Product Documentation

DHCP server and DHCP relay

Netscaler SD-WAN introduces the ability to use Standard or Enterprise Edition appliances as either DHCP Servers or DHCP Relay agents. You can configure your appliance to issue IP addresses using DHCP or forward DHCP packets between clients and servers.

Note

  • DHCP Server supports only IP Pool based address assignment.
  • DHCP Relay does not support multiple DHCP Server IP address assignments.

How to enable DHCP server

NetScaler SD-WAN appliances can be configured as DHCP server that assigns and manages IP addresses from specified address pools within the network to DHCP clients. The DHCP server can be configured to assign more parameters such as the IP address of the Domain Name System (DNS) server and the default router. DHCP server accepts address assignment requests and renewals. The DHCP server also accepts broadcasts from locally attached LAN segments or from DHCP requests that are forwarded by other DHCP relay agents within the network.

To enable DHCP server:

  1. Navigate to Configuration > Appliance Settings > Network Adapters. In the Network Adapters page, look for the Management Interface DHCP Server pane.

  2. Click the Enable DHCP Server checkbox to start the server, then enter the Lease Time (in minutes), the Domain Name, and define the IP Address range by entering a Start IP Address and an End IP Address.

    Note

    The server IP address pool should be within the management network.

    localized image

  3. Click the Change Settings button to finish configuring the DHCP Server.

    Note

    If you plan to use DHCP Server on an SD-WAN appliance configured for High Availability (HA), do not configure the service on both the Active and Standby appliance. Doing so leads to duplicate IP addresses on the defined management network.

  4. Click Show Client to view the current DHCP clients, and click Clear Clients to release the DHCP Client leases.

How to enable DHCP relay

A DHCP relay agent is a host or router that forwards DHCP packets between clients and servers. Network administrators can use the DHCP Relay service on the management port of the SD-WAN (Standard or Enterprise () Editions) appliances to relay requests and replies between local DHCP Clients and a remote DHCP Server. This allows local hosts to acquire dynamic IP addresses from the remote DHCP Server. Relay agent receives DHCP messages and generates a new DHCP message to send out on another interface.

To enable DHCP relay service:

  1. Navigate to Configuration > Appliance Settings > Network Adapters. In the Network Adapters page, look for the Management Interface DHCP Relay pane.

  2. Click the Enable DHCP Relay checkbox to enable the service. Enter the DHCP Server IP Address and click the Change Settings button to begin using your appliance as a DHCP Relay Agent.

    Note

    If you plan to use DHCP Relay service on an appliance configured for High Availability (HA), do not configure the service on both the Active and Standby appliances. Doing so leads to duplicate IP addresses on the defined management network.

    localized image

The runtime Virtual IP address, Subnet Mask, and Gateway settings are logged and archived in a log file called “SDWANVW_ip_learned.log.” Events are generated when Dynamic Virtual IPs are learned, released, or expired, and when there is a communication issue with the learned Gateway or DHCP server. Or when duplicate IP addresses are detected in the archived log file. If duplicate IPs are detected at a site, Dynamic Virtual IP addresses are released and renewed until all Virtual Interfaces at the site obtain unique Virtual IP addresses.

To monitor DHCP client WAN links:

  1. In the Virtual WAN > Enable/Disable/Purge Flows page, the DHCP Client WAN Links table provides the status of learned IPs.

  2. You can request to renew the IP, which refreshes the lease time. You can also choose to Release Renew, which issues a new IP address with a new lease.

    localized image

DHCP server and DHCP relay