DHCP with Vendor-Specific Options. Aruba M3MK1, 7024, 7240, 620, 7280, 650, ArubaOS 6.5.3.x, 3200
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Chapter 46
DHCP with Vendor-Specific Options
n n
This chapter describes how to configure several DHCP vendor-specific options.
Topics in this chapter include: n
Configuring a Windows-Based DHCP Server on page 1113
Enabling DHCP Relay Agent Information Option (Option-82) on page 1116
Enabling Linux DHCP Servers on page 1118
Configuring a Windows-Based DHCP Server
Configuring a Microsoft Windows-based DHCP server to send option 43 to the DHCP client on an Aruba AP consists of the following two tasks: n n
Configuring Option 60
Configuring Option 43
DHCP servers are a popular way of configuring clients with basic networking information such as an IP address, a default gateway, network mask, DNS server, and so on. Most DHCP servers have the ability to also send a variety of optional information, including the Vendor-Specific Option Code, also called option 43.
When a client or an AP requests for option 43 (Vendor Specific Information), the controller responds with the value configured by administrator in the DHCP pool.
Configuring Option 60
This section describes how to configure the Vendor Class Identifier Code (option 60) on a Microsoft Windowsbased DHCP server.
As mentioned in the overview section, option 60 identifies and associates a DHCP client with a particular vendor. Any DHCP server configured to take action based on a client’s vendor ID should also have this option configured.
Since option 60 is not a predefined option on a Windows DHCP server, you must add it to the option list for the server.
Configuring Option 60 using the Windows DHCP Server
1. On the DHCP server, open the DHCP server administration tool by clicking Start > AdministrativeTools >
DHCP .
2. Find your server and right-click on the scope to be configured under the server name. Select Set
Predefined Options .
3. In the Predefined Options and Values dialog box, click Add.
4. In the Option Type dialog box, enter the following information
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Table 279: Configuring Option 60 using the Windows DHCP
Server
Field
Name
Data Type
Code
Description
Information
Aruba Access Point
String
60
Aruba AP vendor class identifier
5. Click OK to save this information.
6. In the Predefined Options and Values dialog box, make sure 060 Aruba Access Point is selected from the
Option Name drop-down list.
7. In the Value field, enter the following information:
String : ArubaAP
8. Click OK to save this information.
9. Under the server, select the scope you want to configure and expand it. Select Scope Options , then select
Configure Options .
10.In the Scope Options dialog box, scroll down and select 060 Aruba Access Point . Confirm the value is set to ArubaAP and click OK .
11.Confirm that the option 060 Aruba Access Point is listed in the right pane.
Configuring Option 43
Configuring Option 43 returns the IP address of the Aruba master controller to an Aruba DHCP client. This information allows Aruba APs to auto-discover the master controller and obtain their configuration.
Configuring Option 43 using the Windows DHCP Server:
1. On the DHCP server, open the DHCP server administration tool by clicking Start > Administration Tools
> DHCP .
2. Find your server and right-click on the scope to be configured under the server name. Click on the Scope
Options entry and select Configure Options .
3. In the Scope Options dialog box ( Figure 238
), scroll down and select 043 Vendor Specific Info .
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Figure 238 Scope Options Dialog Box.
4. In the Data Entry field, click anywhere in the area under the ASCII heading and enter the following information:
ASCII : Loopback address of the master controller
5. Click the OK to save the configuration.
Option 43 is configured for this DHCP scope. Note that even though you entered the IP address in ASCII text, it displays in binary form.
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Figure 239 DHCP Scope Values
Enabling DHCP Relay Agent Information Option (Option-82)
The DHCP Relay Agent Information option (Option-82) allows the DHCP Relay Agent to insert circuit specific information into a request that is being forwarded to a DHCP server.
The controller, when acting as a DHCP relay agent, inserts information about the AP and SSID through which a client connects to the DHCP request. Many service providers use this mechanism to make access control decisions.
Starting from ArubaOS 6.5.1, Option-82 can be customized to cater to the requirements of any Internet
Service Provider (ISP) using the Aruba controller. To facilitate customization using a XML definition, multiple parameters for Circuit ID and Remote ID options of DHCP Option-82 have been introduced. The XML file is used as the input from the user and is validated against an XSD file in the controller. The format in the XML file is parsed and stored in the DHCP relay which is used to insert Option-82 related values in the DHCP request packets sent from the client to the server.
DHCP Option-82 is supported only for IPv4, and applies only to AP Tunnel and D-Tunnel modes.
DHCP Option-82 on L2 VLAN can now be enabled without the helper address.
Sample XML Format
The following is a sample XML file which specifies DHCP Option-82 circuit and remote IDs.
