This is a short presentation of Network Architecture that addresses issues such as Network Topology, Subnetting, DHCP server, OSPF Routing Protocol and NAT configurations.

1. ITU-CSU08102: NETWORK ARCHITECTURE,
GROUP ASSIGNMENT.
NO NAME REGISTRATION NUMBER
1. FRANK C. MOYO IMC/BIT/2011325
2. MICHAEL MANYONYI IMC/BIT/2122071
3. JACOB F. KISHENYI IMC/BIT/2123086
4. LUGANO J. ANTHONY IMC/BIT/2122601
5. DADY M. KATIKIRO IMC/BIT/2120188

2. NETWORK TOPOLOGY.

3. SUBNETTING.
• For serial links, we have to ensure that we have two hosts and we are provided with the network
address of 10.10.30.0/24 which means that we will get 256 Host addresses but we are required to
do subnetting so as to get an Ip-address of 10.10.30.0/30 which gives us 4 Host address.
• For the link between the IFM private network and ISP, we are required to use the IP network of
206.107.110.4/30.
Subnet
Number
Network Address First Host Address Last Host Address Broadcast Address
1st 10.10.30.0/30 10.10.30.1/30 10.10.30.2/30 10.10.30.3/30
2nd 10.10.30.4/30 10.10.30.5/30 10.10.30.6/30 10.10.30.7/30
3rd 10.10.30.8/30 10.10.30.9/30 10.10.30.10/30 10.10.30.11/30
4th 10.10.30.12/30 10.10.30.13/30 10.10.30.14/30 10.10.30.15/30
5th 10.10.30.16/30 10.10.30.17/30 10.10.30.18/30 10.10.30.19/30
Subnet
Number
Network Address First Host Address Last Host Address Broadcast Address
1st 206.107.110.4/30 206.107.110.5/30 206.107.110.6/30 206.107.110.7/30

4. For Ethernet links, we have to ensure that we have twenty-five hosts in each
subnetwork and we are provided with the network address of 192.168.200.0/24
which means that we will get 256 Host addresses, but we are required to do
subnetting so as to get an Ip-address of 192.168.200.0/27 which gives us 25
Host address.
Subnet
Number
Network Address First Host Address Last Host Address Broadcast Address
1st 192.168.200.0/27 192.168.200.1/27 192.168.200.30/27 192.168.200.31/27
2nd 192.168.200.32/27 192.168.200.33/27 192.168.200.62/27 192.168.200.63/27
3rd 192.168.200.64/27 192.168.200.65/27 192.168.200.94/27 192.168.200.95/27
4th 192.168.200.96/27 192.168.200.97/27 192.168.200.126/27 192.168.200.127/27
5th 192.168.200.128/27 192.168.200.129/27 192.168.200.158/27 192.168.200.159/27
6th 192.168.200.160/27 192.168.200.161/27 192.168.200.190/27 192.168.200.191/27
7th 192.168.200.192/27 192.168.200.193/27 192.168.200.222/27 192.168.200.223/27
8th 192.168.200.224/27 192.168.200.225/27 192.168.200.254/27 192.168.200.255/27

5. DHCP SERVER CONFIGURATION.
• The configuration has been done in the DHCP Server, that we configured seven pools from the
private network addresses of 192.168.200.0/24 where we performed subnetting and gave it a subnet
mask of /27(255.255.255.224) so as to have 8 subnets that would satisfy the 7 pools configuration.
(where by each subnet has 25 hosts). Server’s IP Configuraions; IP Address: 192.168.200.34,
Default Gateway: 192.168.200.33, Subnet Mask: 255.255.255.224
• Dhcp Relay Agent On Router Configuration. Here we configured the routers as agents of the
DHCP server by running Router(config-if)#ip helper-address 192.168.200.34 on each interface
connect to our private network;
Pool Name Default Gateway DNS Server Start IP Address Subnet
Mask
Max
User
POOL 1 192.168.200.33 0.0.0.0 192.168.200.39 255.255.255.224 20
POOL 2 192.168.200.1 0.0.0.0 192.168.200.2 255.255.255.224 25
POOL 3 192.168.200.65 0.0.0.0 192.168.200.66 255.255.255.224 25
POOL 4 192.168.200.97 0.0.0.0 192.168.200.98 255.255.255.224 25
POOL 5 192.168.200.129 0.0.0.0 192.168.200.130 255.255.255.224 25
POOL 6 192.168.200.161 0.0.0.0 192.168.200.162 255.255.255.224 25
POOL 7 192.168.200.193 0.0.0.0 192.168.200.194 255.255.255.224 25

