Tag Archives: networking

networking is one of IT field that relates system administrator with its jobs, all about network.

Four Main Function Of A Router

Four Main Function Of A Router
Here’s short lists of basic networking element :

Hub Function
1. Connecting computer with other computer in Broadcast Domain

Main Function of Switch
1. Break Collision Domain
2. Same Broadcast Domain

Four Main Function Of A Router
1. Packet Switching
2. Packet Filtering
3. Internetworking
4. Path Selection

Tier 1 ISP Characteristic

Tier 1 network terms is usually used when we talk about computer networking, from meriam webster dictionary the definition of tier is :
a : a row, rank, or layer of articles; especially : one of two or more rows, levels, or ranks arranged one above another
b : a group of political or geographic divisions that form a row across the map (the southern tier of states)

this is taken from http://www.merriam-webster.com/dictionary/tier

Tier 1 network can be understood as rank 1 network, Tier 1 ISP then refers to Rank 1 ISP. from wikipedia the tier 1 network is an internet protocol network that participate in the internet via settlement-free interconnection called settlement free peering.

Tier 2 network / ISP is network that still needs tier 1 ISP reach some portion of (global) internet. This tier 2 ISP pays for unequal traffic flows between them, the term fee-based peering or transit is usually used to refers to this kind of settlement. Tier 2 network may connected through same size network with settlement free peering (tier 2 to tier 2)

While Tier 3 network / ISP is network that is connected to global internet through Tier 2 ISP. as the customer of bigger ISP, they pay for the transit fee to its Tier 1 or Tier 2 ISP.

You can observe the network hierarki from this image

Tier Network Hierarchy
Tier Network Hierarchy

Network Provider Hierarchy

From IDC White Paper (Tier 1 ISPs : What Are They And Why They Are Important) there are some characteristics that represent Tier 1 Network :

1. Tier 1 Networks Dont Pay for the trafic between similiar size networks
2. Tier 1 Networks Have access to all routing tables from their peering networks
3. Tier 1 Networks peer on one or more continent
4. Tier 1 Networks own or lease transoceanic fiberoptic transport
5. Tier 1 Networks deliver packet to and from customer and to and from peers around the world


in computer networks, peering means voluntary interconnection between separately internet network in purpose for exchange traffic between the customer of each network. Each participant doesn’t pay for the traffic, instead they get the money from their own customer. The term peering is used when two participant shared the same link with same size (equivalent sized partner).

The biggest internet provider that connected accross continent is example of tier 1 ISP. some of them will have underground oceanic backbone to ensure it can deliver the highest data rate.

There are 3 basic form of interconnection rules : public peering, private peering, and transit.

private peering refers to direct interconnection between two ISP. this connection is built via layer 1 and layer 2 link between ISP with similar networks capacity and traffic level. Its exclusive and expensive

public peering refers to multiple interconnection of network through internet exchange. it is the predominant model for exchanging traffic between ISP. The term public implies that many tier 1 or tier 2 networks can connect through it. The service itself can be free and commercial. the commercial one tough, tries to give the experience equal with private peering, they move incredible amount of traffic, without loss.

Transit refers to selling dedicated access through ISP network via private lease-line telecommunications circuits. Transit cost comes from circuit cost and variable cost associated with the traffic carried upstream to the internet.

You can read more about it here

TCP/IP Protocol Suite and OSI Model (Protocol Mapping)

TCP/IP protocol suite can be modelled related to OSI. Instead seven layer of OSI, in TCP/IP protocol suite (DoD: Department of Defense), it only has four layers.

DoD and OSI Model
DoD and OSI Model

1. Proces/Application layer in TCP/IP or DoD model integrates the functions of Application, Presentation, and Session Layer of OSI model : node-to-node communication and control of user-interface.

2. Host-to-Host layer in TCP/IP or DoD model represents the functions of Transport Layer of OSI model : transmission service, reliable communication, ensuring error-free delivery of data.

3. Internet Layer in TCP/IP or DoD model  represents the functions of Network Layer of OSI model : logical transmission, IP addressing, routing packets across different network.

4. Network Access Layer in TCP/IP or DoD model represents the functions of  Data Link Layer + Physical Layer of OSI model : monitors data exchange between host and network, hardware addressing, defines protocol for the physical transmission of data.

TCP/IP protocol suite in DoD model.

