Archive for the ‘Network’ Category
TCP/IP architecture model
1. Network interface(Data link) layer
2. Network layer
3. Transport layer
4. Application layer
Network interface layer
The lowest layer of the TCP/IP model. Its task is to provide access to the transmission physical medium and it differs according to the implementation of the medium.
Network layer
The network layer provides network addressing, routing and datagram transmission. Used protocols that will be of interest further regarding DHCP are IP and ARP.
IP protocol
It is the basic protocol of the network layer and in general the internet as a whole. It sends datagrams, which are independent units that contain information about the destination, source and the sequence number of the datagram. The sequence number is used for message reconstruction, since the delivery order of the datagrams might not be the same as their order in the message and delivery reliability isn’t guaranteed at all.
IP protocol versions:
” IP v4 – 32 bit addresses. Provides approximately 4 billion unique addresses which aren’t sufficient at present times.
” IP v6 – 128 bit addresses. The transition to v6 will bring (is bringing) higher security, QoS, packet segmentation and many more IP addresses. (the transition from IP v4 to IP v6 must be supported by the system provider)
Six Largest Mistakes Made when Hiring a Cabling Contractor
Cabling of data and voice systems is often ignored by many companies until the last minute just before relocation or new building takes place. Many information systems professionals view it as a low priority or something that just takes away from their budget for real network components such as servers or software. However having a state of the art easy to manage cabling system is just as important as good reliable servers on a network. Cabling is the backbone of any computer network; it ties all the components of the network together therefore it should receive as much careful consideration as any other network component.
Mistake number one – Blindly choosing the lowest bidder
This is the most common mistake made when installing voice and data network cabling. Often the lowest bidder is the contractor who is the smallest, has the least experience or the one that made a mistake on their bid. Prior to making this decision you should know your contractor. Find out how long they have been in business, visit some of the large installations they have done and by all means go visit their offices and warehouse. A site visit to their office will tell you most of what you need to know about an organization. Make sure your contractor has completed jobs of similar scope and size.
Mistake number two – Choosing the manufactures product that will be installed
Many companies have tried to standardize on a particular manufacture of cabling system. Some of the larger manufactures are Belden, Comscope, Ortronics, AMP and Leviton. You can’t go wrong with any of these big names. However IT managers and corporate executives get hung up on trying to standardize because they believe it will make things easier for the IT staff. The reality of the situation is that if you choose any of the larger names the only components that might not be interchangeable are the faceplates. Of course there are performance criteria as well and they all claim to be the best. Do your own research and choose a manufacture that you feel has a strong company that will be there to stand behind their product should you even need to make a warranty claim
Mistake number three – Paying too much for the latest cabling technologies
The fact is that today’s network components and network components of the future cannot exceed the specifications of Cat 5E and Cat 6 cabling components. Combine this with the fact that the average company moves every 3 to 4 years. You will find it hard to benefit from future proofing a building you don’t occupy. Look at you current infrastructure, what equipment or applications do you plan to add or upgrade? Is Gigabit or 10 Gigabit Ethernet an option for you in the near future?
Mistake number four – Not using universal wiring
The EIA/TIA and BICSI both recommend a universal wiring platform for your Communications Infrastructure. In the old days the average install would consist of a single voice grade cable for the phone system and a single data grade cable (Cat 3, Cat5, Cat5E or Cat 6) for their computers. This of course dedicates the usability of these cables to one system type. This is further exacerbated by the termination method used. Voice cables were traditionally terminated on 66 style blocks (66m1-50), which are not user friendly and require a special tool and cross connect wire to make changes. Telephony companies have made a killing for years just performing MAC work (Moves, Adds and Changes) because a customer was unable or unwilling to brave the telephone closet and perform the MAC work themselves.
The practice of using a true universal wiring platform is now the standard for all reputable cabling contractors. A Universal Wiring Platform is made up of all data grade components that are downward compatible for all voice applications. A common installation would consist of 3 Category 5E or Category 6 cables all terminated on a 110 type Patch Panel. At the wall plate all cable would be terminated on the matching grade of 8 position modular jack (incorrectly know as an RJ-45). This design not only allows for maximum flexibility were the customer could have 3 computers or 3 phones or 2 computer and 1 phone or any configuration that works for their application. The point is that now the customer is in complete control of their cabling infrastructure and does not need to pay a contractor to come out every time they move an office. In the long run this will also save you money on the overall cabling system as it will shift and flex to meet your needs without having to bring in your cabling contractor. Remember, having the contractor in after construction has completed will involve them pulling out ceiling tiles and standing on desks while you are trying to do business. The elimination of the disruption alone makes it worth while.
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Setting Up and Securing Your Wireless Network
There are more and more individuals opting to work from home than ever before. The advantages to this are many including avoiding the morning and evening rush hours, being able to spend time with your kids and significant other, and doing everything on your own time. Though the pitfalls are many, the one that I will be focusing on in this article is that of setting up a secure wireless network for your home based business. Right now somewhere out there, there is someone with a receiver waiting to pick up on an unsuspecting person’s wireless local area network. Their hope is to garner some sensitive information that may lead to identity theft, and stolen proprietary business information.
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Router – Transmitting Packets
In a previous article we discussed the basics of what a router did. We’re now going to get into a more detailed, and yes technical, explanation of how packets are transmitted as well as a few other tech specs of how routers work. So put on your learning caps because you’re in for a real mind bender.
Internet data, whether it be in the form of a web page, a downloaded file or an email message, travels over what is called a packet switching network. Basically what happens is that the data is broken up into individual packets because there is only so much data that can be transmitted at one time. Each packet is about 1500 bytes long. Each packet contains quite a bit of information including the sender’s address, the receiver’s address and of course the information being sent which includes the order of each packet how it should be put back together so that the end user can make sense of the data. The packet is sent off to its destination based on what the router believes to be the best route to follow, which is usually the route with the least amount of traffic and if possible, the shortest route. Each packet may actually given a different route depending on conditions at the time, which in a high traffic network can change every second. By doing this, the router can balance the load across the network so that no one segment gets overloaded. Also, if there is a problem with one piece of equipment in the network, the router can bypass this piece of equipment and send the packet along another route. This way if there is a problem, the entire message will still arrive intact.
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