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