DHCP Configuration

To configure DHCP options:

1. Click VNS > Topologies > General and enable Layer 3.
2. From the DHCP drop-down list, select one of the following options and click Configure.
   • Local Server if the controller's local DHCP server is used for managing IP address allocation.
   • Use Relay if the controller forwards DHCP requests to an external DHCP server on the enterprise network. DHCP relay bypasses the local DHCP server for the controller and allows the enterprise to manage IP address allocation to a VNS from its existing infrastructure.
3. If you selected Local Server, the following window displays. Configure the following parameters:
   

   DHCP Configuration

   

   1. In the Domain Name box, type the external enterprise domain name server to be used.
   2. In the Lease default box, type the default time limit. The default time limit dictates how long a wireless device can keep the DHCP server assigned IP address. The default value is 36000 seconds (10 hours).
   3. In the DNS Servers box, type the IP Address of the Domain Name Servers to be used.
   4. In the WINS box, type the IP address if the DHCP server uses Windows Internet Naming Service (WINS).
   5. Check the Enable DLS DHCP Option checkbox if you expect optiPoint WL2 wireless phone traffic on the VNS. DLS is a Siemens application that provides configuration management and software deployment and licensing for optiPoint WL2 phones.
   6. In the Gateway field, type the controller‘s own IP address in that topology. This IP address is the default gateway for the topology. The controller advertises this address to the wireless devices when they sign on. For routed topologies, it corresponds to the IP address that is communicated to wireless clients as the default gateway for the subnet. (wireless clients target the controller's interface in their effort to route packets to an external host).

      For a Bridge traffic locally at the EWC topology, the IP address corresponds to the controller's own point of presence on the VLAN. In this case, the controller's interface is typically not the gateway for the subnet. The gateway for the subnet is the infrastructure router defined to handle the VLAN.

   7. The Address Range boxes (from and to) populate automatically with the range of IP addresses to be assigned to wireless devices using this VNS, based on the IP address you provided.
      • To modify the address in the Address Range from box, type the first available address.
      • To modify the address in the Address Range to box, type the last available address.
      • If there are specific IP addresses to be excluded from this range, click Exclusion(s). The DHCP Address Exclusion dialog is displayed.
        

        DHCP Address Exclusion

        

   • In the DHCP Address Exclusion dialog, do one of the following:
     • To specify an IP range, type the first available address in the From box and type the last available address in the to box. Click Add for each IP range you provide.
     • To specify an IP address, select the Single Address option and type the IP address in the box. Click Add for each IP address you provide.
     • To save your changes, click OK.
     1. The Broadcast Address box populates automatically based on the Gateway IP address and subnet mask of the VNS.
     2. Click Close.
4. If you selected Use Relay, a DHCP window displays.
   1. in the DHCP Servers box, type the IP address of the DHCP server to which DHCP discover and request messages will be forwarded for clients on this VNS. The controller does not handle DHCP requests from users, but instead forwards the requests to the indicated DHCP server.
      

      Note

      The DHCP Server must be configured to match the topology settings. In particular for Routed topologies, the DHCP server must identify the controller's interface IP as the default Gateway (router) for the subnet. Users intending to reach devices outside of the subnet will forward the packets to the default gateway (controller) for delivery upstream.
5. To save your changes, click Save.