On Mon, Jun 23, 2025 at 10:34 AM Craig Smith via NANOG <nanog@lists.nanog.org> wrote:
Is anyone out there aware of a fail safe switch/router/1U server where upon power failure or watchdog event 2 ports would fail to pass through
There are in fact various "Server bypass NICs". I would strongly suggest not using it simply to gather telemetry. Only if the application involves modifying, dropping, or inserting packets on the link, then you might need that insert of a software-based bridge and all the drawbacks that come with that. Bridging is a software function, and using one introduces points of failure, such as when a server system is powered on, but a software anomaly or the rate of packets exceeds the CPU's capabilities. You may incur additional latency in packet forwarding and dropped or corrupted packets. When it comes to bridges; many types of network failures are partial failures - a 50% drop rate causes major troubles, but the OS is still running, and therefore a watchdog agent sees no issue. Various units are available which can passively tap a link without inserting a device that actively participates in the link protocol. Fiber taps or copper taps; depending on the type of link. Or use the SPAN/Mirror function of existing managed switches which would be less expensive than implementing a dedicated tap. Still avoid inserting a software-based forwarding device between network endpoints which most likely cannot assure you full wire speed forwarding with the same consistency as the hardware ASIC-based forwarding routers or bridges at either side of the link being tapped, especially high packet rates on high capacity links.
Craig -- -JA