CST 311 - Week 5

 This week the topic of discussion was the Network Layer that consists of a data plane and a control plane.  What's inside a router/how do they function, Internet Protocol and the different versions, and generalized forwarding and software-defined networking (SDN) were other topics studied.

The data plane handles the forwarding function, or moving packets from router inputs to router outputs, which determines how to get a packet from the input port to the output port.  This is also a local function that happens on every router.  The control plane provides the routing functions, or finding the route taken by the packets from the source to the destination.  This is a network-wide function because all routers need to communicate with each other to determine the correct end-to-end path.

The router architecture consists of input/output ports, high-speed switching fabric, and the router processor.  The forwarding function happens in hardware in the high-speed switching fabric in a time scale of nanoseconds.  The switching fabric is where the packets are transferred from the input buffer to the output buffer known as the switched rate.  This can be done The routing function happens in software on the router and operates in milliseconds.  The goal of any router is to process packets at the rate they are received. 

The internet protocol consists of many things like how to format a datagram, IP fragmentation and assembly, IPv4 addressing, IPv6 addressing, and network address translation (NAT).  I found the NAT most interesting because of its practicality.  It allows the local network to use just one IP address for all of the local devices so outside devices only see one IP address.