Objective
· Create an IP addressing plan for a small network.
Background / Preparation
In this activity, you will play the role of an onsite installation and support technician from an ISP. A customer has called the ISP complaining of e-mail problems and occasional poor Internet performance. On an earlier site visit, the technician had created diagram of the customer’s existing network shown here.
The ISP is preparing a design for a network upgrade. The interim topology diagram for the proposed network is shown below.
The ISP is preparing a design for a network upgrade. The interim topology diagram for the proposed network is shown below.
Step 1: Analyze the network
a. Referring to the Rough Design Notes, determine the minimum number of hosts that a subnet needs to support the new network design.
1) The largest subnet must be able to support 30 hosts.
2) To support that many hosts, the number of host bits required is 5 bits
b. What is the minimum number of subnets required for the new network design? subnets
c. Can this network be subnetted according to the requirements? bisa
For example: If four subnets are required and the largest subnet has to support 128 hosts, this is a problem, because a subnet in a class C network that has been partitioned four ways can support only 62 hosts.
d. Fill in the blanks to summarize the subnetting requirements of this new network design:
This network requires 2 subnets, each supporting 29 hosts. Therefore, 5host ID bits are reserved for the subnet ID. With those values, this network supports 5 subnets, each subnet having 30 hosts.
Step 2: Calculate the custom subnet mask
Now that the number of subnet ID bits is known, the subnet mask can be calculated. A class C network has a default subnet mask of 24 bits, or 255.255.255.0. What will the custom subnet mask be?
The custom subnet mask for this network will be 255.255.255.224or /27
Step 3: Specify the host IP addresses
Now that the subnet mask is identified, the network addressing scheme can be created. The addressing scheme includes the subnet number, the subnet broadcast address, and the range of IP addresses assignable to hosts.
a. Complete the table showing all the possible subnets for the 192.168.1.0 network.
subnet | Subnet Address | Host IP Address Range | Broadcast Address |
1 | 192.168.1.0 | 192.168.1.1 – 192.168.1.30 | 192.168.1.31 |
2 | 192.168.1.32 | 192.168.1.33 – 192.168.1.62 | 192.168.1.63 |
3 | 192.168.1.64 | 192.168.1.65 – 192.168.1.94 | 192.168.1.95 |
4 | 192.168.1.96 | 192.168.1.97 – 192.168.1.126 | 192.168.1.127 |
5 | 192.168.1.128 | 192.168.1.129 – 192.168.1.158 | 192.168.1.159 |
6 | 192.168.1.160 | 192.168.1.161 – 192.168.1.190 | 192.168.1.191 |
7 | 192.168.1.192 | 192.168.1.193 – 192.168.1.222 | 192.168.1.223 |
8 | 192.168.1.224 | 192.168.1.225 – 192.168.1.224 | 192.168.1.225 |
b. llows: (fill in the table below )
Device | Interface | IP Address | Connect to | IP Address |
1841 | Serial 0/0/0 | 11.11.11.100 | ISP Router | |
Fa 0/0 | 92.168.1.65 | Wired hosts | 192.168.1.66..to..192.168.1.94 | |
Fa 0/1 | 192.168.1.97 | Linksys Internet | ||
Linksys | Internet | 192.168.1.98 | 1841 Fa 0/1 | |
LAN Gateway | 192.168.1.129 | Wireless Hosts | 192.168.1.130 to 192.168.1.158 |
Step 4: Consider other subnetting options
What if there were more than 30 hosts that needed to be supported on either the wired or wireless portion of the network. You could borrow fewer bits, which would create fewer subnets, but each one would support a greater number of hosts per subnet.
a. How many bits would be borrowed to create four subnets? 2 buah bit ( 2^2 = 4 subnets)
b. How many bits would be left for hosts on each subnet? 6 bit
c. What is the maximum number of hosts each subnet could support? 2^6th = 64-2 = 62
d. What would the subnet mask be in dotted decimal and slash number (/#) format? Borrowing 2 bits would create a 255.255.255.192 or /26 subnet mask.
e. If you start with the same 192.168.1.0 network as before and subnet it into four subnets, what would the subnet numbers be ? 192.168.1.0, 192.168.1.64, 192.168.1.128, 192.168.1.192
Step 5: Reflection
a. Does subnetting help reduce the problem of IP address depletion? Explain your answer. Jawab :
ya, sangat membantu mengurangi masalah depletions pada IP address, karena bisa membedakan network identifier dengan host identifier.
