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4.3 The Internet Protocol, part 1

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💫 Short Summary

The video covers the Internet's network layer, focusing on IPv4 protocol, addressing, NAT, IPv6, ICMP protocol, and IP Datagram format. It explains IP addresses, subnetting, DHCP process, and BGP routing protocol in relation to ISPs and address allocation. The exhaustion of IPv4 led to the development of IPv6 with a larger address space. Vint Cerf discusses the early days of the Internet and the decision-making process for the address space size. Consideration for a 128-bit address space was made to avoid transition issues.

✨ Highlights
📊 Transcript
Overview of Internet network layer including IPv4 protocol and addressing.
Importance of addressing for ISPs, administrative boundaries, hardware, and global issues.
Explanation of network address translation (NAT) and IPv6.
Significance of IP protocol in data gram format, addressing structure, interpretation, and packet handling conventions.
Introduction to ICMP protocol and detailed discussion of IP Datagram format fields.
Overview of IP datagrams and IPv4 vs. IPv6.
IP datagrams have a maximum size of 64 K bytes, but are typically no larger than 1,500 bytes for Ethernet frames.
Service bits in the IPv4 header distinguish different types of datagrams and include two bits for explicit congestion notification.
The TTL field decrements with each router hop to prevent infinite looping.
IPv6 has fewer header fields compared to IPv4, making it more streamlined, and IP addresses identify interfaces rather than hosts or routers directly.
Summary of IP Addresses and Subnets
IP addresses are written in dotted decimal notation, with each decimal number corresponding to an 8-bit byte.
Interfaces are connected through link layer technologies like Ethernet or Wi-Fi.
Subnets contain devices that can communicate directly without passing through a router.
Subnets are defined by attaching each interface to its host or router.
Process of obtaining an IP address through DHCP.
Client broadcasts a discover message to find a DHCP server.
Server responds with an offer message, providing an IP address to the client.
Client requests the offered IP address, and the server acknowledges the request.
DHCP protocol allows for automatic allocation of IP addresses without manual configuration, crucial for networks with numerous mobile devices connecting and disconnecting.
Summary of DHCP Process
DHCP discover message is sent by the client to the DHCP server as a broadcast containing source IP address and UDP segment.
The server responds with a DHCP offer message including IP address, transaction ID, and lifetime.
The client can receive offers from multiple servers.
The final step involves an ACK message from the DHCP server assigning the IP address and configuration parameters like first hop router IP, DNS server, and netmask.
The importance of address allocation and routing in ISPs and BGP routing protocol.
ISPs allocate address prefixes to client networks and longest prefix matching is crucial in forwarding table lookup.
Example of organization one changing ISPs demonstrates the significance of advertising longer prefixes.
The relationship between address allocation, forwarding table lookup, and BGP routing protocol is highlighted.
The role of the Internet Corporation for Assigned Names and Numbers in administering and allocating the IPv4 address space is mentioned.
ICANN manages the allocation of IP addresses, DNS servers, domain names, and protocol numbers.
In 2011, ICANN allocated the last of its 32-bit address space, leading to the development of IPv6 with a larger 128-bit address space.
Vint Cerf, a founding father of the Internet, discussed the early days of the Internet and the design process for network protocols.
The decision-making process for determining the size of the address space involved global considerations and predictions for network growth per country.
Creation of a 32-bit address space with 4.3 billion possible terminations for the network in 1973.
Consideration for a 128-bit address space to avoid a painful transition.
Contemplation on the need for 3.4 times 10 to the 38th addresses for an experiment.
Questioning the feasibility of the experiment with only three networks and 500 computers.
Decision not to proceed due to discrepancies in the numbers not adding up.