FPGA.GP.Packet Encapsulation

High level packet info. Writing packet parsers and packet generators, it is easy to get emersed in the details. Lets step back and review conceptually.

Also when asked in an interview, "what is Ethernet", this might help answer those questions.

One way to look at a tcp/ip packet is encapsulation using the OSI reference layers

Each layer of the packet is peeled back until the application receives the data from the bottom up.

                     [tcp payload]  - Layer 5 - Application

                [tcp [tcp payload]] - Layer 4 - Transport

         [ip    [ip       payload]] - Layer 3 - Network

[ethernet[ethernet        payload]] - Layer 2 - Data Link

wire                                - Layer 1 – Physical

[]

A couple of nice diagrams of an encapsulated packet.

Here is an even more detailed diagram of a layered packet with all the header content detials.

Explanation of each OSI Layer:

http://www.tcpipguide.com/free/t_OSIReferenceModelLayerSummary.htm