In a few past articles, I’ve described fractional T1 and bonded T1 lines. Another option for those looking for more bandwidth for their business is burstable T1.
First off, burstable T1 gets its name from ‘burstable billing,’ the method of measuring bandwidth based on peak use. This is the most ideal solution for customers requiring very high bandwidth, but in bursts. It involves a full T1 line with all its bandwidth available all the time. The T1 service is sold with a set mount of monthly bandwidth. Measuring technology attached at the ISP’s end measures your bandwidth use, and if you exceed the allotted level of data, you would pay a premium.
The concept developed based on the idea that users use their Internet connections in bursts. When a page loads, bandwidth is sent in a burst and when it’s loaded, the user reads the page and data isn’t being sent or received; hence using the Internet in bursts. Burstable T1 can provide you to ‘burst’ to full T1 speeds of 1.544 Megabits without the cost of an entire T1 connection.
The beauty of a burstable T1 service is that it gives you a cheaper, but full T1 line for your business. Large packets of data can be sent or received quickly, but you don’t need to break the bank to have that availability. Here are some other benefits that a T1 line can give:
Reduced costs for users with fluctuating bandwidth needs or very high bandwidth bursts
Increased sales by improving the interaction time between your customers and your organization via the Internet
A manageable network by enabling usage statistics
Controlled bandwidth costs so you only pay for what you use
This “pay as you go” service can cost about half the price of a full bandwidth T1 line. The major plus of burstable T1 is that the highest 5% of bandwidth usage for each month is “free.” That’s how burstable billing works.
Billing is based on sustained usage levels during the month, as determined by traffic samples taken every five minutes, seven days a week. Your monthly charge is determined by the usage level under which 95% of samples fall. So lets say 95% of the samples taken in a month fall below 6Mbps. Your usage tier would be 0-6 Mbps. That tier would be at a certain rate, but the full bandwidth is still available should you need to use it. Burstable T1 connections are technically more complicated but are very cost effective and give high performance.
Saturday, April 28, 2007
In a few past articles, I’ve described fractional T1 and bonded T1 lines. Another option for those looking for more bandwidth for their business is burstable T1.
Tuesday, April 24, 2007
MPLS… Multi-Protocol Label Switching! Not to be Confused with Minneapolis
MPLS for the speed and efficiency you need.
Multi-Protocol Label Switch, or MPLS, is a standards-approved technology for speeding up network traffic flow and making it easier to manage. It acts the same way as VPN tunneling, in that it encapsulates protocols and data before sending them out in their own tunnels. Sometimes, MPLS is referred to as “Layer 2.5” because it emulates properties of Layer 2 (data link layer i.e. Ethernet) and Layer 3 (networking layer i.e. Internet Protocol, or IP).
MPLS is just a newer way of doing the same work that frame-relay and Asynchronous Transfer Mode (ATM) do. MPLS is becoming more popular because it is better suited for current and future technology needs. In particular, MPLS skips the cell switching and signaling-protocol of ATM. ATM breaks up data into encrypted fixed-sized cells to send out between two end points. MPLS recognizes that small ATM cells are not needed in the core of modern networks, since modern optical networks are so fast (at 10 Gbit/s and well beyond) that even full-length 1500-byte packets don’t suffer any real noticeable real-time delays. Thus, because of the increased bandwidth available, traffic engineering and out-of-band control, which frame relay and ATM became popular for, is still maintained.
MPLS was originally called “Tag Switching” by its developers from Cisco Systems, Inc., and was renamed "Label Switching" when it was handed over to the IETF for open standardization. It was developed to make way for the creation of simple high-speed switches, since it was impossible to forward IP packets in its entirety through hardware for a long period of telecommunications. Recently, advances in VLSI (Very-large-scale integration) have made the hardware possible for such duties, but the systemic advantages of MPLS, such as the ability to support multiple service models, do traffic management, etc., remain.
