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How to set up DHCP Services on Dell Networking Wireless Instant Access Point



This Article discusses the options and how to configure DHCP Services on Dell Networking Wireless Instant Access Point




Objectives
  1. Overview of Different Assignment Modes
  2. How to Configure Distributed DHCP Scopes
  3. How to Configure Local, Local,L3, and Centralized,L2 DHCP Scopes
  4. How to set the IP DHCP Pool Address Range

Overview of Different Assignment Modes

The Virtual Controller supports different modes of DHCP address assignment. With each DHCP address assignment mode, various client traffic forwarding modes are associated.

Instant supports the following DHCP assignment modes:

Distributed DHCP Modes:
  • Distributed, L2 - In this mode, the Virtual Controller acts as the DHCP server, but the default gateway is in the data center. Based on the number of clients specified for each branch, the range of IP addresses is divided. Based on the IP address range and client count configuration, the DHCP server in the Virtual Controller controls a scope that is a subset of the complete IP Address range for the subnet distributed across all the branches. This DHCP Assignment mode is used with the L2 forwarding mode.
  • Distributed, L3 - In this mode, the Virtual Controller acts as the DHCP server and the default gateway. Based on the number of clients specified for each branch, the range of IP addresses is divided. Based on the IP address range and client count configuration, the DHCP server in the Virtual Controller is configured with a unique subnet and a corresponding scope.

Other DHCP Modes:
  • Local - In this mode, the Virtual Controller acts as both the DHCP Server and the default gateway. The configured subnet and the corresponding DHCP scope are independent of subnets configured in other IAP clusters. The Virtual Controller assigns an IP address from a local subnet and forwards traffic to both corporate and non-corporate destinations. The network address is translated appropriately and the packet is forwarded through the IPSec tunnel or through the uplink. This DHCP assignment mode is used for the NAT forwarding mode.
  • Local, L3- In this mode, the Virtual Controller acts as a DHCP server and the gateway, and assigns an IP address from the local subnet. The IAP routes the packets sent by clients on its uplink. This mode does not provide corporate access through the IPsec tunnel. This DHCP assignment mode is used with the L3 forwarding mode.
  • Centralized, L2- In this mode, the Virtual Controller does not assign an IP address to the client. However, the Virtual Controller acts as DHCP Relay that forwards the DHCP traffic to the controller over the VPN tunnel. The IP address is obtained from either the controller, or a DHCP server behind the controller serving the VLAN of the client. This DHCP assignment mode also allows you to add the DHCP option 82 to the DHCP traffic forwarded to the controller


How to Configure Distributed DHCP Scopes


Instant allows you to configure the DHCP address assignment for the branches connected to the corporate network through VPN. You can configure the range of DHCP IP addresses used in the branches and the number of client addresses allowed per branch. You can also specify the IP addresses that must be excluded from those assigned to clients, so that they are assigned statically.

To configure distributed DHCP scopes such as Distributed,L2 or Distributed,L3:
  1. Click More>DHCP Server at the top right corner of the Instant Main window. The DHCP Server window is displayed.
  2. To configure a distributed DHCP mode, click New under Distributed DHCP Scopes. The New DHCP Scope window is displayed.
  3. Based on type of distributed DHCP scope, configure the following parameters:
Name Description
Name Enter a name for the DHCP scope.
Type Select any of the following options:
Distributed, L2- On selecting Distributed, L2, the Virtual Controller acts as the DHCP Server but the default gateway is in the data center. Traffic is bridged into VPN tunnel.
Distributed, L3- On selecting Distributed, L3, the Virtual Controller acts as both DHCP Server and default gateway. Traffic is routed into the VPN tunnel.
VLAN Specify a VLAN ID. To use this subnet, ensure that the VLAN ID specified here is assigned to an SSID profile.
Netmask If Distributed, L2 is selected for type of DHCP scope, specify the subnet mask. The subnet mask and the network determine the size of subnet.
Default router If Distributed, L2 is selected for type of DHCP scope, specify the IP address of the default router.
DNS Server If required, specify the IP address of a DNS server.
Domain Name If required, specify the domain name.
Lease Time Specify a lease time for the client in minutes.
IP Address Range Specify a range of IP addresses to use. To add another range, click the + icon. You can specify up to four different ranges of IP addresses.
For Distributed,L2 mode, ensure that all IP ranges are in the same subnet as the default router. On specifying the IP address ranges, a subnet validation is performed to ensure that the specified ranges of IP address are in the same subnet as the default router and subnet mask. The configured IP range is divided into blocks based on the configured client count.
For Distributed,L3 mode, you can configure any discontiguous IP ranges. The configured IP range is divided into multiple IP subnets that are sufficient to accommodate the configured client count.

