Configuring DHCP Option 43
Note
DHCP Option 43 is limited to one access point type per DHCP pool. You must configure a separate DHCP
pool for each access point type.
The Cisco CW9164I access point uses the type-length-value (TLV) format for DHCP Option 43. DHCP
servers must be programmed to return the option based on the access point DHCP Vendor Class Identifier
(VCI) string (DHCP Option 43). The VCI string for the Cisco CW9164I access point is:
Cisco AP CW9164I
The following is the format of the TLV block:
• Type: 0xf1 (decimal 241)
• Length: Number of controller IP addresses x 4
• Value: IP addresses of the wireless controller management interfaces listed sequentially in Hex code.
To configure DHCP Option 43 in the embedded Cisco IOS DHCP server, follow these steps:
Procedure
Step 1
Enter the configuration mode
Step 2
Create the DHCP pool, including the necessary parameters, such as default router and name server. A DHCP
scope example is as follows:
ip dhcp pool <pool name>
network <IP Network> <Netmask>
default-router <Default router>
dns-server <DNS Server>
Here:
<pool name> is the name of the DHCP pool, such as AP9164I.
<IP Network> is the network IP address where the controller resides, such as 10.0.15.1.
<Netmask> is the subnet mask, such as 255.255.255.0.
<Default router> is the IP address of the default router, such as 10.0.0.1.
<DNS Server> is the IP address of the DNS server, such as 10.0.10.2.
Step 3
Add the Option 43 line using the following syntax:
option 43 hex <hex string>
The hex string is assembled by concatenating the following TLV values:
Type + Length + Value
For example, if there are two controllers with management interface IP addresses, 10.126.126.2 and
10.127.127.2, the type is f1(hex), the length is 2 * 4 = 8 = 08 (hex), and the IP addresses translate to 0a7e7e02
Cisco Catalyst Wireless 9164I Series Wi-Fi 6E Access Point Hardware Installation Guide
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Troubleshooting