6. OSPF CONFIGURATION.
• We run the below command to configure the ospf dynamic routing protocol on each router on our private network;
Router A (config) #router ospf <process-id>
Router A (config-router) #network <network address> <wildcard mask> area <area number>
• Verification of OSPF configurations;
Router>
Router>en
Router#show ip route
Gateway of last resort is 206.107.110.6 to network 0.0.0.0
10.0.0.0/30 is subnetted, 6 subnets
O 10.10.30.0 [110/128] via 10.10.30.14, 00:03:05, Serial5/0
O 10.10.30.4 [110/128] via 10.10.30.14, 00:03:05, Serial5/0
O 10.10.30.8 [110/192] via 10.10.30.14, 00:02:50, Serial5/0
C 10.10.30.12 is directly connected, Serial5/0
O 10.10.30.16 [110/192] via 10.10.30.14, 00:02:50, Serial5/0
O 10.10.30.20 [110/192] via 10.10.30.14, 00:02:50, Serial5/0
100.0.0.0/24 is subnetted, 1 subnets
S 100.100.100.0 [1/0] via 206.107.110.6
192.168.200.0/27 is subnetted, 7 subnets
C 192.168.200.0 is directly connected, FastEthernet0/0
C 192.168.200.32 is directly connected, FastEthernet1/0
C 192.168.200.64 is directly connected, FastEthernet2/0
O 192.168.200.96 [110/193] via 10.10.30.14, 00:02:50, Serial5/0
O 192.168.200.128 [110/193] via 10.10.30.14, 00:02:50, Serial5/0
O 192.168.200.160 [110/193] via 10.10.30.14, 00:02:50, Serial5/0
O 192.168.200.192 [110/193] via 10.10.30.14, 00:02:50, Serial5/0
206.107.110.0/30 is subnetted, 1 subnets
C 206.107.110.4 is directly connected, Serial3/0
S* 0.0.0.0/0 [1/0] via 206.107.110.6

7. PAT CONFIGURATION (NAToverload).
• We first added another router to our topology that would link to the ISP for Internet Service. Its IP configuration was as follows;
IP Address: 206.107.110.6 with Subnet Mask: 255.255.255.252 Then we perform the necessary NAT configurations.
• After that we had to ensure that our router on the private network can communicate with the router on the public network for
proper translations. We did so by configuring the public network as a default route (Gateway of Last Resort). This will the allow
other routers on the private network to use this route when there is no specific route on their routing tables for the destination IP
address of a packet. Thus, will aid in efficient traffic forwarding.
• On the NAT router we run the following commands;
• Router>en
• Router#conf t
• Enter configuration commands, one per line. End with CNTL/Z.
• Router(config)#ip route 0.0.0.0 0.0.0.0 206.107.110.6

8. As we used OSPF dynamic routing protocol;
Router(config)#router ospf 1
Router(config-router)#default-information originate
(This informs the other routers in the OSPF domain that this route can be used as a
default route.)
On the other routers on our private network;
Router(config)#router ospf 1
Router(config-router)#redistribute static subnets
(This is used to share routes learned by one routing protocol with another routing
protocol. On our topology being the default route and the OSPF)

9. Verfication of Packet Forwarding;
Pinging 206.107.110.6 with 32 bytes of data:
Reply from 206.107.110.6: bytes=32 time=15ms TTL=251
Reply from 206.107.110.6: bytes=32 time=31ms TTL=251
Reply from 206.107.110.6: bytes=32 time=30ms TTL=251
Reply from 206.107.110.6: bytes=32 time=14ms TTL=251
Ping statistics for 206.107.110.6:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 14ms, Maximum = 31ms, Average = 22ms
Verification of NAT Translation;
Router#show ip nat translations
Pro Inside global Inside local Outside local Outside global
icmp 206.107.110.5:1 192.168.200.66:1 206.107.110.6:1 206.107.110.6:1
icmp 206.107.110.5:2 192.168.200.66:2 206.107.110.6:2 206.107.110.6:2
icmp 206.107.110.5:3 192.168.200.66:3 206.107.110.6:3 206.107.110.6:3
icmp 206.107.110.5:4 192.168.200.66:4 206.107.110.6:4 206.107.110.6:4