Instead of encrypting packets, MPLS adds a 32-bit tag to packet headers. MPLS works by pre-pending packets with an MPLS header, containing one or more 'labels'. The packets are called label stacks. Each stack contains four fields: a 20-bit value, a 3-bit field for QoS priority, a 1-bit ‘bottom of stack’ flag (meaning if set, the current label is the last of the stack), and an 8-bit TTYL (time to live) field.
When packets enter an MPLS-based network, Label Edge Routers (LERs) give them a label (identifier). A tag router, the ingress router, will examine the desired destination address, and creates a tag that chooses a virtual circuit or label switch path for that packet. From there on out, tag switches will only look at the tags to determine how to forward the packet. Routers that are performing routing based only on Label Switching are called Label Switch Routers (LSR). There may be multiple routes available for each label switch path so that the tag switches can manage outages, congestion and differentiated services. At the egress point, the exit router, the MPLS tag is removed before sending the packets on their way.
Processing small tags is faster than having to deal with larger headers at each router, creating choke points for data flow. Another advantage of MPLS networks is that it can be designed to provide more bandwidth, or shorter latency paths for voice packets in VoIP telephone systems. Video packets are extremely heavy on bandwidth so it would be best not to funnel them into paths where computers are backing up large databases. Through MPLS networks, voice and video can have the bandwidth needed to maintain quality of service.
When properly designed, deployed, and maintained, MPLS in a private network is a powerful tool to increase business efficiency while reducing costs and improving performance. MPLS networks are now spreading to include access networks.
To set up MPLS or other networking services for your business, check out T1 Stop Shop.
Saturday, April 21, 2007
Circuit Switching vs. Packet Switching
What’s the huge difference anyway?
First off, let me explain switches in general. A switched network goes through a switch instead of a router. Most networks are actually headed toward flat switches on VLANs instead of routers. A router can handle the work of a switch, but much of IT today is going toward flat switched networks. So when we’re talking about circuit switching or packet switching, we are more and more talking about doing it on a switch.
Now in my last two articles, I’ve explained the differences between circuit switching networks and packet switching networks. In principle, circuit switching and packet switching both are used in high-capacity networks. Circuit switching establishes a direct point-to-point connection is made, like in a telephone call. The dedicated line cannot be used by anyone else while it’s already in use by two other users. Packet switching doesn’t require the direct line of contact, and uses any available network connections to route data packets (data, voice, video, etc.) through different routes until it reaches its destination where the packets are reassembled to its original message.
Circuit switching –
1) Ideal when data must be transmitted quickly, arrive in sequencing order, and at a constant arrival rate. Ideally, it is used for transmitting real-time data, such as audio and video.
2) Network resources are static.
3) Dominates the public switched telephone network or PSTN
Packet Switching –
1) More efficient and robust for data that is burst in its nature, and can withstand delays in transmission, such as e-mail messages, and Web pages.
2) Uses communication lines that are not dedicated to passing messages from the source to the destination. Different messages can use the same network resources within the same time period.
3) Dominates data networks like the Internet.
The difference in real-world situations:
Packet switching is acceptable when calling up a web page or downloading a file, since a tiny delay is hardly noticed. These tiny delays are very noticeable with voice, though. This point is really important. Circuit switching guarantees the best sounding call because all packets go in order without delay. Delays in packet switching for voice causes cause voice quality to fall apart, as anyone who has used VoIP can tell you.
Bottom line: circuit switching is more reliable than packet switching. When you have a circuit dedicated for a session, you are sure to get all information across. When you use a circuit which is open for other services, then there is a big possibility of congestion (which is like a traffic jam in a network), and hence the delays or even packet loss. This explains the relatively lower quality of VoIP voice compared to PSTN.
Even so, there are protocols giving a helping hand in making packet-switching techniques to make connections more reliable. An example is the TCP protocol. Since voice is to some extent tolerant to some packet loss, packet switching is ideal for VoIP.
When you are making a PSTN call, you are actually renting the lines. This explains why international calls are expensive. Expensive enough for many people to sacrifice quality for cost efficiency. You pay for each and every minute you spend CONNECTED on a dedicated line. In a conversation, you take turn speaking. Plus, there are those moments where there is silence. Ultimately, you’re only using less than half the time of what you are paying for. With VoIP, you actually can use a network or circuit, even if there are other people using it at the same time. There is no circuit dedication. The cost is shared.
