We have a server bypass adapter in the lab. At the same time, we realized that it is a topic we have never covered on STH. As a result, we thought it would be worthwhile to introduce a server bypass network adapter and explain what it is used for before we get to the review.
What is a Server Bypass Adapter?
Server bypass adapters are network controllers, with a twist. They can usually be configured to allow traffic to either be blocked going from port to port or continue to pass in the event that power is cut.
Here is a simple example of where one might be used. One may want to look at all traffic flows either coming into a router or just after it. The obvious choice would be to put a box with one port going to the WAN side and the other going to the LAN side.
That box often does things like inspect flows for a firewall, but can also be used for applications like proxies.
The big challenge, of course, is what happens when that box needs to be restarted, or what if a power failure happens? If that machine is inline, then there needs to be a way to keep the connection online. One technique is to use a bypass adapter that effectively allows traffic to pass even when the machine is not online.
The above is perhaps an illustration of where a server bypass adapter is used. With a normal server adapter, when power fails, traffic between the ingress and egress ports stops. With a bypass adapter, the connection can be set to either closed or to continue passing traffic from port to port. In closed mode, traffic would stop. In bypass mode, traffic “bypasses” the node even if it is offline.
Here is an example of the Silicom 100GbE bypass network adapter we are going to look at on STH soon. This is much more complex than a standard network adapter and even the 1/10GbE copper versions. These bypass adapters have been around for generations, but the newer generations with fiber are more complex.
Most of our readers, for most applications, will want standard network adapters. Still, we do have many readers looking to put together some high-end network topologies where things like a bypass network adapter can be used. There are other techniques that are used in networking to accomplish a similar task, but we wanted to at least have a quick guide. Hopefully, this helps our readers understand what a server bypass adapter is and where they are used.
Stay tuned for the Intel E810-based Silicom P4CG2BPi81 review coming soon on STH. If you have examples of where you have seen or used them, feel free to put them in the comments.