- DHCP Overview
- Configuring the Cisco IOS DHCP Server
- DHCP Server MIB
- Configuring the DHCP Server On-Demand Address Pool Manager
- DHCP Server RADIUS Proxy
- Configuring the Cisco IOS DHCP Relay Agent
- Configuring the Cisco IOS DHCP Client
- DHCP Option 82 Configurable Circuit ID and Remote ID
- Configuring DHCP Services for Accounting and Security
- Configuring DHCP Enhancements for Edge Session Management
- ISSU and SSO--DHCP High Availability Features
- DHCP Option 82 Support for Routed Bridge Encapsulation
- DHCPv6 Bulk-Lease Query
- DHCPv6 Relay and Server - MPLS VPN Support
- DHCPv6 Relay Source Configuration
- IPv6 Access Services: DHCPv6 Relay Agent
- DHCPv6 Server Stateless Autoconfiguration
- IPv6 Access Services: Stateless DHCPv6
- DHCPv6 Repackaging
- IPv6 Access Services: DHCPv6 Prefix Delegation
- DHCPv6 Guard
- Finding Feature Information
- Prerequisites for DHCP Option 82 Support for Routed Bridge Encapsulation
- Information About DHCP Option 82 Support for Routed Bridge Encapsulation
DHCP Option 82 Support for Routed Bridge Encapsulation
The DHCP Option 82 Support for Routed Bridge Encapsulation feature allows service providers to create a policy on a DHCP server to determine the number of IP addresses (number of bridging users) to be assigned to a particular ATM virtual path identifier/virtual channel identifier (VPI/VCI) port.
- Finding Feature Information
- Prerequisites for DHCP Option 82 Support for Routed Bridge Encapsulation
- Information About DHCP Option 82 Support for Routed Bridge Encapsulation
- How to Configure DHCP Option 82 Support for Routed Bridge Encapsulation
- Configuration Examples for DHCP Option 82 Support for Routed Bridge Encapsulation
- Additional References
- Feature Information for DHCP Option 82 Support for Routed Bridge Encapsulation
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 at the end of this module.
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.
Prerequisites for DHCP Option 82 Support for Routed Bridge Encapsulation
Configure the DHCP Option 82 Support feature on the DHCP relay agent using the ip dhcp relay information option command before configuring the DHCP Option 82 Support for Routed Bridge Encapsulation feature.
Information About DHCP Option 82 Support for Routed Bridge Encapsulation
DHCP Option 82 for Routed Bridge Encapsulation--Overview
The DHCP relay agent information option (option 82) enables a DHCP relay agent to include information about itself when forwarding client-originated DHCP packets to a DHCP server. The DHCP server can use this information to implement IP address or other parameter-assignment policies.
The DHCP Option 82 Support for Routed Bridge Encapsulation feature provides support for the DHCP relay agent information option when ATM routed bridge encapsulation (RBE) is used. The figure below shows a typical network topology in which ATM RBE and DHCP are used. The aggregation router that is using ATM RBE is also serving as the DHCP relay agent.
| Figure 1 | Network Topology Using ATM RBE and DHCP |
The DHCP Option 82 Support for Routed Bridge Encapsulation feature communicates information to the DHCP server using a suboption of the DHCP relay agent information option called agent remote ID. The information sent in the agent remote ID includes an IP address identifying the relay agent and information about the ATM interface and the permanent virtual circuit (PVC) over which the DHCP request came in. The DHCP server can use this information to make IP address assignments and security policy decisions.