b. The Rough Design Notes diagram noted that the wireless subnet would have up to 30 PCs connecting. In pairs or in small groups, discuss whether or not that creates a situation in which IP addresses might get wasted. Does it matter, and why or why not?
sia sia karena proses subnetting yang menghasilkan beberapa subjaringan dengan jumlah host yang sama telah dilakukan, maka aka nada kemungkinan di dalam segmen –segmen jaringan tersebut memiliki alamat – alamat yang tidak digunakan.
c. There are alternate methods of subnetting using CIDR and VLSM. Would VLSM be a worthwhile option for subnetting this network? Discuss in small groups.
vlsm bisa menjadi solusi karena teknik subnetting dengan VLSM dapat dilakukan secara rekrusif : network identifier yang sebelumnya telah disubnetkan, di subnetkan kembali . maka dengan kata lain pengambilan kembali sisa dari bit- bit host.
Lab 4.2.4 Determining PAT Translations
Step 1 : Determine the IP Address of the computer
a. Mengecek Ipconfig pada coment prompt.
b. What is the IP address of the computer? 192.168.1.100
c. Is there a port number shown, ans why or why not? Jawab:
IP address as shown for the active adapter on the computer No port number is shown, because port numbers are related to active connections between processes on multiple devices.
Step 2: determine the IP address of the gateway router or ISR
Check with your instructor to get the IP address for the ISR NAT RouterGateway
Internet Ethernet address:192.168.1.10
External internet address:192.168.2.10
Step3: display baseline netstat result
a. At the command prompt, type the nestat-n command.
b. What type of information does the nestat-n command return? Jawab:
Active Connections information shown: Protocol, Local Address, Foreign Address, State. IP addresses and port numbers are listed
c. Where does the IP address found in step 1 apper ? is there a port number associated with it? Why or why not? Jawab:
The netstat command shows the local IP address in the Local Address column.
Port number may or may not be shown depending on current active connections.
Note: If the computer has been idle for a while and no recent network connections have been made, it may show no entries or only show the loopback address and port numbers in Local and Foreign Address columns (e.g. 127.0.0.1:1039)
Step 4: diplay active network connections
a. Ping www.cissco.com and record the address:
b. Open a web browser and enter www.cisco.com in the addres bar.
c. Go back to the command prompt window. Type the nestat-n command again, an then type the command without the –n option. The output looks similar to the following figure, depending on what other network application and connection are open when you issued the command.
- What is the difference in the output between the nestat and nestat-n commands? Jawab: Without the –n option, IP addresses are resolved to host names, and protocol numbers are converted
to the protocol name.
e. Write down the connection entries for the client IP address of the www.cisco.com web server.
Local client IP address and port number:
Foreign IP address and port number:
f. Are there more nestat entries the second time? Jawab : ya
Step5 : determine translated address
Use the information recorded in step 2 and 4 and topology diagram shown at the beginning of the lab to fill in the address port colums.
Type | IP Address | Port No. | |||
1. Request | Source | Inside-Local | 192.168.1.100 | XX (e.g., 1383) | |
Dest. | Outside-Local | 198.133.219.25 (Cisco) | 80 | ||
2.Translation request | Source | Inside-Local | NAT router public IP | XX (e.g., 1383) | |
Dest. | Outside-Local | 198.133.219.25 (Cisco) | 80 | ||
3. Response | Source | Inside-Local | 98.133.219.25 | YY (will vary) | |
Dest. | Outside-Local | NAT router public IP | XX (e.g. 1383) | ||
4. Translation response | Source | Inside-Local | 198.133.219.25 | YY (will vary) | |
Dest. | Outside-Local | 92.168.1.100 | YY (will vary) | ||
Step 6 : Reflection
a. Port address translation (PAT) is also called NAT with overload. What does the term ‘overload refer to? Jawab: Using a single “overloaded” external address to translate for multiple internal addresses.
- The NAT terminology used in the lab includes four types of address. Inside local. Inside global. Outside local. And outside global. In many connection that pass through NAT routers. Two of these addresses are often the same. Which two of these four address normally reman unchanged. And why do you think that is the case? Jawab:
Outside local and outside global, because the outside or destination IP address must remain the same for an internal host to be able to reach another host on the Internet.
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