Network

Mikrotik Switches flushing Unicast

Some changes may take some time to take effect due to already learned MAC addreses. In such cases flushing Unicast Forwarding Database can help: /interface ethernet switch unicast-fdb flush

What is IP Address?

Internet Protocol Address (or IP Address) is an unique address that computing devices use to identify itself and communicate with other devices in the Internet Protocol network. Any device connected to the IP network must have an unique IP address within its network. An IP address is analogous to a street address or telephone number in that it is used to uniquely identify a network device to deliver mail message, or call ("view") a website.

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What is Subnet Mask?

What is Subnet Mask?

An IP address has two components, the network address and the host address. A subnet mask separates the IP address into the network and host addresses (<network><host>). Subnetting further divides the host part of an IP address into a subnet and host address (<network><subnet><host>). It is called a subnet mask because it is used to identify network address of an IP address by perfoming bitwise AND operation on the netmask.

A Subnet mask is a 32-bit number that masks an IP address, and divides the IP address into network address and host address. Subnet Mask is made by setting network bits to all "1"s and setting host bits to all "0"s. Within a given network, two host addresses are reserved for special purpose. The "0" address is assigned a network address and "255" is assigned to a broadcast address, and they cannot be assigned to a host.

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What is MAC Address?

MAC, Media Access Control, address is a globally unique identifier assigned to network devices, and therefore it is often referred to as hardware or physical address. MAC addresses are 6-byte (48-bits) in length, and are written in MM:MM:MM:SS:SS:SS format. The first 3-bytes are ID number of the manufacturer, which is assigned by an Internet standards body. The second 3-bytes are serial number assigned by the manufacturer.

MAC layer represents layer 2 of the TCP/IP (adopted from OSI Reference Model), where IP represents layer 3. MAC address can be thought of as supporting hardware implementation whereas IP address supports software implementation. MAC addresses are permanently burned into hardware by hardware manufacturer, but IP addresses are assigned to the network devices by a network adminstrator. DHCP relies on MAC address to assign IP addresses to network devices.

How do I find a MAC address of network device?

Operating Systems support various command-line and GUI utilities to allow users to find MAC address of the system. On Unix variants including Solaris and Linux support "ifconfig -a", "ip link list" or "ip address show" command that displays MAC address of the network device among other useful information. Windows including NT, 2000, XP and 2003 support "ipconfig /all" command that displays MAC address. On a MacOS, one can find MAC address by opening "System Preferences", then selecting "Network".



Ethernet Overview

1. What is Ethernet?

Ethernet is the most widely used local area network (LAN) technology, that defines wiring and signaling standards for the physical layer of TCP/IP. Ethernet was originally standardized as IEEE 802.3 with a data transmission rate of 10 Mb/s. Newer versions of Ethernet were introduced lately to offer higher data rates. Fast Ethernet and Gigabit Ethernet support data rates of 100 Mbps and 1 Gbps (1000 Mbps) respectively. An Ethernet LAN may use coaxial cable (10Base2), unshielded twisted pair wiring (10BaseT, 100BaseT and 1000BaseT), or fiber optic cable. Ethernet devices compete for access to the network using a protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). With prosperity of Internet, Wi-Fi, the wireless LAN technology standardized by IEEE 802.11, is used in hybrid with Ethernet LAN to offer portability.


2. Ethernet Standards

IEEE 802.3 is the signaling standards for Ethernet, and IEEE 802.11 is the standards for Wi-Fi. The standards documents may be obtained free of charge at the following website: http://standards.ieee.org/getieee802/

What is TCP/IP?

TCP/IP, Transmission Control Protocol/Internet Protocol, is a suite of communications protocols used to interconnect network devices on the Internet. TCP/IP implements layers of protocol stacks, and each layer provides a well-defined network services to the upper layer protocol. TCP and IP are the two protocols used by TCP/IP, as well as the (higher) application, (lower) data link and (lower) physical layer protocols.
LayerProtocols
5. ApplicationDNS, FTP, HTTP, IMAP, POP3, SMTP, SSH, Telnet, SSL, ...
4. TransportTCP, UDP, ...
3. NetworkIP (IPv4, IPv6), ICMP, ARP, ...
2. Data Link802.3 (Ethernet), 802.11 (Wi-Fi), PPP, ...
1. PhysicalEthernet (NIC), Wireless (NIC), Cat 5/RJ-45, ...


Ethernet Overview

1. What is Ethernet?

Ethernet is the most widely used local area network (LAN) technology, that defines wiring and signaling standards for the physical layer of TCP/IP. Ethernet was originally standardized as IEEE 802.3 with a data transmission rate of 10 Mb/s. Newer versions of Ethernet were introduced lately to offer higher data rates. Fast Ethernet and Gigabit Ethernet support data rates of 100 Mbps and 1 Gbps (1000 Mbps) respectively. An Ethernet LAN may use coaxial cable (10Base2), unshielded twisted pair wiring (10BaseT, 100BaseT and 1000BaseT), or fiber optic cable. Ethernet devices compete for access to the network using a protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). With prosperity of Internet, Wi-Fi, the wireless LAN technology standardized by IEEE 802.11, is used in hybrid with Ethernet LAN to offer portability.


2. Ethernet Standards

IEEE 802.3 is the signaling standards for Ethernet, and IEEE 802.11 is the standards for Wi-Fi. The standards documents may be obtained free of charge at the following website: http://standards.ieee.org/getieee802/