Making the Internet Manageable CSE101 Sunday December 19
Making the Internet Manageable CSE-101 Sunday, December 19, 2021
The Hardware Layer The hardware layer is in charge of converting packets to bits and transmitting these bits electronically through different technologies such as “DSL”, “Fiber Optics”, “Cable” and “Twisted Pair”. We will cover how these technologies work later on in class. All machines have a Hardware address called a “MAC” address, or “Media Access Control Address”. This Address is hardcoded in to the hardware of a network interface and cannot be changed. The MAC address is used when delivering messages along a subnet. It is possible for a MAC address to have multiple IP addresses. The binding between a MAC address and IP address is handled through a process called ARP or “Address Resolution Protocol”.
The Hardware Layer Your machine will only use ARP to communicate with other devices on your own *subnet*. Machines on a subnet will tell each other what their MAC address is using ARP. This is a friendly way to exchange addresses on your own subnet without having to bother the gateway machine.
How are names transformed in to IP addresses? Humans are much better at memorizing and communicating in words than we are in numbers such as those that make up IP addresses. Your computer uses a system called “DNS” or the “Domain Name System” to translate domain names such as “google. com” to an IP address such as “ 168. 95. 1. 1”. Domain Name lookup is an iterative process. Doman Name servers are arranged in a hierarchal fashion. In the case of “cse. buffalo. edu” the “buffalo. edu” name server will defer to the “cse” name server.
How are names transformed in to IP addresses? A local DNS server will temporarily cache entries for greater speed upon subsequent lookups. Each name server only knows of its own small portion of its domain. A similar but less used system is known as WINS, or the “Windows Internet Naming System”
How are names transformed in to IP addresses?
How are names transformed in to IP addresses?
When was the last time you set up your own IP address? Addresses for widely used services such as email or web pages are known to be “static”. These addresses to not change over time and are usually manually set by someone. Usually work stations or home PCs tend to have “dynamic” addresses. These addressed are managed or “leased” by a central authority. This central authority is known as “DHCP” or Dynamic Host Control Protocol. When you tell your computer to use “UB_Wireless”, it will ask UB’s DHCP server for an IP address and all associated setting such as the “gateway”, “DNS server” and “subnet mask”.
When was the last time you set up your own IP address? DHCP makes it possible to hide all the details of the IP protocol from internet users. What happens when there is no server to answer your request? Your Pc will guess its own address and assign an “AAIPA” or automatically Assigned IP Address. You will know this is happening if your machines IP address starts with a “ 169…. ”.
When was the last time you set up your own IP address?
When was the last time you set up your own IP address?
When was the last time you set up your own IP address?
How old is the TCP/IP protocol? The TCP/IP protocol is over 30 years old!! Nearly no other aspect of computing has lasted as long as the TCP/IP protocol without undergoing major changes. The internet looks far different today than it did 30 years ago. It has been able to last due to the robustness, and modularity of its architecture and protocol stacks. Protocols used on the internet have an “open” implementation. These implementations are public to everyone. The entire community of internet users also has the right to contribute to newer protocols.
How old is the TCP/IP protocol? The Internet is extremely adaptable to change both in its topology, and protocols uses. We currently use the TCP/IP protocol known as “IPV 4”, or “Internet Protocol Version 4”. One of the major drawbacks of IPV 4 is that it is running out of address space! IPV 4 can support a theoretical total of 4, 294, 967, 296 addresses. In practice this turns out to be fewer addresses. Addresses are estimated to run out between 2010 – 2012. IPV 6 remediates this problem and is slowly replacing IPV 4. IPV 6 can support up to 2128 addresses.
- Slides: 14