhcpv6-if) # destination 10:10::10
 

Specifies a destination address to which client packets are forwarded.

When relay service is enabled on an interface, a DHCP for IPv6 message received on that interface is forwarded to all configured relay destinations. The incoming DHCP for IPv6 message may have come from a client on that interface, or it may have been relayed by another relay agent.

 
Step 5 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Enabling DHCP Relay Agent on an Interface

This task describes how to enable the Cisco IOS XR DHCP relay agent on an interface.


Note

On Cisco IOS XR software, the DHCP relay agent is disabled by default.
SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    interface type name relay profile profile-name

4.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config-if)# dhcp ipv4
 

Enters DHCP IPv4 configuration submode.

 
Step 3 interface type name relay profile profile-name


Example: 
RP/0/0/CPU0:router(config-dhcpv4)# interface 
FastEthernet0/0 relay profile client
 

Attaches a relay profile to an interface.

 
Step 4 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Disabling DHCP Relay on an Interface

This task describes how to disable the DHCP relay on an interface by assigning the none profile to the interface.

SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    interface type name none

4.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Enters DHCP IPv4 configuration submode.

 
Step 3 interface type name none


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# interface 
pos 0/1/4/1 none
 

Disables the DHCP relay on the interface.

 
Step 4 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Enabling DHCP Relay on a VRF

This task describes how to enable DHCP relay on a VRF.

SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    vrf vrf-name relay profile profile-name

4.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Enters DHCP IPv4 configuration submode.

 
Step 3 vrf vrf-name relay profile profile-name


Example: 
RP/0/0/CPU0:router(config-dhcpv4)
#vrf default relay profile client
 

Enables DHCP relay on a VRF.

 
Step 4 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Configuring the Relay Agent Information Feature

This task describes how to configure the DHCP relay agent information option processing capabilities.

A DHCP relay agent may receive a message from another DHCP relay agent that already contains relay information. By default, the relay information from the previous relay agent is replaced (using the replace option).

SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    profile profile-name relay

4.    relay information option

5.    relay information check

6.    relay information policy {drop | keep}

7.    relay information option allow-untrusted

8.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Enters DHCP IPv4 configuration mode.

 
Step 3 profile profile-name relay


Example: 
RP/0/0/CPU0:router(config-dhcpv4)# profile client relay
 

Enters DHCP IPv4 profile relay mode.

 
Step 4 relay information option


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# relay information option
 

Enables the system to insert the DHCP relay agent information option (option-82 field) in forwarded BOOTREQUEST messages to a DHCP server.


  • This option is injected by the relay agent while forwarding client-originated DHCP packets to the server. Servers recognizing this option can use the information to implement IP address or other parameter assignment policies. When replying, the DHCP server echoes the option back to the relay agent. The relay agent removes the option before forwarding the reply to the client.

  • The relay agent information is organized as a single DHCP option that contains one or more suboptions. These options contain the information known by the relay agent.

    The supported suboptions are:


    • Remote ID

    • Circuit ID

Note   

This function is disabled by default.
 
Step 5 relay information check


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# relay information check
 

(Optional) Configures DHCP to check that the relay agent information option in forwarded BOOTREPLY messages is valid.


  • By default, DHCP checks that the option-82 field in DHCP reply packets, received from the DHCP server, is valid. If an invalid message is received, the relay agent drops the message. If a valid message is received, the relay agent removes the option-82 field and forwards the packet.

Note   

Use the relay information check command to reenable this functionality if the functionality has been disabled.
 
Step 6 relay information policy {drop | keep}


Example: 
RP/0/0/CPU0:router(config)# dhcp relay information policy drop
 

(Optional) Configures the reforwarding policy for a DHCP relay agent; that is, whether the relay agent will drop or keep the relay information.

 
Step 7 relay information option allow-untrusted


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# relay information check
 

(Optional) Configures the DHCP IPv4 Relay not to discard BOOTPREQUEST packets that have an existing relay information option and the giaddr set to zero.

 
Step 8 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Configuring Relay Agent Giaddr Policy

This task describes how to configure BOOTPREQUEST packets for Dynamic Host Configuration Protocol (DHCP) IPv4 Relay processes, that already contain a nonzero giaddr attribute.

SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    profile profile-name relay

4.    giaddr policy {replace | drop}

5.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Enables the DHCP IPv4 configuration submode.

 
Step 3 profile profile-name relay


Example: 
RP/0/0/CPU0:router(config-dhcpv4)# profile client relay
 

Enables profile relay submode.

 
Step 4 giaddr policy {replace | drop}


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# giaddr policy drop
 

Specifies the giaddr policy.


  • replace—Replaces the existing giaddr value with a value that it generates.

  • drop—Drops the packet that has an existing nonzero giaddr value.


 
Step 5 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Configuring the Broadcast Flag Policy

This task describes how to configure DHCP IPv4 Relay to broadcast BOOTPREPLY packets only if the DHCP IPv4 broadcast flag is set in the DHCP IPv4 header.


Note

By default, the DHCP IPv4 Relay always broadcasts BOOTPREPLY packets.
SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    profile profile-name relay

4.    broadcast-flag policy check

5.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Configures DHCP IPv4 mode.

 
Step 3 profile profile-name relay


Example: 
RP/0/0/CPU0:router(config-dhcpv4)# profile client relay
 

Enables profile relay mode.

 
Step 4 broadcast-flag policy check


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# broadcast-flag policy check
 

Enables checking of the broadcast flag in packets.

