Technical Documentation

Configuring the Extended DHCP Agent (NSM Procedure)

See the following sections for details on configuring the extended Dynamic Host Configuration Protocol agent.

Configuring Authentication Support for the DHCP Relay Agent (NSM Procedure)

You can configure the parameters the router sends to the external Authentication, Authorization, and Accounting server. A group configuration takes precedence over a global DHCP relay or DHCP local server configuration.

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Forwarding Options > DHCP Relay.
  4. Select Authentication.
  5. Add or modify Authentication settings as specified in Table 1.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 1: Authentication Configuration Details

Task Your Action

Configure the password.
  1. Expand Authentication.
  2. In the Comment box, enter the comment for authentication.
  3. In the Password box, enter the password to be sent to the external AAA authentication server for subscriber authentication.

Configure the username.
  1. Click Username Include next to Authentication.
  2. In the Comment box, enter the comment.
  3. In the Delimiter box, enter the character used as the delimiter between the concatenated components of the username.

    You cannot use the semicolon (;) as a delimiter.

  4. In the Domain Name box, enter the domain name that is concatenated with the username during the subscriber authentication process.
  5. In the User prefix box, enter the user prefix concatenated with the username during the subscriber authentication process.
    • Select Mac Address check box if the MAC address from the client PDU be concatenated with the username during the subscriber authentication process.
    • Select Logical System Name check box if the logical system name be concatenated with the username during the subscriber authentication process.
    • Select Routing Instance Name check box if the routing instance name be concatenated with the username during the subscriber authentication process.
    • Select Option 60 check box if the payload of the Option 60 (Vendor Class Identifier) from the client PDU be concatenated with the username during the subscriber authentication process.
    • Select Circuit Type check box if the circuit type be concatenated with the username during the subscriber authentication process.
  6. Click Option 82 next to Username Include.
  7. Select the Circuit-id or remote id check box to select the string for the agent circuit ID suboption.

Configuring Group (NSM Procedure)

You can specify the name of a group of interfaces that have a common DHCP relay agent configuration. A group must contain at least one interface.

To configure group of interfaces:

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Forwarding Options > DHCP Relay.
  4. Select Group.
  5. Add or modify settings as specified in Table 2.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 2: Group Configuration Details

Task

Your Action

Configuring authentication support for the DHCP relay agent.

See Configuring Authentication Support for the DHCP Relay Agent (NSM Procedure)

Specify one or more interfaces, or a range of interfaces, that are within a specified group on which the DHCP local server is enabled.

  1. Click Add new entry next to Group.
  2. Expand Group.
  3. Click Interface next to group.
  4. Click Add new entry next to Interface.
  5. From the Name list, select the name of the interface.
  6. In the Comment box, enter the comment.
  7. From the Upto list, select the upper end of the range of interfaces.
  8. Select the Exclude check box to exclude an interface or a range of interfaces from the group.

Overriding the default configuration settings for the extended DHCP relay agent.

SeeOverriding the Default Configuration Settings for the Extended DHCP Relay Agent (NSM Procedure).

Configuring relay option 60 Information for forwarding client traffic to specific DHCP servers.

SeeConfiguring Relay Option 60 Information for Forwarding Client Traffic to Specific DHCP Servers (NSM Procedure).

Configuring relay option 82 for a DHCP server.

See Configuring Relay Option 82 for a DHCP Server (NSM Procedure).

Overriding the Default Configuration Settings for the Extended DHCP Relay Agent (NSM Procedure)

You can override the default configuration settings for the extended DHCP relay agent. Specifying the overrides statement with no subordinate statements removes all DHCP relay agent overrides at that hierarchy level.

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, select Forwarding Options > DHCP Relay.
  4. Select Overrides.
  5. Add or modify settings as specified in Table 3.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 3: Overrides Configuration Details

Option Function Your Action

Comment

Specifies the comment for the override.

In the Comment box, enter the comment.

always-write-giaddr

Overwrites the gateway IP address (giaddr) of every DHCP packet with the gateway IP address of the DHCP relay agent before forwarding the packet to the DHCP server.

Select the Always Write Giaddr check box.

always-write-option-82

Overrides the DHCP relay agent information option (option 82) in DHCP packets destined for a DHCP server.

Select the Always Write Option 82 check box.

layer2-unicast-replies

Overrides the setting of the broadcast bit in DHCP request packets and instead use the Layer 2 unicast transmission method to transmit DHCP Offer reply packets and DHCP ACK reply packets from the DHCP server to DHCP clients during the discovery process.

Select the Layer2 Unicast Replies check box.

trust-option-82

Enables processing of DHCP client packets that have a gateway IP address (giaddr) of 0 (zero) and contain option 82 information.

Select the Trust Option 82 check box.

disable-relay

Disables DHCP relay on specific interfaces in a group.

Select the disable-relay check box.

Interface client limit

Specifies the interface client limit.

From the Interface Client Limit list, select the interface client limit.

No Arp

Disable Address Resolution Protocol entry for this client.

Select the No Arp check box to drop the unwanted ARP requests.

Configuring Relay Option 60 Information for Forwarding Client Traffic to Specific DHCP Servers (NSM Procedure)

You can configure the extended DHCP relay agent to use the DHCP vendor class identifier option (option 60) in DHCP client packets to forward client traffic to specific DHCP servers or to drop selected DHCP client packets. This feature is useful in network environments where DHCP clients access services provided by multiple vendors and DHCP servers.