Future of circuit and packet switching for telephony:
Packet switching is getting better with improved VoIP technologies, but it may never replace the dominance of circuit switching in PSTN. Replacing circuit switched switches with packet switches across the country would be a monumental task, requiring billions of dollars over years and years. Plus, lengthy calls over the Internet place huge demands on switches that were never planned for, tying up circuits longer than ever imagined. Change is probably going to come at some point, and the Internet's traffic now motivates engineers to move toward a unified switching method in the PSTN.
While the PSTN creeps towards convergence, many telecom companies are looking at placing calls over packet switched local area networks the Internet. A company with a packet based switch will allow you to eventually store all of your e-mails, pages, faxes, and voice calls on a single computer which also acts as your phone. Convergence would enable us to access all these features. Software, not hardware, would be used to utilize features like conferencing and call forwarding; or even video conferencing if the number dialed at the office is to a computer and not to a desk telephone. The drive toward unified packet switching will enable a brand new future for the public telephone system.
Sunday, April 15, 2007
Packet Switching: Circuit Switching’s Nemesis… Well alternative, but “Nemesis” is more dramatic and funnier to say
Circuit Switching’s Nemesis… Well alternative, but “Nemesis” is more dramatic and funnier to say
Packet switching is a WAN (Wide Area Network) technology of protocols that divide messages/data into packets (units of information carriage), then route them individually to its destination. During the transfer of the packets, the packets can be delivered altogether or independently of each other through different routes. Once at its destination, they are recompiled into the original message.
To prevent unpredictably long delays and ensure that the network has a reliably fast transit time, a maximum length is allowed for each packet. This is why a message would be submitted to the “transport layer” first, and then divided by the “transport protocol” entity into a number of smaller packet units before transmission. The end result is a reassembled message at the destination. This method of transferring data optimizes bandwidth available in a network to minimize the transmission latency (time it takes for data to pass across a network), and to increase the strength of communication.
The costs to customers using packet switching are lower than point-to-point lines because packet switching is more efficient in using a network infrastructure. The carrier can create virtual circuits between customers’ sites through its packet routing protocols. The section of the network that is shared is often referred to as a “cloud.” Packet switching is also called connectionless networking because no physical connections, like circuit switching, are established.
Packet-switched networks using satellite or terrestrial radio as the transmission medium are known as packet satellite or packet radio networks, respectively. These networks were designed for covering large areas for mobile stations, or for applications that benefit from the availability of real-time information at several locations.
Handling messages of different lengths was always done very well by packet switching, as well as different priorities when quality of service (QoS) attributes were included. Packet switching was originally designed for data, but lately packet networks are becoming the norm for voice and video as well.
The most well known use of packet switching is the Internet, which is often referred to as a “Datagram Packet Switching Network.” The first international standard for wide area packet switching networks was X.25. Other examples of packet switching are Ethernet, frame relay, and mobile phone technologies such as GPRS and I-mode.
Already, we can see that there is more flexibility with packet switching than with circuit switching. The Internet, which is a widely used infrastructure, can be used efficiently without the need for a point-to-point connection that circuit-switching networks require.
Come back later this week as I compare circuit switching and packet switching.
Friday, April 13, 2007
Circuit switching is the most common method used to build communication networks in the world. In telecommunications, a circuit-switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. A physical point-to-point path is obtained and dedicated to a single connection between two end-points in the network for the duration of the connection.
Early telephone exchanges are a good example of circuit switching. A caller would have to ask the operator to connect them to the person the caller wanted to reach. This was then done on the same exchange or via an inter-exchange link and another operator. The two parties in the phone call would then be in a physical electrical connection through their telephones for the duration of the call. During that time, no one else can use the physical lines involved, even if no actual communication is taking place in the dedicated circuit, that channel still remains unavailable to other users. Channels that are available for new calls to be set up are said to be idle.
In modern circuit-switched networks, electronic signals pass through several switches before a connection is established. And during a call, no other network traffic can use those switches.
