Demultiplexing And How It Works
In this article I will explain demultiplexing and how it works by walking through a .pcap file taken from the lab in the screenshot below. We will focus on the data flowing from PC1 and SW1 to R1’s ingress port. Demultiplexing (DEMUX) is the method in which the TCP/IP stack uses to determine if datagrams have been received correctly and if so, how should they be processed. Demultiplexing looks at certain fields at each layer of the TCP/IP stack, these fields include MAC addresses, IP addresses, protocols and ports. Checksums are also accounted for to verify the datagram hasn’t been damaged during transit. Physical I sent a DHCP request from PC1 into the network and captured the request on the Gigabyte interface connecting SW1 and R1, we will use the DISCOVER .pcap file to walk through demultiplexing. As shown in figure .1 , the Ethernet frame enters the ingress interface of R1 from PC1. We have lots of information to accompany the datagram but our main focus is the Encaps...