ICS 351: Today's plan

• network and subnetwork design

Network and Sub-network design requirements

• each host in each subnetwork needs a unique IP number
• these can be assigned statically or dynamically
• server machines usually need static IP addresses, whereas
  client machines can use static or dynamic IP addresses
• static IP addresses must be assigned manually, changing them require overhead and sometimes causes user complaints
• dynamic IP addresses are assigned by DHCP, can be changed relatively easily
• (usually) we cannot easily get new IP numbers, and the future can be uncertain!

Rational Sub-network Design

• figure out network, subnetwork, and sub-sub-network (etc) topology
• figure out the minimum current size for each subnetwork
• if additional addresses are available, estimate future growth of each subnetwork
• dynamic addresses can be reassigned more easily, so it is OK to be more generous with dynamic addresses
• if the future is uncertain, adopt a reasonable policy, e.g. all subnetworks have 27-bit netmasks and subnetworks numbers are handed out as needed

Network Design Exercise

• three routers, A, B, and C, each connected to the other two
• router A is also connected to the wider internet
• router A connects to three other subnetworks:
  • X, with at least 10 static addresses and 20 dynamic addresses,
  • Y, with at least 50 dynamic addresses,
  • and Z, with at least 2 static addresses.
• router B connects to two other subnetworks:
  • H, with at least 5 static addresses but a good chance of future growth, and
  • K, with at least 30 dynamic addresses and 30 static addresses
• router C connects to two other subnetworks:
  • P, with at least 5 static addresses
  • Q, with at least 5 dynamic addresses
• You have been given the IP address range 10.11.12.0/24
• assign IP addresses for this network