<?xml version="1.0" encoding="UTF-8"?>
<dhcpopt82>
<circuit_id>
<param>
<type>var</type>
<val>apmac</val>
<delim>-</delim>
</param>
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</circuit_id>
<remote_id>
<param>
<type>var</type>
<val>cmac</val>
<delim>:</delim>
</param>
</remote_id>
</dhcpopt82>
The table below lists the elements introduced in the param sub-options of the Circuit ID and Remote ID fields:
XML File Parameters
Parameter
Type
Val
Delim
Description
Listed below are the types available: n var - A DHCP option-82 allowed keyword n n hex - A hexadecimal string with a maximum of 60 characters str - An ASCII string that with a maximum of 60 characters
This field contains either a hexadecimal string or ASCII string limited to 60 characters, if the type is hex or str. If the type is var then one of the following
DHCP option-82 keywords: n n apname - AP name apmac - AP MAC n n n cmac - Client MAC essid - ESSID broadcasted by the AP bssid - BSSID of the AP
The delim option is available only for mac based keywords - apmac, cmac, and bssid. The delim field is used if mac addresses are required to be in ASCII format with octets separated with specified ASCII character in the val part of delim field.
By default the ASCII MAC separated by a delimiter, will be in lower case. If the user wants to use upper case then the respective mac based val keywords should be written in upper case in XML file. For example:
<param>
<type>var</type>
<val>CMAC</val>
<delim>:</delim>
</param>
Configuring XML Based DHCP Option-82 Information
Listed below is the sequence of steps to be followed if a user wants to use XML based DHCP option-82:
1. Upload the XML file containing Option-82 information to flash using the copy command. For example:
(host) #copy scp: 10.20.22.42 piddalagi /home/piddalagi/my_dhcp_option_82.xml flash: my_ dhcp_option_82.xml
Password:**********
Secure File Copy:....
2. In the configuration terminal execute the following command:
#ip dhcp option-82 <xml-file-name-in-flash>
For example:
(host) (config) #ip dhcp option-82 my_dhcp_option_82.xml
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3. After the ip dhcp option-82 <xml-file-name-in-flash> command is executed successfully, in the WLAN interface configuration execute option-82 command to apply option-82 configuration to the DHCP packets that need to be relayed from that interface.
For example:
(host) (config) #interface vlan 25
(host) (config-subif)#option-82
4. Execute the following command if the user wants to remove option-82 configuration:
(host) (config) #no ip dhcp option-82
This command is not successful if there is a WLAN VLAN interface configured with option-82 command. To remove option-82 configuration, go to the respective VLAN interface and execute no option-82 command and then execute the no ip dhcp option-82 command.
Configuring Option-82
You can configure option-82 using the WebUI or the CLI.
In the WebUI
1. Navigate to Configuration > Network > IP > IP Interfaces tab.
2. Click Edit next to the VLAN ID for which you want to configure Option-82.
3. Select the Option-82 check-box to enable option-82.
4. Click Apply .
In the CLI
Execute the following command to configure DHCP Option-82:
(host) (config) #ip dhcp option-82 finalxml.xml
Execute the following command to enable DHCP Option-82 on VLAN with helper address:
(host) (config) #interface vlan 25
(host) (config-subif) #option-82
Execute the following command to enable Option-82 on L2 VLAN:
(host) (config) #vlan 25 option-82
Execute the following command to check if Option-82 is enabled:
(host) #show vlan
VLAN CONFIGURATION
------------------
VLAN
----
1
25
Description
-----------
Default
VLAN0025
Ports
-----
AAA Profile Option-82
-------------------
GE0/0/0-0/1 GE0/0/2-0/5 Pc0-7 N/A
N/A
Disabled
Enabled
Execute the following command to remove Option-82 configuration:
(host) (config) #no ip dhcp option-82
Execute the following command to remove DHCP option-82 configuration on L3 VLAN:
(host) (config) #interface vlan
(host) (config) #no vlan option-82
Enabling Linux DHCP Servers
The following is an example configuration for the Linux dhcpd.conf file. After you enter the configuration, you must restart the DHCP service.
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option serverip code 43 = ip-address; class "vendor-class" {
match option vendor-class-identifier;
}
.
.
.
subnet 10.200.10.0 netmask 255.255.255.0 {
default-lease-time 200;
max-lease-time 200;
option subnet-mask 255.255.255.0;
option routers 10.200.10.1;
option domain-name-servers 10.4.0.12;
option domain-name "vlan10.aa.mycorpnetworks.com";
subclass "vendor-class" "ArubaAP" {
option vendor-class-identifier "ArubaAP";
#
# option serverip <loopback-IP-address-of-master-controller>
#
option serverip 10.200.10.10;
}
range 10.200.10.200 10.200.10.252;
}
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