TCP/IP Protocol Suite in DoD Model
TCP/IP Protocol Suite in DoD Model

Process/Application Layer

1.  Telnet : Terminal Emulation, Allows machine (telnet client) to access resources of other (remote) machines (telnet servers).
2. FTP : File Transfer Protocol, Allows user to transfer transfer file between any machines using it. Protocol + Program (Allow user to do performs certain task by hand).
3. TFTP : Trivial File Transfer Protocol, simple version of FTP, reduced functions and security, but faster than FTP.
4. NFS : Network File System, Protocol specializing in File Sharing, allows different types of file systems to interoperate. Ex : NSF server running in NT server and client in unix allows user to access same file with their normal file system in normal way.
5. SMTP : Simple Mail Transfer Protocol handles email, uses spoole or queued, model of mail delivery.
6. LPD : Line Printer Daemon, Printer Sharing
7. X-Window : Client server operation, Display things trough window server on another computer .
8. SNMP : Simple Network Management Protocol collects and manipulates valuable network information.
9. DNS : Domain Name Service, resolves hostname, changes IP address into hostname and hostname into IP address.
10. DHCP : Dynamic Host Configuration Protocol assigns IP addresses to host. BootP : hardware address must be inputted manually in BootP table. DHCP Provides Information : IP address, Subnet Mask, Gateway address, DNS server, Domain Name, WINS information. using UDP to send broadcast message on FF:FF:FF:FF:FF:FF and

Host-to-Host Layer

TCP ( Transmission Control Protocol )
takes information from application and breaks them into segments, numbers and sequences segments, so that segments can be putted back together in order.

UDP ( User Datagram Protocol )
unreliable protocol, only break information into segments but doesn’t number/sequences the segments, then send it off to destination without any acknowledgement.

TCP and UDP Comparison
TCP and UDP Comparison

Internet Layer

1. IP : Internet Protocol = Internet Layer. it looks each address, using the table, choose the best path to deliver packets.
2. ICMP : Internet Control Message Protocol, provides information about network problems : Destination Unreachable, Buffer Full, Hops, Ping, Traceroute.
3. ARP : Address Resolution Protocol : finds hardware address of known host ip address.
4. RARP : Reverse Address Resolution Protocol : resolves MAC address to ip address.
5. Proxy ARP : Helps Machine reach destination without configuring routing or default gateway.

source : CCNA Study Guide Exam

Block Program Through Windows Firewall

use your firewall to block all exe files in the game’s intsall directory from going online.
blocking program to access internet can be done by setting in windows 7 firewall. Step by step to block program using windows 7 firewall :

1. Open start, write firewall in search program and files

block exe program with firewall
block exe program with firewall

2. Choose allow a program through windows firewall.
3. In new window that appear choose ‘Change Setting’ to enable you to edit firewall rules for each program.

allow program through windows firewall
list of allowed program through windows firewall

4. Find program names that you want to block, for example Pro Evolution Soccer
if you want to block the program from accessing the internet, make sure the check box is empty.

if you fill the check box before program names, it means you allow this program to access the internet. Removing the check in the check box before the program name means you block/disallow this program to access the internet.

Setting Ad hoc network (Peer to Peer) Windows 7

This is step by step to create an adhoc network or peer to peer using wifi on windows 7. ad hoc networks can be useful in general for sharing needs, ranging from sharing files and media, to Internet sharing. In addition these networks typically also used to play online games locally.

needed to make this network a computer or more, to make it follow the steps below:

1. In windows 7 open> Control Panel and select Network and Internet and then select Network and Sharing Center
2. Choose Setup New Connection or Network, then the menu that contains connection options provided windows 7 will appear, from the menus there select setup a wireless ad hoc basis.
3. After selecting the menu appear on wireless ad hoc explanation, click next
4. Next comes form that must be filled in. Those are the Network Name: Type Security, and Security Key;
enter the required information

for example Network Name: HpmeAdhoc, Security Type: WPA2-Personal, Security Key: 12345678,

save of this network part is used if you want to save ad hoc configuration, so that if restart the computer we dont need to perform the steps from 1 to 3.
5. When finished filling click Next.
Continue reading Setting Ad hoc network (Peer to Peer) Windows 7

Internet Model – Protocol Mapping

internet end-user or we can refer to common user normally doesn’t care about how internet works. what they really want is just internet access. what they now consider maybe just speed of their internet connection and amount data transfer quota they have. but sometime knowledge about how internet works is needed. for example to explain view questions about how to check whether or not out connection work, how to solve our miss-configuration settings, etc.

