Ethernet Hub - Physical Layer Device

Hub is a network device connects multiple devices and makes single network segment. Hub works in Physical layer of OSI Reference Model. Since it is a layer one device, it does not have the feature to read the signals it transmit. All the devices connected to the hub feel they are connected to the same physical wire. So we can say hub has single collision domain. In other words a hub simply repeat the signal it receives. Let us check the working of hubs.


How Hubs work

When a computer connected to a hub sends packets, hub broadcast the packets to all the ports except the one it came from. Here we can see the difference between Switch and hub. Hub does not read the packets and it broadcast to all ports but Switch is intelligent device and read the packet and just unicast it. So Switch is more efficient compared to hub. Another problem with hub is the higher chances of packet collisions. We know hub has single collision domain and the chances of collision is very high.


Now a days very rarely we use hubs to connect network devices. Most networks use Switches to connect multiple network devices in a single network.

Other Tutorials

  1. Router Cascading Guide

  2. Router and Major Routing Protocols

  3. How to Power Cycle a Router

No:Recent Tutorials
How To Power Cycle a Modem
Setup Linksys WRT54G Wireless Router
3 How to Configure Idea 3G on Android Phone
PING: Transmit failed. General Failure
Solution for Destination Net Unreachable - Error
Destination host unreachable
How to Enable Disabled Adapter
Router Cascading Tutorial
Asianet Dataline Cable Broadband Modem WiFi Connectivity
How to Solve TTL Expired in Transit
Ping Request Could not Find Host
How to Block Websites Using D-Link Router In Home
How To Setup Cisco DPC2320 Cable Modem
How to Setup Reliance DSL Broadband Modem
How to Setup D-Link Wireless Router in to Bridge Mode
How to Setup D-Link Wireless Router Manually
How to find Login IP Address of a Router or Modem
How to Reset a Router Manually
How to Restart WZC

Internet Control Message Protocol (ICMP)

One of the important part we need to do while troubleshooting a network is to check the connectivity of two devices. We have many utilities to check the connectivity and availability of destination device. All these utilities are based on ICMP, defined in RFC 792. Internet Control Message Protocol (ICMP) is used to send error and control information between devices which support TCP/IP. Utilities like ping, tracert, pathping etc works using ICMP. This tutorial explains the functions of Internet Control Message Protocol and the list of error messages generated by ICMP.

Important Functions of ICMP
  1. Send echo requests from a TCP/IP device to another

  2. Responds to Echo request

  3. Helps to find routing path issues

  4. ICMP echo message verify the availability of destination

List of Messages Generated by ICMP
  1. Address Request

  2. Address reply

  3. Destination unreachable

    To learn more about the Destination unreachable message generated by Internet Control Message Protocol, visit the links below.


  4. Subnet Mask Request

  5. Time Exceeded

No: Recent Posts
Network Layer Protocols
Restart WLAN AutoConfig (WLANSVC Service) On Windows 10
Internet Group Management Protocol (IGMP)
How to Setup MTNL Broadband ADSL Modem
Setup Idea 4G on Android Phone
Delete Beneficiary Fund Transfer in HDFC Netbanking
Setup Asianet WiFi Router
Virtual Router Redundancy Protocol (VRRP)
Dynamic Host Configuration Protocol (DHCP)
Remote Procedure Call (RPC)

DMZ In Network Security (Demilitarized Zone)

Now most of the modern Small Office Home Office routers offer DMZ host feature. For those who don't know about the use of DMZ, this tutorial may give an overall idea about it. If you place a device in your network in DMZ, that device won't have much access to other devices connected to the network. Device placed in DMZ is more exposed to external threats as it is logically placed outside the network with limited security. Also all ports of DMZ host are open and exposed to external network. DMZ host has its on merits and demerits.


What is The Use of DMZ in a Network

If you are a hardcore online gamer, you know the hurdles created by the router firewall and NAT. In most cases simple port forwarding allows you to continue online gaming but rarely some users face issues. Ultimate solution for the firewall issues in online gaming is to place your gaming computer in DMZ. However, after this step, your gaming computer is no longer protected by router firewall. Also your computer face limited connection to other computers in your home network.

Technically DMZ host is outside the network. So other hosts in your network is safe even if DMZ host is compromised. Though DMZ computer is compromised by a hacker, attacker will not get access to other devices in the network. So you can run a web service on your computer which can be placed in DMZ without risking the security of other devices in your network.

Further Readings
  1. Denial of Service (DOS) attacks Tutorial

  2. How to Improve The Speed Of Your Internet Connection

  3. Port Forwarding On Belkin Wireless Router

  4. Port Forwarding On Linksys Wireless Router

No: Recent Posts
Broadband Hack Tricks
Network Address Translation( NAT)
What is Smurf Attack & How to Prevent it
How to Setup MTNL Broadband ADSL Modem
Setup Idea 4G on Android Phone
Delete Beneficiary Fund Transfer in HDFC Netbanking
Setup Asianet WiFi Router
Denial of Service (DOS) attacks
View & Clear Saved Username and Passwords In Mozilla Firefox
Setup Log Files for IP Messenger
Make Sure your Computer and Network are Safe and Secure
Omiga Plus Browser Infection Removal Guide
Error 797: A Connection to the Remote Access Server was not Made
How to Reset BSNL WiFi Modem
How to Check Your Tata Photon Plus Internet Usage
Destination Net Unreachable