The figure below shows the format of the agent remote ID suboption.
| Figure 2 | Format of the Agent Remote ID Suboption |
The table below describes the agent remote ID suboption fields displayed in the figure above.
| Table 1 | Agent Remote ID Suboption Field Descriptions |
| Field |
Description |
|---|---|
| Port type |
Port type. The value 0x01 indicates RBE (1 byte). |
| Version |
Option 82 version. The value 0x01 specifies the RBE version of option 82 (1 byte). |
| Reserved |
Reserved (2 bytes). |
| NAS IP address |
IP address of one of the interfaces on the DHCP relay agent. The rbe nasip command can be used to specify which IP address will be used (4 bytes). |
| NAS port |
RBE-enabled virtual circuit on which the DHCP request has come in. See the figure below for the format of this field (4 bytes). |
The figure below shows the format of the network access server (NAS) port field in the agent remote ID suboption.
| Figure 3 | Format of the NAS Port Field |
The figure below shows the format of the interface field. If there is no module, the value of the module bit is 0.
| Figure 4 | Format of the Interface Field |
Benefits
The DHCP Option 82 Support for Routed Bridge Encapsulation feature enables the service providers to use DHCP to assign IP addresses and DHCP option 82 to implement security and IP address assignment policies.
How to Configure DHCP Option 82 Support for Routed Bridge Encapsulation
Configuring the DHCP Option 82 Support for Routed Bridge Encapsulation Feature
Perform this task to configure the DHCP Option 82 Support for Routed Bridge Encapsulation feature.
DETAILED STEPS
Configuration Examples for DHCP Option 82 Support for Routed Bridge Encapsulation
Example DHCP Option 82 Support for Routed Bridge Encapsulation
The following example shows how to enable DHCP option 82 support on the DHCP relay agent using the ip dhcp relay information option command. The rbe nasip command configures the router to forward the IP address for Loopback0 to the DHCP server.
ip dhcp-server 172.16.1.2 ! ip dhcp relay information option ! interface Loopback0 ip address 10.1.1.129 255.255.255.192 ! interface ATM 4/0 no ip address ! interface ATM 4/0.1 point-to-point ip unnumbered Loopback0 ip helper-address 172.16.1.2 atm route-bridged ip pvc 88/800 encapsulation aal5snap ! ! interface Ethernet 5/1 ip address 172.16.1.1 255.255.0.0 ! router eigrp 100 network 10.1.0.0 network 172.16.0.0 ! rbe nasip Loopback 0
For this configuration example, the value (in hexadecimal) of the agent remote ID suboption is 010100000B01018140580320. The table below shows the value of each field within the agent remote ID suboption.
| Table 2 | Agent Remote ID Suboption Field Values |
| Agent Remote ID Suboption Field |
Value |
|---|---|
| Port type |
0x01 |
| Version |
0x01 |
| Reserved |
Undefined |
| NAS IP address |
0x0B010181 (hexadecimal value of 11.1.1.129) |
| NAS port |
Additional References
Related Documents
| Related Topic |
Document Title |
|---|---|
| Cisco IOS commands |
|
| DHCP Commands |
Cisco IOS IP Addressing Services Command Reference |
| DHCP Configuration |
Cisco IOS IP Addressing Services Configuration Guide |
| Cisco IOS Wide-Area Networking Commands |
Cisco IOS Wide-Area Networking Command Reference |
| Cisco IOS Wide-Area Networking Configuration |
Cisco IOS Wide-Area Networking Configuration Guide |
Standards
| Standard |
Title |
|---|---|
| No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIBs
| MIB |
MIBs Link |
|---|---|
| No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. |
To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
| RFC |
Title |
|---|---|
| No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
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 Option 82 Support for Routed Bridge Encapsulation
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.
| Table 3 | Feature Information for DHCP Option 82 Support for Routed Bridge Encapsulation |
| Feature Name |
Releases |
Feature Information |
|---|---|---|
| DHCP Option 82 Support for Routed Bridge Encapsulation |
15.1(1)S 12.2(28)SB 12.2(2)T |
The DHCP Option 82 Support for Routed Bridge Encapsulation feature allows service providers to create a policy on a DHCP server to determine the number of IP addresses (number of bridging users) to be assigned to a particular ATM VPI/VCI port. The following command was introduced or modified: rbe nasip. |
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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