Internet model can serve as guide to answer these questions. internet model comes up with protocol classification. once you know where your need is in the internet model, it will be easier for you to determine the problem and solve or at least know why the problem happened.

these are how internet models map their protocols. there are 2 internet models, OSI and TCP/IP. what we use today is actually TCP/IP model, but OSI model can somewhat help us to understand the ideal internet model.

TCP/IP model
protocol mapping on TCP/IP model
OSI model
OSI model

you can go to these wikipedia pages to learn mode about them :

VLAN Tagging Switch HP Procurve

LAN Select the VLAN to configure.
Tag / Untag / Exclude All. For a port or trunk to participate in a VLAN, its tagging policy must be defined. By default, all ports and trunks are configured as untagged members of VLAN1, and are excluded from all other newly created VLANs.
You can use the Tag / Untag / Exclude All box to configure all ports at once. Click this box until the appropriate options displays:

E — exclude all ports from this VLAN.
T — participate in the selected VLAN and tag all frames.
U — participate in the selected VLAN and leave all outgoing frames untagged. Each port can have only one untagged VLAN membership. If a port is an untagged member of a VLAN and a second VLAN is selected for untagged membership, then the first VLAN membership is automatically changed to E (Exclude).
Then, you can use the Port boxes to refine the ports participation and tagging settings.

Step by Step to Check Your Internet Connection

After u make sure u have turned on your network interface such as wifi or plugged in your LAN cables, there is some steps u could do to determine whether you get internet access or not:

1. ping localhost, if it doesnt work, then maybe your (pc/laptop) network service is disabled. on windows u can enable it in start > control panel > netwrok connection

2. on windows, chech for logo internet connection, if this icon is clear, it means u are connected to internet. if not, maybe you’re just connected to Local Area Network.

3. on windows use ipconfig command. run > cmd > ipconfig , to see your ip adress. if you see 169.xxx.xxx.xxx as your internet address, it’s default address of microsoft interface, it means your computer didnt get dhcp address. probably thera to many users using internet connection near you. on linux use ifconfig command

4. if you know your gateway address, try to ping it.

5. ping internet familiar (unblocked) address such as google or its (easy to remember) dns address , if this works then u can make sure now u can access internet.

Setting Static IP Address in Ubuntu / Backtrack

As laptop user, we may find that we usually connect to the internet using wifi, modem, or lan cable in public rooms, we usually get an IP address from dhcp, so that we dont need to configure manually our interface address. In some occasion, for example if we want to set our ubuntu to work as a server or to be kept in permanent place we need to set its IP address to static IP.

it can be done by modifiing /etc/network/interfaces file.
for default configuration this will display these lines
(eth0 for lan card
wlan0 for wirelesscard)

auto eth0
iface eth0 inet dhcp

by basic understanding for TCP/IP
u can change it to static configuration by doing this step :
1. Edit /etc/network/interfaces file

#rootbt: nano /etc/network/interfaces

2. Change the default example to these lines

auto eth0
iface eth0 inet static

3. Save edited file by pressing Ctrl+O
4. Restart Network just to make it sure it works
#rootbt: ifconfig eth0 down
#rootbt: ifconfig eth0 up
#rootbt: /etc/init.d/networking restart

its just example, u need to change all the number according to your own setting, ask your system administrator if you dont have any information about IP address allocation on your workplace.

How Network Switch Work

Switch is one of many networking hardware that is usually used, but as a customer we rarely see it. It is system administrator’s job to maintain this thing works well as infrastructure support. When we see wireless access point, or see LAN cables, and if we try to follow where the cable ends, we usually will meet this thing. A Box with some RJ-45 slots available, and some indicator lamps on.

Switch, generally works in layer 2, or Data Link Layer, has main function to connect some computers and enable each computer to communicate each other by sending frames. Our internet day today, works with protocol called TCP/IP, rely on this thing to build safer networks. Unlike hub, switch sends each packet to specific destination, so that other destination can not know/see/hear this frame. Using configured switch we can also build virtual lan, or simply lan based on ports. These two things are some major advantages of switch over hub.

To do this “send to specific destination”, swich has built in table that stored “port name” and “specific address” for each port. for example
1 port 1 : freds computer
2 port 2 : brian computer

We can explain how swicth work in this way :

1. first time swicth received frame, it first records the sender address and stored its address and the port in it. then swicth will forward this frame by flooding all ports except the port where the frame came.
2. swicth will wait for the respond from computer with the destination address. when it responds the frame. switch will records the responding computer address and the port where the respond comes.
3. when there is another packet from and to known address and port (has been stored).
it will use the table to send the frame to its special direction
4. if the address hasnt been stored it will do step 1.