Configuring SIP Option with Two IP Addresses or Two Domain Names

Configuring SIP server option is pool-specific and will be offered to the clients in the pool as a configuration parameter.

Session Initiation Protocol (SIP) is mostly well known for establishing voice and video calls over the Internet. To initiate such sessions, SIP uses simple request and response messages. For example, the INVITE request message is used to invite a user to begin a session and ACK confirms the user has received the request. The response code 180 (Ringing) means the user is being alerted of the call and 200 (OK) indicates the request was successful. Once a session has been established, BYE is used to end the communication.

To configure SIP server option with two IP Addresses or two Domain Names:

Create a pool and enter the DHCP Pool Configuration mode.
iS5comm(config)# ip dhcp pool <pool number (1-2147483647)>

iS5comm(config)# ip dhcp pool 1

A pool number is entered. The range is from 1 to 2147483647.
Configure SIP server option with two IP addresses.
iS5comm(dhcp-config)# sip-server ip <ip address> [<ip address>]

iS5comm(dhcp-config)# sip-server ip 12.0.0.6 15.0.0.5

The SIP IP addresses are configured as 12.0.0.6 and 15.0.0.5. This is Option 120.
Configure SIP Server Option with two domain names.
iS5comm(dhcp-config)# sip-server domain <domain name> [<domain name>]

iS5comm(dhcp-config)# sip-server domain future.com is5com.com

The SIP domain names are configured as future.com is5com.com. This is Option 120.
Verify the assigned IP Addresses.
iS5comm(dhcp-config)# end

iS5comm# show ip dhcp server pools
```
Global Options
```
```
--------------
```
```
Code : 3, Value : 12.0.0.2
```
```
Pool Id : 1
```
```
-------------------------------------------
```
```
Subnet : 12.0.0.0
```
```
Subnet Mask : 255.0.0.0
```
```
Lease time : 95400 secs
```
```
Utilization threshold : 50%
```
```
Start Ip : 12.0.0.1
```
```
End Ip : 12.0.0.100
```
```
Subnet Options
```
```
--------------
```
```
Code : 120, Value : future.com, is5com.com
```
Note: This option will be offered to the DHCP clients only when there is no host specific option for the client. If this option is not configured and there is no host option too, then the global option will be preferred.