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the tree, expand Forwarding Options > DHCP Relay.
  4. Select Relay Option 60.
  5. Add or modify settings as specified in Table 4.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 4: Relay Option 60 Configuration Details

Task

Your Action

Configure the match criteria when you use the DHCP vendor class identifier option (option 60) in DHCP client packets to forward client traffic to specific DHCP servers.

  1. In the Comment box, enter the comment for the relay option 60.
  2. Click Vendor Option next to Relay Option 60.
  3. In the Comment box, enter the comment for Vendor Option.
  4. Click Default Relay Server Group next to Vendor Option and select the name of the default DHCP relay server group.
    • Select Drop to drop DHCP client packets that contain an option 60 string that matches the ASCII or hexadecimal match string and match criteria.

Configure the match string using the Equals and Starts With options.

  1. Expand Equals and Starts With next to Default Relay Server Group.
  2. Click Add new entry next to Equals and Starts With.
  3. Expand ascii.
  4. In the name box, enter the ASCII match string of 1 through 255 alphanumeric characters.
  5. Click Relay Server Group next to ascii.
  6. In the Comment box, enter the comment for the ASCII.
  7. Select the name of the extended DHCP local server group and enter the group name in the box.
    • Select Drop to drop DHCP client packets that contain an option 60 string that matches the ASCII or hexadecimal match string and match criteria.
  8. Click Hexadecimal next to ascii.
  9. Click Add new entry next to Hexadecimal.
  10. Expand hexadecimal.
  11. In the Name box, enter the Hexadecimal match string.
  12. Click Relay Server Group next to ascii.
  13. In the Comment box, enter the comment for the ASCII.
  14. Select the name of the extended DHCP local server group and enter the group name in the box.
    • Select Drop to drop DHCP client packets that contain an option 60 string that matches the ASCII or hexadecimal match string and match criteria.

Configuring Relay Option 82 for a DHCP Server (NSM Procedure)

You can enable or disable the insertion of the DHCP relay agent information option (option 82) in DHCP packets destined for a DHCP server.

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Forwarding Options > DHCP Relay.
  4. Select Relay Option 82.
  5. Add or modify settings as specified in Table 5.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 5: Relay option 82 Configuration Details

Task

Your Action

Enable or disable the insertion of the DHCP relay agent information option (option 82) in DHCP packets destined for a DHCP server.

  1. Expand Relay Option 82.
  2. In the Comment box, enter the comment for the relay option 82.
  3. Click Circuit Id next to Relay Option 82.
  4. In the Comment box, enter the comment.
  5. Click Prefix next to Circuit Id.
  6. In the Comment box, enter the comment.
  7. Select the prefix to be added to the base option 82 agent circuit ID information in DHCP packets destined for a DHCP server. The prefix can consist of any combination of the hostname, logical system name, and routing instance name.

Specifying the Name of a Group of DHCP Server Addresses for Use by the Extended DHCP Relay Agent (NSM Procedure)

You can specify the name of a group of DHCP server addresses for use by the extended DHCP relay agent.

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Forwarding Options > DHCP Relay.
  4. Select Server Group.
  5. Add or modify settings as specified in Table 6.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 6: Sever Group Configuration Details

Task Your Action

Specify the name of a group of DHCP server addresses for use by the extended DHCP relay agent.

  1. Expand Server Group.
  2. In the Comment box, enter the comment for the server group.
  3. Click Server Group next to Server Group.
  4. Click Add new entry next to Server Group.
  5. Expand Server-Group.
  6. In the Name box, enter the name of the group of DHCP server addresses.
  7. In the Comment box, enter the comment for the server group.
  8. Click Address next to Server-Group.
  9. Click Add new entry next to Address.
  10. In the Name box, enter the IP address of the DHCP server belonging to this named server group. You can configure a maximum of five IP addresses per named server group.

Configuring Operations for Extended DHCP Relay Agent Processes (NSM Procedure)

You can configure tracing operations for extended DHCP relay agent processes.

To configure tracing operations for DHCP relay agent in NSM:

  1. In the NSM navigation tree, select Device Manager > Devices.
  2. Click the Device Tree tab, and then double-click the device to select it.
  3. Click the Configuration tab. In the configuration tree, expand Forwarding Options > DHCP Relay.
  4. Select Traceoptions.
  5. Add or modify settings as specified in Table 7.
  6. Click one:
    • OK—Saves the changes.
    • Cancel—Cancels the modifications.

Table 7: DHCP Relay Traceoptions Configuration Details

Task Your Action

Configure tracing operations for extended DHCP relay agent processes.

  1. In the Comment box, enter the comment for the traceoptions.
  2. Select the No Remote Trace check box to disable remote tracing globally or for a specific tracing operation.

Specify the name of the file to receive the output of the tracing operation and specifies the maximum number of trace files.

  1. Click File next to Traceoptions.
  2. In the Comment box, enter the comment for the file.
  3. In the Filename box, enter the name of the file to receive the output of the tracing operation.
  4. In the Size box, enter the maximum size of each trace file, in kilobytes (KB), megabytes (MB), or gigabytes (GB).
  5. From the Files list, select the maximum number of trace files.

    Range: 2 through 1000.

  6. Select one of the following:
    • world-readable—To enable unrestricted file access
    • no-world-readable—To restrict file access to owner
  7. In the Match box, enter the regular expression.

Specify the tracing operation to perform. To specify more than one tracing operation, include multiple flag statements.

  1. Click Flag next to Traceoptions.
  2. Click Add new entry next to Flag.
  3. From the Name list, select the flag.
  4. In the Comment box, enter the comment for the flag.

Published: 2009-08-23