Background
When the AP and AC are in the same network segment, the AP will actively send broadcast messages and can directly find the AC in the network segment. When the AP and AC are in different network segments, broadcast packets cannot be propagated across network segments. Only by specifying the AC IP address on the AP can the AP find the AC and go online.
If there are only a few APs, you can use a simple and manual way to specify AC, which is to log in to the AP and type in the command to specify AC on the AP. If there are many APs, manually specifying AC methods, operation and copying are large, it will not be applicable. You have to use batch-specifying AC methods, that is, specifying the AC IP address through the DHCP option 43 field to enable batch-based AP online.
option 43
option 43 is a custom option to represent the AC IP address. The AP obtains the AC IP address information through the option 43 field of DHCP, and then sends unicast messages to find the corresponding AC, so as to realize the zero configuration of the AP. The APs mentioned here all refer to FIT APs.
has prerequisites for using option 43, that is, the AP and DHCP server are accessible to ensure that the AP can interact with the DHCP server normally; the AP and AC routes are accessible to ensure that the AP can interact with the AC messages.
option 43 format
option 43 value, there are three notations: hexadecimal, -digit and ASCII code. For example, when the AC IP address is 192.168.100.1, when it is represented in hexadecimal, the value is c0a86401; when it is represented in decimal, the value is 192.168.100.1; when it is represented in ASCII, the value is 3139322e3136382e3130302e31, where "." corresponds to 2e. The most common format is hexadecimal values, which are also the best compatibility.
sometimes also uses it in conjunction with the option 60 field, which represents the name of the device manufacturer.
Huawei configuration option 43
Taking Huawei devices as an example, configure option 43, and the AC IP address is 192.168.100.1.
dhcp server option 43 hex 0104c0a86401
Where, 01 represents type 1, Huawei has three types, namely hexadecimal, decimal, and ASCII codes. 04 represents the field length, each IP address occupies 4 bytes, and the calculation formula is to multiply 4 the number of IP addresses. c0a86401 is a hexadecimal number of 192.168.100.1.
Hua San configuration option 43
Taking Hua San device as an example, configure option 43, and the AC IP address is 192.168.100.1.
[AC]dhcp server ip-pool vlan10
[AC-dhcp-pool-vlan100] network 192.168.10.0 mask 255.255.255.0
[AC-dhcp-pool-vlan100] gateway-list 192.168.10.1
[AC-dhcp-pool-vlan100] option 43 hex 80070000 01 C0A86401
where 80 represents a type and is a fixed value. 07 indicates the length of the contents afterwards, which also means that there are 7 hexadecimal numbers and an AC IP address afterwards. If the value is 0B, it means that there are 11 hexadecimal numbers after it, that is, two AC IP addresses. 0000 represents service type , which is a fixed value. 01 indicates the number of IP addresses afterwards. c0a86401 is a hexadecimal number of 192.168.100.1.
cisco configuration option 43
Taking the cisco device as an example, configure option 43, and the AC IP address is 192.168.100.1.
Cisco(config)#ip dhcp pool AP
Cisco(dhcp-config)#network 192.168.10.0 /24
Cisco(dhcp-config)#default-route 102.168.10.1
Cisco(dhcp-config)#option 43 hex f1040c0a86401
where f1 represents a type and is a fixed value. 04 represents the length of the contents afterwards, that is, 4 hexadecimal numbers, and has an AC IP address. c0a86401 is a hexadecimal number of 192.168.100.1.
Linux ISC DHCP server configuration option 43
Taking Linux ISC DHCP server as an example, configure option 43 and option 60, Cisco AC IP address is 192.168.247.5, and Huawei AC IP address is 192.168.247.5.
configuration file path
/etc/dhcp/dhcpd.conf
#
ddns-update-style interim;
option space Cisco_LWAPP_AP;
option Cisco_LWAPP_AP.server-address code 241 = array of ip-address;
option space Huawei-AP6050DN;
option Huawei-AP6050DN.server-address code 1 = array of ip-address;
subnet 192.3.1.0 netmask 255.255.255.0 {
authoritative;
range 192.3.1.100 192.3.1.254;
option subnet-mask 255.255.255.0;
option broadcast-address 192.3.1.255;
option routers 192.3.1.1;
option domain-name "huawei.com";
option domain-name-servers 192.168.247.2, 192.168.247.3;
default-lease-time 300;
class "Cisco-AP-c1700" {
match if option vendor-class-identifier = "Cisco-AP-c1700";
option vendor-class-identifier "Cisco-AP-c1700";
vendor-option-space Cisco_LWAPP_AP;
option Cisco_LWAPP_AP.server-address 192.168.247.5; }
class "huawei AP" {
match if option vendor-class-identifier = "huawei AP";
option vendor-class-identifier "huawei AP";
vendor-option-space Huawei-AP6050DN;
option Huawei-AP6050DN.server-address 192.168.247.55; }
subnet 192.168.1.0 netmask 255.255.255.0 {
}
#
Windows DHCP server configuration option 43
Taking the Windows DHCP server as an example, configure option 43, and the AC IP address is 192.168.22.1.
Enter the Window DHCP server configuration interface
Write the hexadecimal number in " binary "
where, 03 represents type 3, 0C represents the length of the following content, which means that there are 12 hexadecimal numbers afterwards, treat 192.168.22.1 as the string and convert it into hexadecimal. 31 39 32 2E 31 36 38 2E 32 32 2E 31 is the ASCII code corresponding to IP address 192.168.22.1. 0-9 corresponds to 30-39, and "." corresponds to 2E, respectively. "ASCII" does not need to be filled in and is automatically generated based on the content of "binary".
Infoblox DHCP server configuration option 43
Taking Infoblox server as an example, configure option 43, and the AC IP address is 10.6.2.1.
IP address 10.6.2.1 is converted to the format of 03:08:31:30:2e:36:2e:32:2e:31. The two characters need to be separated by colon .
where, 03 represents type 3, 08 represents the length of the content afterwards, which means that there are 8 hexadecimal numbers afterwards, and 10.6.2.1 is regarded as a string and converted into hexadecimal. 31:30:2e:36:2e:32:2e:31 is the ASCII code corresponding to IP address 10.6.2.1.
Last
The above option 43 configuration is for example only. When using it, you need to check the product descriptions of the DHCP server and AP separately, and use the format or type that can match to ensure that the AP can recognize the content of option 43. For example: When configuring aruba ap, you can directly fill in the AC IP address on Infoblox, such as: 192.168.100.1, without converting the format.
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