KbA0005: Service Port

Description

CopperCube requires a static IP address when it is deployed on-site. By default, its primary Ethernet port (LAN1) is assigned to Dynamic Host Configuration Protocol (DHCP) since it is not possible to know the user’s destination configuration in advance. Also the IP address of the CopperCube will be unknown if DHCP is selected, and without knowing the assigned IP address it is not possible to access the Coppercube’s User Interface to configure the desired static IP [A classic catch-22].

Solution

To solve this problem the CopperCube is equipped with a second Ethernet port (LAN2) called the Service Port. This port is assigned a static IP address (169.254.8.29) allowing easy connection to the device for configuration purposes. Why this specific address?

The IP address range 169.254.1.1 to 169.254.254.254 has been reserved by the IETF (Internet Engineering Task Force) for this purpose. It is called link-local addressing (see http://en.wikipedia.org/wiki/Link-local_address). Link-local addressing is a type of private IP addressing, that cannot be routed beyond the immediately physically connected devices. It is the foundation upon which Zero-configuration-IP-networking (Zeroconf) is built. Zeroconf is also known as Bonjour (Apple), APIPA (Automatic Private IP Addressing) (Microsoft), and Avahi (Linux). (see: http://en.wikipedia.org/wiki/Zero-configuration_networking)

So how does this help me?

You most likely are using a Windows PC to configure your CopperCube. A windows PC (without a static IP) when it can’t find a DHCP server; will assign itself an IP in the 169.254.x.x range, as per the Microsoft APIPA. Due to this default behavior (available since XP), the PC can communicate with other IP devices in the same 169.254.x.x range (i.e. the CopperCube) with no user network configuration. Simply connect your PC to the Coppercube and the two are communicating. That’s it!

There must be a catch. What are the exact steps and limitations?

Yes, there are two important limitations:

  1. The PC and the CopperCube must reside on the same Ethernet segment. Meaning they are directly connected, either by an Ethernet cable or via a network switch. 169.254.x.x IP packets will NOT pass through a router.
  2. Only one CopperCube may be on the Ethernet segment. Multiple CopperCubes will conflict with one another as they all use the same static 169.254.8.29 IP Address.

What is the workflow I must follow?

  1. On your PC disable all wireless networking. You don’t want it to obtain an IP via the wireless network.
  2. On your PC ensure the wired Ethernet port is assigned to use DHCP.
  3. On your PC unplug all Ethernet cables. You want to ensure the PC cannot obtain its IP address via DHCP.
  4. Connect the PC to the CopperCube (LAN2) with an Ethernet cable. [A switch, hub, or flip-cable are not required].
  5. Reboot the PC. Verify (via ipconfig or networks GUI) that the PC assigned itself 169.254.x.x IP address.
  6. Using your browser, surf to 169.254.8.29 (the CopperCube).
  7. The CopperCube User Interface should appear (within 10 seconds).
  8. Proceed to configure your CopperCube as required.