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

Relay agent Option 82 per Ethernet Flow Points

Updated: August 12, 2026

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This topic describes DHCP relay agent Option 82 support on the Cisco 8000 Series Router, which lets you insert Circuit ID and Remote ID suboptions per Ethernet Flow Point (EFP) or per ingress Layer 2 interface into forwarded DHCP packets.

In forwarded BOOTREQUEST messages to a DHCP server, you can configure the relay agent to insert Option 82 suboptions in the DHCP packet. The Option 82 suboptions available for configuration are Circuit ID and Remote ID. When a DHCP relay profile is attached to a Bridge Virtual Interface (BVI), you can assign the Option 82 Circuit ID and Remote ID per EFP or per ingress Layer 2 interface. The relay agent then sends the DHCP packet to the server with the included Option 82 Circuit ID or Remote ID. DHCP relay agent Option 82 provides security when DHCP is used to allocate network addresses. Thus, you can enable the DHCP relay agent to prevent DHCP client requests from untrusted sources.

Table 1. Feature History Table
Feature Name	Release	Description
Option 82 support in DHCP packets	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.
Option 82 support in DHCP packets	Release 26.2.1	Introduced in this release on: Fixed Systems (8010 [ASIC: A100]) This feature support is supported on: 8011-32Y8L2H2FH 8011-12G12X4Y-A/D 8011-4G24Y4H-I
Option 82 support in DHCP packets	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.
Option 82 support in DHCP packets	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
Option 82 support in DHCP packets	Release 25.1.1	Introduced in this release on: Modular Systems (8800 [LC ASIC: P100]) (select variants only) By utilizing DHCP relay agent Option 82 functionality, you can now enhance the network security by ensuring that DHCP allocates network addresses only to trusted sources. This reduces the risk of unauthorized devices gaining network access. You can achieve this by assigning Option 82 Circuit ID and Remote ID per Ethernet Flow Points (EFP) or per ingress Layer 2 interface in the DHCP packet. This feature is supported on: 88-LC1-52Y8H-EM 88-LC1-12TH24FH-E

Benefits of configuring relay agent Option 82

Configuring relay agent Option 82 provides these benefits:

Option 82 allows for better tracking of where DHCP requests originate, making it easier to manage and troubleshoot network connections.
By identifying the origin of DHCP requests, network resources such as IP addresses can be allocated more efficiently and appropriately based on the source location.

Configure relay agent Option 82 per Ethernet Flow Points

Procedure

Configure DHCP for IPv4 and enter the DHCPv4 configuration submode.
Example:
```
Router# configure
Router(config)# dhcp ipv4
```

Enable the DHCP relay profile.

Example:

Router(config-dhcpv4)# profile bvi1_profile relay

Configure VRF addresses for forwarding UDP broadcasts, including DHCP.
Example:
```
Router(config-dhcpv4-relay-profile)# helper-address 192.0.2.1
```
Insert the DHCP relay agent information option (option-82 field) in forwarded BOOTREQUEST messages to a DHCP server.
Example:
```
Router(config-dhcpv4-relay-profile)# relay information option
Router(config-dhcpv4-relay-profile)# exit
```
Enable DHCP for IPv4 on a BVI interface and attach the profile as the relay profile for the BVI interface.
Example:
```
Router(config-dhcpv4)# interface BVI1 relay profile bvi1_profile
```
Enable the DHCP relay agent to add the Option 82 Circuit ID field in ASCII or hex format per EFP to the DHCP packet.
Example:
```
Router(config-dhcpv4)# interface Bundle-Ether50.103 relay information option circuit-id format-type ascii 110
```

Enable the DHCP relay agent to add the Option 82 Remote ID field in ASCII or hex format per EFP to the DHCP packet.

Example:

Router(config-dhcpv4)# interface Bundle-Ether50.103 relay information option remote-id format-type ascii 110
Router(config-dhcpv4)# commit

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