 
Step 5 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Information About Configuring DHCP IPv6 Information Pools

A DHCP IPv6 configuration information pool is a named entity that includes information about available configuration parameters and policies that control assignment of the parameters to clients from the pool. A pool is configured independently of the DHCP service and is associated with the DHCP service through the command line interface.

Each configuration pool can contain the following configuration parameters and operational information:


  • Prefix delegation information, which could include a list of available prefixes for a particular client and associated preferred and valid lifetimes

  • Domain name service (DNS) servers—List of IPv6 addresses of DNS servers

  • Domain search list—String containing domain names for DNS resolution

  • SIP server address—List of IPv6 addresses of SIP server

  • SIP server domain list—String containing domain names for SIP server

How to Configure DHCP IPv6 Information Pools

This section contains the following task:

Configuring Cisco IOS XR DHCP IPv6 Information Pool Option

This task describes how to enable support for the DHCP IPv6 information pool option with the name pool1.

SUMMARY STEPS

1.    configure

2.    dhcp ipv6

3.    pool pool-name

4.    Use one of the following commands:

  • end
  • commit

5.    show dhcp ipv6 pool [ pool-name ]


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv6


Example: 
RP/0/0/CPU0:router (config)# dhcp ipv6
 

Enables the DHCP IPv6 configuration mode.

 
Step 3 pool pool-name


Example: 
RP/0/0/CPU0:router (config-dhcp ipv6)# pool pool1
 

Creates a DHCP pool specified by the pool-name argument for the prefix delegation and the other configurations on the interface.

 
Step 4 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 
Step 5 show dhcp ipv6 pool [ pool-name ]


Example: 
RP/0/0/CPU0:router# show dhcp ipv6 pool pool1
 

(Optional) Displays the DHCP IPv6 pool name.

 

Configuration Examples for the DHCP Relay Agent

This section provides the following configuration examples:

DHCP Relay Profile: Example

The following example shows how to configure the Cisco IOS XR relay profile:

dhcp ipv4 
 profile client relay
  helper-address vrf foo 10.10.1.1
 !        
! ...

DHCP Relay on an Interface: Example

The following example shows how to enable the DHCP relay agent on an interface:

dhcp ipv4
 interface gigabitethernet 0/1/1/0 relay profile client
!

DHCP Relay on a VRF: Example

The following example shows how to enable the DHCP relay agent on a VRF:

dhcp ipv4
 vrf default relay profile client
!

Relay Agent Information Option Support: Example

The following example shows how to enable the relay agent and the insertion and removal of the DHCP relay information option:

dhcp ipv4
 profile client relay
relay information 
check
 !
!

Relay Agent Giaddr Policy: Example

The following example shows how to configure relay agent giaddr policy:

dhcp ipv4
 profile client relay
  giaddr policy drop
 !
!

Cisco IOS XR Broadcast Flag Policy: Example

This task describes how to configure DHCP IPv4 Relay to broadcast BOOTPREPLY packets only if the DHCP IPv4 broadcast flag is set in the DHCP IPv4 header.


Note

By default, the DHCP IPv4 Relay always broadcasts BOOTPREPLY packets.
SUMMARY STEPS

1.    configure

2.    dhcp ipv4

3.    profile profile name relay

4.    broadcast-flag policy check

5.    Use one of the following commands:

  • end
  • commit


DETAILED STEPS
  Command or Action Purpose
Step 1 configure


Example: 
RP/0/0/CPU0:router# configure
 

Enters global configuration mode.

 
Step 2 dhcp ipv4


Example: 
RP/0/0/CPU0:router(config)# dhcp ipv4
 

Configures DHCP IPv4 mode.

 
Step 3 profile profile name relay


Example: 
RP/0/0/CPU0:router(config-dhcpv4)# profile client relay
 

Enables profile relay mode.

 
Step 4 broadcast-flag policy check


Example: 
RP/0/0/CPU0:router(config-dhcpv4-relay-profile)# broadcast-flag policy check
 

Enables checking of the broadcast flag in packets.

 
Step 5 Use one of the following commands:
  • end
  • commit


Example: 
RP/0/0/CPU0:router(config)# end

or

RP/0/0/CPU0:router(config)# commit
 

Saves configuration changes.


  • When you issue the end command, the system prompts you to commit changes:

    Uncommitted changes found, commit them
before exiting(yes/no/cancel)? [cancel]:

    • Entering yes saves configuration changes to the running configuration file, exits the configuration session, and returns the router to EXEC mode.

    • Entering no exits the configuration session and returns the router to EXEC mode without committing the configuration changes.

    • Entering cancel leaves the router in the current configuration session without exiting or committing the configuration changes.

  • Use the commit command to save the configuration changes to the running configuration file and remain within the configuration session.

 

Additional References

The following sections provide references related to implementing the Cisco IOS XR DHCP relay agent.

Related Documents

Related Topic

Document Title

Cisco IOS XR

DHCP commands

DHCP Commands module in the Cisco IOS XR IP Addresses and Services Command Reference for the Cisco XR 12000 Series Router

Getting started material

Cisco IOS XR Getting Started Guide for the Cisco XR 12000 Series Router

Information about user groups and task IDs

Configuring AAA Services module in the Cisco IOS XR System Security Configuration Guide for the Cisco XR 12000 Series Router

Standards

Standards

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

 —

MIBs

MIBs

MIBs Link
—

To locate and download MIBs, use the Cisco MIB Locator found at the following URL and choose a platform under the Cisco Access Products menu: http://cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

RFC

Title

RFC 2131

RFC 3315

Dynamic Host Configuration Protocol

Dynamic Host Configuration Protocol for IPv6 (DHCPv6)

Technical Assistance

Description

Link

The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/techsupport