Product Documentation

Troubleshooting DHCP Management IP Address Configuration

The following are the possible scenarios that you might encounter when configuring DHCP IP address. It also includes best practices and recommendations for configuring DHCP Management IP address when deploying SD-WAN appliances.

These recommendations are applicable to all platform models of SD-WAN; Standard Edition, WANOP, and Enterprise Edition - Physical and Virtual appliances. 

Note

All hardware models of SD-WAN appliances are shipped with a factory default management IP address. Ensure that you configure the required DHCP IP address for the appliance during the setup process.

All Virtual models of SD-WAN applianes (VPX models) and appliances which can be deployed in AWS environment do not have a factory default IP address assigned. 

Appliances power on without DHCP server(s) reachable

  • Causes:
    • Ethernet management cable is disconnected
    • DHCP service is down for the connected network
  • Expected behavior
    • Appliances with DHCP service enabled will retry DHCP request every 300 seconds (default value).  The actual interval is approximately 7 minutes
    • Therefore, appliances with DHCP service enabled will acquire DHCP addresses within 7 minutes after DHCP server(s) become available. The delay ranges from 0 to 7 minutes

Assigned DHCP address expires

  • Expected behavior:
    • Appliances with DHCP service enabled will try to renew the lease before the address expires
    • Appliances start with new DHCP discovery, if the renew fails

Appliances with DHCP service enabled move from one DHCP enabled subnet to another subnet:

  • Causes: Appliances move from an assigned DHCP subnet to a different DHCP subnet
  • Expected behavior:
    • A permanent lease DHCP IP address assignment might require the appliances to be rebooted to acquire an IP address from the new DHCP server.
    • Upon DHCP lease expiration, appliances might re-initiate DHCP discovery protocol, if current DHCP server is not reachable.
    • Appliances will acquire new IP addresses with a delay of 8 minutes. The gateway IP address is not modified in the GUI and CLI.  It is updated after the reboot process is completed.

Recommendation

  • Always assign permanent lease for DHCP addresses assigned to SD-WAN appliances (physical/virtual). This will allow appliances to have predictable management IP address.