KB23329 - How to assign an IP address on different subnets via the DHCP server

This article describes the possibility of creating a scope on a DHCP server to assign IP addresses to Network Connect users, which are different than the PCS (Pulse Connect Secure) internal port subnet.


 

Example 1:

• DHCP Server Scope: 2.2.2.10-20/24
• PCS Network Connect Server IP Address: 2.2.2.3/24
• DHCP server 1.1.1.2/24 <-> 1.1.1.1/24 Router 2.2.2.1/24 <-> 2.2.2.2/24 PCS Internal Port.
• The PCS internal port is in a different network to the DHCP server, so the Router performs DHCP relay. 
• This scenario works; however a DHCP scope has to be used; which is a different network to the PCS Internal Port.

Example 2:

• DHCP Server Scope: 3.3.3.10-20/24
• DHCP server 1.1.1.2/24 <-> 1.1.1.1/24 Router 2.2.2.1/24 <-> 2.2.2.2/24 PCS 2500 Internal Port.
• The PCS does not have an interface in the 3.3.3.0/24 network and you cannot add any IP address from this network as a Virtual Port of the Internal Port.  
• So, you cannot set the Network Connect Server IP Address to an IP address in the 3.3.3.0/24 network.
• Consequently, the GIADDRESS in the relayed DHCP Request is the IP address of the 2.2.2.2/24 Internal Port.
• The DHCP Server does not match this with a configured scope and cannot allocate any IP address.

External pools can be used; but you need to specify option 118 in the NC profile's DHCP settings; it is used for IPv4 Subnet selection option.

Format: <option number> <network-address for the ip-subnet> <type ip-address>

The option 118 informs the DHCP-server, the pool from which it should lease an IP. The option number might change; regarding the server software, 118 is used in ISC DHCP.