Computer networks -- 2007-2008 -- 9

From Wikiversity
Important! These pages are somehow outdated and it is recommended to consult the newer version at Computer networks -- 2008-2009 -- (by Ciprian Crăciun).

Quick links:


  • topics:
    • routing purpose and principles;
    • routing types:
      • static routing;
      • dynamic routing;
      • (default routing);
    • routing protocols:
      • RIP -- Routing Information Protocol;

Routing tools[edit]


ip route[edit]

  • ip man page -- see ip route - routing table management section;



This is the fifth assignment, so please commit it to the folder assignment-05.

In this assignment you will have to plan the deployment of an enterprise network.


  • our enterprise wants to build a network;
  • there are seven departments, and for each department we want to have a separate LAN;
  • the departments have the following number of hosts -- not including the LAN's router:
    • 28, 30, 91, 55, 200, 126, 47;
  • we want to obtain full interconnectivity at IP layer between these departments;
  • in order to communicate between LANs we shall use only routers;
  • each LAN will have exactly one router -- we shall call these internal routers;
  • each internal router can be connected with one or more internal routers;
  • we want to allow our hosts to access the Internet; thus we have an exit router that is connected to an ISP; this exit router' is connected to exactly one internal router -- we shall call this exit router the external router;
  • we shall use only point-to-point connections between routers;


  • design the network topology -- more exactly how must we connect the internal routers -- so that we fulfill the following requirements;
  • we want to keep the number of connections to a minimum possible;
  • the route from each LAN to each other LAN must not be longer than three hops -- meaning that it must not pass through more than 3 routers (one the source LAN router, the second one an intermediate, the third one the destination LAN router);
  • the requirement of at most 3 hops does not apply for the packets which exit on the Internet;
  • we don't want to pass all the traffic through one central router; we would like to obtain a balanced topology;
  • we want to use public global class C IP addresses for all the hosts; but by using VLSM we want to keep the number of used classes to a minimum;
  • create a table in which, for each LAN, you must specify:
    • the network address (in CIDR notation);
    • the netmask;
    • router internal IP address;
    • hosts IP address range;
    • the total number of usable IP addresses;
    • broadcast address;
    • the number of existing hosts (from the list given above);
    • the number of used IP addresses for the hosts and the router;
    • the number of unused (free) IP addresses;
  • for the point-to-point connections between the routers we shall use a private C class for addresses;
  • create a table in which, for each router (both internal and external), you must specify:
    • router IP addresses -- one for the LAN (where the case), and one for the point-to-point connections;
    • static routing table so that the number of hops requirements is fulfilled, and to allow the internet access;


  • the number of usable IP addresses in a sub-network is from the second one up to the previously last one;
  • usually the first usable IP address is assigned to the router;
  • a point-to-point connection can be seen as a network in which we have only two computers (in our case the routers);
  • usually for a point-to-point connection we use a /30 network;

As a conclusion on SVN there must be a document (doc, odf or pdf) which contains:

  • the network diagram (you could depict only the routers), with all the IP addresses;
  • the table that contains the information for each network;
  • the table that contains the routing table of each of the eight routers (both internal and external one);