-tcp/ip addressing has three parts:
. hardware addressing using media access control (mac) address
. software addressing using ip address
. ip to hostname conversion for humans
-ip addresses identify network interfaces not machines.
-to users this fact is irrelevant but to sysadmins it is imp.
-mac address is a 6 byte unique worldwide address assigned to nic at the time of manufacture.
-mac address has two parts:
. first 3 bytes identifying the manufacturer
. last 3 bytes identifying the device (using a serial number)
-mac addresses are written as a set of 6 colon separated two digit hex
-although, the manufacturer assigned mac address is unique, sysadmins can override the h/w addr (though not recommended).
-the ip to mac address mapping is defined in the link layer of tcp/ip stack.
-the address resolution protocol (arp) enables mac to ip addr conversion & vice versa.
-ip addresses identify network interfaces on a host, but how about each process that runs on the host?
-thats where 'ports' come into play.
-ports - a 16 bit number addition to ip addr in tcp or udp to identify processes/services on a system.
-port - services mapping is defined in /etc/services.
-anyone can use any ports but only root can assign and 'listen' into ports less than 1024.
-ip address types:
. unicast - addresses unique to nics - eg: regular communimcation
. multicast - addresses targetting a set of hosts simultaneously - eg: video conferencing
. broadcast - addresses targetting all hosts on a subnet - eg: connectivity checks
. anycast - addresses that resolve to one of many possible hosts - eg: load balancing
-ipv4 addresses are 4 bytes long - written as 4 decimal numbers separated by dots
-ipv6 addresses are 16 bytes long - written as 8 two byte hex numbers separated by colons
-in ipv4, the leftmost byte of an address is the most significant byte and represents the network portion.
-in ipv4, when the leftmost byte is 127, it denotes a loopback n/w - a fictitious n/w that has no real h/w and only one host.
-the address, 127.0.0.1 always represents the current host, also referred to as the 'localhost'.
Next up, tcp/ip addressing details...
. hardware addressing using media access control (mac) address
. software addressing using ip address
. ip to hostname conversion for humans
-ip addresses identify network interfaces not machines.
-to users this fact is irrelevant but to sysadmins it is imp.
-mac address is a 6 byte unique worldwide address assigned to nic at the time of manufacture.
-mac address has two parts:
. first 3 bytes identifying the manufacturer
. last 3 bytes identifying the device (using a serial number)
-mac addresses are written as a set of 6 colon separated two digit hex
-although, the manufacturer assigned mac address is unique, sysadmins can override the h/w addr (though not recommended).
-the ip to mac address mapping is defined in the link layer of tcp/ip stack.
-the address resolution protocol (arp) enables mac to ip addr conversion & vice versa.
-ip addresses identify network interfaces on a host, but how about each process that runs on the host?
-thats where 'ports' come into play.
-ports - a 16 bit number addition to ip addr in tcp or udp to identify processes/services on a system.
-port - services mapping is defined in /etc/services.
-anyone can use any ports but only root can assign and 'listen' into ports less than 1024.
-ip address types:
. unicast - addresses unique to nics - eg: regular communimcation
. multicast - addresses targetting a set of hosts simultaneously - eg: video conferencing
. broadcast - addresses targetting all hosts on a subnet - eg: connectivity checks
. anycast - addresses that resolve to one of many possible hosts - eg: load balancing
-ipv4 addresses are 4 bytes long - written as 4 decimal numbers separated by dots
-ipv6 addresses are 16 bytes long - written as 8 two byte hex numbers separated by colons
-in ipv4, the leftmost byte of an address is the most significant byte and represents the network portion.
-in ipv4, when the leftmost byte is 127, it denotes a loopback n/w - a fictitious n/w that has no real h/w and only one host.
-the address, 127.0.0.1 always represents the current host, also referred to as the 'localhost'.
Next up, tcp/ip addressing details...
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