NOTE: You can allocate multiple branch IDs (BID) per subnet. The IAP generates a subnet name from the DHCP IP configuration, which the controller can use as a subnet identifier. If static subnets are configured in each branch, all of them are assigned the with BID 0, which is mapped directly to the configured static subnet.
Option Specify the type and a value for the DHCP option. You can configure the organization-specific DHCP options supported by the DHCP server. To add multiple DHCP options, click the + icon. You can add up to eight DHCP options.
  1. Click Next.
  2. Specify the number of clients to use per branch. The client count configured for a branch determines the use of IP addresses from the IP address range defined for a DHCP scope. For example, if 20 IP addresses are available in an IP address range configured for a DHCP scope and a client count of 9 is configured, only a few IP addresses (in this example, 9) from this range will be used and allocated to a branch. The IAP does not allow the administrators to assign the remaining IP addresses to another branch, although a lower value is configured for the client count.
  3. The Static IP tab is displayed. The number of first and last IP addresses reserved in the subnet is displayed.
  4. Click Finish.


How to Configure Local, Local,L3, and Centralized,L2 DHCP Scopes

To configure Local, Local,L3, and Centralized,L2 DHCP scopes:
  1. Click More>DHCP Server at the top right corner of the Instant Main window. The DHCP Server window is displayed.
  2. To configure a Local, Local,L3, or Centralized,L2 DHCP scopes, click New under Other DHCP Scopes. The New DHCP Scope window is displayed.
  3. Based on type of DHCP scope, configure the following parameters:
Name Description
Name Enter a name for the DHCP scope.
Type Select any of the following options:
Local- On selecting Local, the DHCP server for local branch network is used for keeping the scope of the subnet local to the IAP. In the NAT mode, the traffic is forwarded through the IPSec tunnel or the uplink.
Local, L3-On selecting Local, L3, the Virtual Controller acts as a DHCP server and gateway. In this mode, the an IAP routes the packets sent by clients and also adds a route on the controller, after the VPN tunnel is set up during the registration of the subnet.
Centralized, L2- On selecting Centralized, L2, the Virtual Controller does not assign an IP address to the client and the DHCP traffic is directly forwarded to the controller over the IPSec tunnel. The client IP address is obtained from either the controller or a DHCP server behind the controller serving the VLAN of the client.
VLAN ID Specify a VLAN ID. To use this subnet, ensure that the VLAN ID specified here is assigned to an SSID profile.
Network Specify the network to use.
Net Mask If Local or Local,L3 is selected, specify the subnet mask. The subnet mask and the network determine the size of subnet.
Excluded address If Local,L3 is selected, specify the IP address to exclude, The value entered in the field determines the exclusion range of the subnet. Based on the size of the subnet, the IP addresses that come before or after the IP address value specified in this field are excluded.
DNS Server If required, specify the IP address of a DNS server for the Local and Local,L3 scopes.
Domain Name If required, specify the domain name for the Local and Local,L3 scopes.
Lease Time Specify a lease time for the client in minutes.
Option Specify the type and a value for the DHCP option. You can configure the organization-specific DHCP options supported by the DHCP server. To add multiple DHCP options, click the + icon.
DHCP relay Select Enabled to allow the IAPs to intercept the broadcast packets and relay DHCP requests directly to corporate network. When enabled, this feature helps reduce network traffic caused by the broadcasting of DHCP requests to the corporate network.
DHCP server Specify the IP address of the DHCP relay server.
Option82 This option is available only if Centralized, L2 is selected. Select Alcatel to enable DHCP Option 82 to allow clients to send DHCP packets with the Option 82 string.

The Option 82 string is available only in the Alcatel (ALU) format. The ALU format for the Option 82 string consists of the following:
Remote Circuit ID; X AP-MAC; SSID; SSID-Type
Remote Agent; X IDUE-MAC
  1. Click OK
How to set the IP DHCP Pool Address Range

The DHCP server is a built-in server, used for networks in which clients are assigned IP address by the Virtual Controller. You can customize the DHCP pool subnet and address range to provide simultaneous access to more number of clients. The largest address pool supported is 2048. The default size of the IP address pool is 512.

When the DHCP server is configured and if the Client IP assignment parameter for an SSID profile is set to Virtual Controller Assigned, the Virtual Controller assigns the IP addresses to WLAN or wired clients.

You can configure a domain name, DNS server and DHCP server for client IP assignment using Instant UI or CLI.


  1. Click the System link at top right corner of the Instant main window. The System window appears.
  2. In the DHCP tab, enter the domain name of the client in the Domain name text box.
  3. Enter the IP addresses of the DNS servers separated by comma(,) in the DNS server text box.
  4. Enter the duration of the DHCP lease in the Lease time text box.
  5. Select Minutes, Hours, or Days for the lease time from the drop-down list next to Lease time. The default lease time is 0.
  6. Enter the network in the Network text box.
  7. Enter the mask in the Mask text box.
  8. Click OK to apply the changes.

To provide simultaneous access to more than 512 clients, use the Network and Mask fields to specify a larger range. While the network (or prefix) is the common part of the address range, the mask (suffix) specifies how long the variable part of the address range is.








Artikelnummer: HOW11511

Sidste ændringsdato: 06/09/2016 06:28 AM


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