IP Addresses and Services Configuration Guide for Cisco 8000 Series Routers, IOS XR Releases

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IP Addresses and Services Configuration Guide for Cisco 8000 Series Routers, IOS XR Releases

DHCP client

Updated: August 12, 2026

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This topic describes the DHCP client functionality on the Cisco 8000 Series Router, which allows router interfaces to dynamically acquire IP address and server information.

The DHCP client functionality

allows router interfaces to dynamically acquire the IPv4 or IPv6 address and DHCPv4 or DHCPv6 server information, and
forwards responses to the correct Layer 2 address, ensuring that each device receives the appropriate configuration information.

Table 1. Feature History Table
Feature Name	Release	Description
Support for DHCP client	Release 26.3.1	Introduced in this release on: Modular Systems (8800 [LC ASIC: K100])(select variants only) This feature is supported on Cisco 88-LC1-48Y8F-EM line cards.
Support for DHCP client	Release 26.2.1	Introduced in this release on: Fixed Systems (8010 [ASIC: A100]) This feature support is now supported on: 8011-32Y8L2H2FH 8011-12G12X4Y-A/D 8011-4G24Y4H-I
Support for DHCP client	Release 26.1.1	Introduced in this release on: Centralized Systems (8400 [ASIC: K100])(select variants only) This feature is supported on Cisco 8404-SYS-D router.
Support for DHCP client	Release 25.4.1	Introduced in this release on: Fixed Systems (8700 [ASIC: K100])(select variants only) This feature is supported on: 8712-MOD-M 8711-48Z-M
Support for DHCP client	Release 25.2.1	Introduced in this release on: Fixed Systems (8200 [ASIC: P100], 8700 [ASIC: P100])(select variants only); Modular Systems (8800 [LC ASIC: P100])(select variants only) *This feature is supported on: 8212-48FH-M 8711-32FH-M 88-LC1-36EH
Support for DHCP client	Release 25.1.1	Introduced in this release on: Modular Systems (8800 [LC ASIC: P100]) (select variants only) This release introduces the Dynamic Host Configuration Protocol (DHCP) client functionality. DHCP client is crucial for efficiently managing IP address allocation in a network. It enables router interfaces to dynamically obtain server information for DHCPv4 or DHCPv6, and ensures that the configuration responses are sent to the appropriate Layer 2 addresses. This process ensures that each device on the network receives the correct configuration data. This feature is supported on: 88-LC1-52Y8H-EM 88-LC1-12TH24FH-E

DHCP can allocate IP addresses only for a specified duration, known as the lease period. If a client needs to retain an IP address for a longer period beyond the lease period, the lease period must be renewed before the IP address expires. The client renews the lease period based on the server's configuration by unicasting a REQUEST message to the server's IP address. Upon receiving the REQUEST, the server responds with an ACK message, extending the client's lease period as specified in the ACK.

Configuration guideline for DHCP clients

Either DHCPv4, DHCPv6, static IPv4, or static IPv6 can be configured on an interface.

Enable DHCP client on an interface

The DHCPv4 or DHCPv6 client can be enabled at an interface level. The DHCP component receives a notification when DHCPv4 or DHCPv6 is enabled or disabled on an interface.

Router# configure
Router(config)# interface bvi
Router(config)# interface bvi_interface_name  ipv6 address dhcp

You can configure DHCPv6 client on BVI interfaces. You can configure different DHCPv6 client options to differentiate between clients as required. The different DHCPv6 client options are also configured to differentiate how a DHCPv6 client communicates with a DHCPv6 server. The different DHCPv6 client options that you can configure are:

DUID: If the DUID DHCPv6 client option is configured on an interface, DHCPv6 client communicates with the DHCPv6 server through the link layer address.
Rapid Commit: If the Rapid Commit DHCPv6 client option is configured on an interface, DHCPv6 client can obtain configuration parameters from the DHCPv6 server through a rapid two-step exchange (solicit and reply) instead of the default four-step exchange (solicit, advertise, request, and reply).
DHCP Options: The various other DHCPv6 options that can be configured on a DHCPv6 client are:
- Option 15: Option 15 is also known as the User Class option and it is used by a DHCPv6 client to identify the type or category of users or applications it represents.
- Option 16: Option 16 is also known as the Vendor ID option and it is used by a DHCPv6 a client to identify the vendor that manufactured the hardware on which the client is running.
- Option 23: Option 23 is also known as the Domain name Server (DNS) option provides a list of one or more IPv6 addresses of DNS recursive name servers to which a client's DNS resolver can send DNS queries.
- Option 24: Option 24 is also known as the Domain List option and it specifies the domain search list that the client uses to resolve hostnames with the DNS.
DHCP Timers: This option is used to set different timer value for DHCP client configurations. The various DHCP timer options are:
- Release-timeout: It is used to set retransmission timeout value for the initial release message.
- Req-max-rt: It is used to set the maximum retransmission timeout value for the request message.
- Req-timeout: It is used to set the initial request timeout value of the request message.
- Sol-max-delay: It is used to set the maximum delay time of the first solicit message.
- Sol-max-rt: It is used to set the maximum solicit retransmission time.
- Sol-time-out: It is used to set the intial timeout value of the solicit message.

Procedure

Enter the global configuration mode, and then configure a BVI interface.
Example:
```
Router# configure
Router(config)# interface BVI 1
```
Enter the DHCPv6 client mode and commit the configuration.
Example:
```
Router(config)# ipv6 address dhcp
Router(config)# commit
```

To verify the DHCPv6 client mode, use the show dhcp ipv6 client command:

Router# show dhcp ipv6 client
Interface name IPv6 Address State Lease Time Rem
---------------------- -------------- --------------- --------------------
BVI1 2001::1:2/128 BOUND 2591973

What to do next

Associated commands:

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