Week 6 Notes - WanderlustPenguin/Charles-Tech-Journal GitHub Wiki

Lectures

  • subnetting: taking one network address and splitting it into smaller subnetworks

  • MAC address: layer 2, 8 bit, hexadecimal

  • IP address: layer 3, 32 bit, binary, contains the Network ID and the Host ID

  • Network ID covers from 8 to 30 bits, Host ID is however many bits are left over. Network is 1 and host is 0 in binary in subnet mask

  • 255.255.255.0 is /24, and takes up 24 bits since each decimal area is worth 8 bits, written 11111111.11111111.11111111.00000000 in binary

  • 255.255.240.0 is /20, and takes up 20 bits

  • 255.255.252.0 is /22, and takes up 22 bits, written 11111111.11111111.11111100.00000000 in binary

  • number of Usable IPs is total IPs-2. first non usable is the .0 value used for broadcasting, and the other is the network at .255

  • decimal to binary: add up the part of the pattern the 1 is. above is large numbers, below are 1s and 0s, add the large number value of the one. large values work on power of 2, with the furthest right number being 2^0, and then moving 2^1,2^2 and so on

  • Supernet/Supernetwork: CIDR block

  • CIDR/supernetworking:classless interdomain routing, intended to allow full utilization of otherwise used IP space

  • wasteless IPs are classless

  • usable addresses can be found with 2^(32-/xx)

  • subnet mask tells us how many bits are reserved for the network, and how many are allowed for the host

Labs

  • DECBIN2 in excel converts the IP into binary if done individually for each decimal area
  • Same applies to netmask
  • The net mask is determined by doubling the amount subtracted for each layer down from a .255, i.e. -1,-2,-4,-8
  • the .255 /xx are the multiples of 8, with /8 being .255.000.000.000, and /32 being .255.255.255.255
  • Packet tracer automatically gives a subnet mask, it's always a single default, which is sometimes wrong
  • default gateway is just the network