Port Speed Negotiation vs Router Throughput Rating


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Networking Terms can be somewhat confusing and skew expectations on how your network performs. Today, we’ll cover Port Speed Negotiation vs Throughput Rating.

Port speed negotiation is the maximum speed rate capability supported by a physical port, example: a Gigabit Ethernet port can support up to 1000 Mbps. Wired routers generally use Ethernet interfaces to communicate with devices on their local network. Port speed is a measure of how fast these interfaces are able to transmit and receive data. It is largely dictated by two factors: the version of Ethernet cable plugged into the port and the speed of transmission used by the clients with which it is communicating.

The Router Throughput Rating measures more so bandwidth speed (combined Upload and Download), provided by the Manufacturer/ISP, example: WAN throughput 100Mb Bi-directional, T-1 at 1.544 Mbps, OC3 at 155Mbps, etc_. Modem speed is a measure of speed over the external interface that the router uses to communicate with a modem, rather than its internal interfaces. This is significant because modems use Wide Area Network technologies to allow routers to communicate with external clients, which are generally slower than a local Ethernet connection. As such, a router’s modem speed will likely be significantly lower than its port speed, even if the router uses the same Ethernet version to communicate with the modem as it does with other network devices.

To illustrate, the Balance One currently has a Router Throughput Rating of 600Mb Bi-Directional while having 1Gb capable WAN Ports. The WAN throughput is determined not by Port Negotiation but rather the Throughput (eg. 600Mb).