We're having a strange issue with a particular dual wan configuration. This is using a NetVanta 3448. It's running NV3448A-R12-3-3.biz firmware.
We two WAN circuits, an ethernet over fiber link (primary) and a broadband connection. Generally, when they are both plugged there is no issue. When the primary circuit goes down, traffic automatically fails over to the broadband connection as it has for a few years.
Recently, we noticed the primary WAN link flapping. This only happens when both connections are plugged in. We've had the carrier out multiple times and we've replaced our equipment and cabling. If we hook a laptop up to the primary circuit, it tests clean out to the internet.
We're at a loss. It almost seems as if there are timing issues on the 3448. Has anyone else run into this?