Direct Modem DSL Speed Vs. Router Speed

DSL Incoming Interface Speed

• With any sort of DSL network setup, the bottleneck will always be the incoming interface to the DSL modem. Standard asymmetric DSL speeds are up to 6 Mbps, while newer DSL standards, such as very-high bitrate DSL, allow for the incoming interface to receive connections as fast as 40 Mbps. With a direct Ethernet connection to the rest of the network, the DSL modem's incoming interface will always be the slowest point on the network.
  
  

DSL Outgoing Interface Speed

• The DSL outgoing interface is typically an RJ-45 Ethernet connector, designed to connect either directly to another computer or to a home router's incoming interface. The DSL outgoing interface adheres to Ethernet standards and connects at either 100 Mbps or 1 Gbps. If the end device is using a wireless connection that is several feet from the wireless router, a directly-connected DSL modem will have a faster connection.
  
  

Router Incoming Interface

• The router's incoming interface, like the DSL outgoing interface, adheres to the RJ-45 Ethernet standard and connects at either 100 Mbps or 1 Gbps, depending on the model and capabilities of the router. Additionally, the Ethernet connection between the router and the DSL modem will be that of the slowest interface. If the router supports 1 Gbps connections but the DSL modem's outgoing interface only supports 100 Mbps, the Ethernet connection between the two will be 100 Mbps.
  
  

Router Outgoing Interface

• This is the Ethernet interface that all the computers on the local network connect to. The speed will be either 100 Mbps or 1 Gbps, depending on the model router and capabilities of the computers being connected. Additionally, the router may accept wireless connections, with speeds of 54 Mbps and higher common. In the case of a wireless device being several feet from the wireless router, the speed of the wireless connection may slow down to less than that of the directly-connected DSL modem speed.