Product and Software: The second Ethernet port is supported on only the AP-70/AP-2E hardware and on all ArubaOS versions, but this article focuses on ArubaOS 3.x.
The original use of the second Ethernet port on an AP-70 was for redundancy. In almost all cases, customers cannot justify the cost of running a second Ethernet cable. In the RAP application, we can use either Ethernet port on an AP-70 to bridge traffic to and from a local LAN. One of the more popular applications is a VoIP application to tunnel a VoIP phone back to a corporate PBX. The AP-2E is an AP-70 with no radio interfaces.
Why would we use the second Ethernet port?
Customers will use the second port to bridge to local services or resources. The second application is to tunnel and protect wired application back to a corporate subnet. The second Ethernet port can also be implemented as a port saver. We can run a single Ethernet port to an AP-70 and also support an Ethernet device on a single wiring run.
If we configured a RAP SSID in bridge mode, we would be able to extend the broadcast domain to Ethernet 1. The bridged SSID could also extend to Ethernet 0. Please note that the "Wired AP enable" will need to be selected to break the virtual interface that both Ethernet port would share.
We can configure the port to be "trusted", but the device would need the ability to perform either a L3 or L2 authentication. For devices that cannot pass the authentication process, there are two options. We can either open up the "logon" role or make the port trusted.