How Bypass works
Bypass-supporting NICs have a switch between the network interface and a port, which in case of malfunction redirects traffic pass the NIC controller.
Watch Dog Timer responds to a critical event (frozen OS or software, power off, etc.) in about half a second and switches traffic on physical level. Admins can also setup bypass functioning manually. Altogether there are 3 modes: Normal, Bypass and Disconnect.
1. In Normal mode the ports function as two separate network interfaces.
2. When Bypass mode is activated, the ports short-circuit each other, while traffic is not going to network interfaces – but directly between them. This scheme will function even if power is completely off.
3. In Disconnect mode TX links to interface disconnect, and NIC ceases to operate.
Bypass usage scenarios
This functionality is added to systems whose shutdown is critical for an entire network infrastructure: Firewall, IPS, IDS, DPI, access servers, gateways, etc. The technology allows decreasing the number of situations, where subscribers have no Internet access. Bypass “excludes” only and exactly the function for which the malfunctioning device was responsible.
Yet another Bypass usage scenario is scheduled maintenance works on IT infrastructure. It makes the procedure convenient for specific engineers – as they need no tweaking with traffic redirection: simply to switch off a server is enough for conducting maintenance.
Stingray SG has an intergated Bypass. It also supports external Bypass of any vendor.