Lecture 4: TCP/IP (Feb 1)

In today’s lecture, Dr. Gunes spoke about Ethernet frames, the IP protocol and how sub-netting works. We learned the structure of the Ethernet frame and what each section of the frame is responsible for. As a class we discussed Ethernet addressing and how the 48 bit MAC addresses are used to address in a one to one. When a packet is going to be broadcasted to all the mac addresses in the sub-network the MAC address consisting of all 1’s. Internet Protocol is an extremely integral part of the internet as we know it. In class we discussed the distinct differences between MAC addressing and IP addressing. One of the interesting differences was that to broad cast to all IP addresses in the network all 0’s are used. We discussed how IP addresses are distributed across the continents and reasons for moving away from IPv4 which uses a 32 bit address towards IPv6 which uses 128 bit addresses. We talked about the different classes of IP addresses. We talked about how IP addresses have a host and network IDs and how the least significant bits can be masked to divide a sub-network and group hosts based on physical topology. Near the end of the lecture we went over Address Resolution. This is the process by which you can use the IP address of a host to query for its MAC address. Dr. Gunes ended the lecture talking about IP datagram structure and MTU’s. Over all this lecture was great for understanding the fundamentals about how IPs and MAC addresses are used at the lower layers to route traffic.