Week 51 / 2022
Commands
exa, ls alternative.hurl, run and test HTTP requests with plain text..procs, ps alternative.
Networking
lspci, list all PCI (a local computer bus for attaching hardware devices in a computer..) devices.- The network controller (NIC) implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet or Wi-Fi.
- The physical layer performs bit-by-bit or symbol-by-symbol data delivery over a physical transmission medium. It provides a standardized interface to the transmission medium, including a mechanical specification of electrical connectors, an electrical specification of transmission line signal level and impedance.
- Flow control in DLL is done to prevent the flow of data frame at the receiver end. The source machine must not send data frames at a rate faster than the capacity of destination machine to accept them. 1: Feedback-based Flow Control, 2: Rate-based Flow Control, a built-in mechanism in protocol will just limit rate at which data is being transferred by sender without any feedback from receiver. Stop-and-Wait, only one of frames can be in transmission at a time. Sliding Window,
- A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to digital data.
- test goodreads embedded.
Stanislav Shalunov internet
- You have to understand the basics or you'll remain a layman for the rest of your life.
- We'll be just gaining an understanding.
- Thin Ethernet as an example of the physical layer
- Thin Ethernet = 10Base2, 10Mbps, 2: media, coaxial cable that has two wires.
- Devices connected to a typical Ethernet are Network Interface Controllers, or NICs; they are also called Ethernet cards. Naturally, NICs are not all alone, but installed into something like a computer, or a printer, or whatever (the nature of the host is not essential at this point).
- Ethernet cards are assigned Media Access Control (MAC) addresses (or hardware addresses) at factories.
- A MAC address is 6 bytes long. No two Ethernet cards have the same hardware address. This is achieved by assigning three-byte pre xes to manufacturers
- Collisions? two (or more) NICs may want to start talking simultaneously.
- one MAC address reserved for special purposes:
ff:ff:ff:ff:ff:ff, Packets addressed to this MAC address are called broadcast packets, and the act of sending such packets is called broadcasting. - A LAN can only have a limited number of hosts. Our goal is to build a very large Wide Area Network (WAN). So, it looks natural to connect several LANs together.
- MAC
- ..Now it became apparent that MAC addresses are not suitable for building a large network.
- ..We'll build a different protocol on top of Ethernet, and make it scalable.
- IP
- ..The Internet Protocol, or IP uses 32-bit (4-byte) addressing; the addresses are assigned to make routing (getting packets to their destinations) easier.
- It should be stressed that it is interfaces that have IP numbers. Not hosts. Not users. Not programs.
- Address Resolution Protocol (ARP)
- how IP addresses correspond to MAC addresses in order to actually communicate.
- address resolution = The process of figuring out MAC address by an IP address (within a LAN)
المخرج الوحيد by عبدالله سعيد الشهري
My rating: 5 of 5 stars