1. Subnetting the subnet RD-CSY3021-2008/09

2.  Company with 200 hosts  Assigned class C network 195.10.1.0/24  Want 6 different LANs  Subnet class C network using mask 255.255.255.224 (/27)  Whole network has the same subnet mask or supports equal number of hosts on all the sub-networks ◦ Is this a problem? ◦ Why? ◦ What should be done to solve it ? RD-CSY3021-2008/09

3.  VLSM Subnets a subnet ◦ VLSM divides a network into subnets of various sizes to prevent wasting IP addresses  Uses up wasted addresses  Conserves address space on WAN links  Point-to-point link only needs 2 addresses  With VLSM point-to-point links can use a /30 mask RD-CSY3021-2008/09

4.  Variable Length Subnet Masking allows division of address space based on the size of networks ◦ Start with network requiring the most addresses ◦ Create a subnet mask  (use CIDR – Classless Inter Domain Routing) ◦ Subnet the subnet as needed to provide address space required for other subnets  Be logical – start at beginning or end or address space  Addresses must be contiguous to enable route summarization RD-CSY3021-2008/09

5. Question  If an ISP has a 200.1.1.0 Network, he wants to give assign to 5 customers who need 20, 12, 6, 25, 18 hosts. ◦ What should the subnet mask be? ◦ What is the address range in each subnet? ◦ What should the routing table entries be? ◦ Can it be done efficiently to conserve IP addresses? RD-CSY3021-2008/09

8.  You are required to connect two networks in Brisbane to those in Perth, having the following requirements:  Brisbane needs to support 25 hosts each on the two networks  Perth office needs to support 5 and 10 hosts in its two offices  You may use only 128.186.1.0 /24 RD-CSY3021-2008/09

9. Office#hosts#host bits#usable hosts subnet Brisbane25530/27 Brisbane25530/27 Perth10414/28 Perth536/29 WAN222/30 RD-CSY3021-2008/09

10.  Sort the subnet requirements by size, largest subnet first.  For each required subnet, allocate address space out of the smallest available subnet  128.186.1.0/27  128.186.1.32/27  128.186.1.64/27  128.186.1.96/27  128.186.1.128/27  128.186.1.160/27  128.186.1.192/27  128.186.1.224/27 RD-CSY3021-2008/09

11. subnetsHosts availablenetworks 1.0/27321/8Brisbane 1.32/27321/8Brisbane 1.64/28161/16Perth 1.80/2981/32Perth 1.88/3041/64WAN 1.92/3041/64 1.96/27321/8 1.128/251281/2 RD-CSY3021-2008/09

12. BrisbanePerth

13. Please attempt the task on VLSM posted on module web page RD-CSY3021-2008/09