Switched circuits allow data connections that can be initiated when needed and terminated when communication is complete. This works much like a normal telephone line works for voice communication. Integrated Services Digital Network (ISDN) is another good example of circuit switching. When a router has data for a remote site, the switched circuit is initiated with the circuit number of the remote network. In the case of ISDN circuits, the device actually places a call to the telephone number of the remote ISDN circuit. When the two networks are connected and authenticated, they can transfer data.
Circuit switching technology became a necessity for communications equipment that required high quality, real-time data transmission. Circuit switch technology allowed high-speed, low latency, simultaneous connections between mainframes, workstations, servers, and data storage systems.
Since the first days of the telegraph it is possible to multiplex multiple connections over the same physical conductor, Regardless, though, each channel on the multiplexed link was either dedicated to one call at a time, or it was idle between calls. Circuit switching can be relatively inefficient because capacity is wasted on connections, which are set up but are not in continuous use (however momentarily). On the other hand, the connection is immediately available and capacity is guaranteed until the call is disconnected.
I’ll talk about packet switching in the next article, and how it’s seen as a better alternative to circuit switching.
Tuesday, April 10, 2007
Plug in the Computer and Log-on at the Same Time
Broadband over Power Lines Coming Soon (?)
Something I’m sure a lot of people don’t know about is BPL. What is BPL you say? Point proven. BPL is “Broadband over Power Lines. The idea of BPL is that you can plug your computer into any electrical outlet at home and have high-speed Internet immediately. This technology combines the radio, wireless networking, and modem technology to send data over power lines in speeds comparable to DSL and cable (between 500 kb and 300Mbps).
The big upside to having BPL is that rural areas, where access to high-speed Internet is not readily available, can have access to broadband service, simply by tweaking current power grids with specialized equipment. Having access to electricity gives access to broadband Internet! Imagine that.
Right now, there are two types of BPL service: In-house BPL and Access BPL. In-house BPL can network machines at home, like home appliances (i.e. light switches, televisions, sound systems, etc.) Access BPL will carry broadband Internet using power lines and allow power companies to electronically monitor power systems.
BPL would data through the current infrastructure of power lines, so new fiber-optic lines don’t have to be laid out by phone companies. The thing is, fiber-optic lines were very stable and could transmit trillions, yes with a “T”, of bytes of data a day without interfering with other types of transmissions. BPL is based on the concept of bundling radio frequency (RF) with AC (alternating current) to transfer data on the same lines. Electric companies have used this technology for years to monitor the performance of power grids. The infrastructures of these power grids consist of generators, substations, transformers, and everything in between that carries electricity into your home.
An issue with sending radio signals through alternating current is the “noise” of electricity. At high voltages, the “noise” is heard as a humming noise you are all familiar with. At high voltages of electricity spikes in frequency and BPL requires electrical power to maintain a separate frequency than it uses, or data can be damaged or completely lost during transmission. To avoid this problem, BPL providers would skip that part of the electrical infrastructure and move down to the medium-voltage power lines. As it travels through these medium-voltage lines, data can only go so far before degrading, so repeaters would have to be installed along the way to repeat the data in a new transmission for the next stretch of transmission. Once the electricity and data arrives at its destination, your home, it would have to be separated. Repeaters are used to separate the low-voltage data signals to bypass transformers, otherwise data can degrade. The final stretch of the transmission is the signal into your home. Some companies carry the signal directly into your home whereas other companies install wireless devices on poles.
Once inside your home, BPL modems specially designed for pulling data out of an electrical current are plugged into your electrical outlet and into your computer. The BPL modem is PnP, and is the size of a typical power adapter. The wire to your computer is an Ethernet cable. BPL modems also come in wireless models.
BPL technology has been slower to develop in North America. More equipment would have to be installed overall in North America. As said before, repeaters have to be installed on poles to separate the low-voltage data currents, but it’s not uncommon that one distribution transformer is connected to only one house, whereas 10 to 100 homes can be hooked up to the same transformers in Europe. An upside to this is that since bandwidth is limited, users can benefit from increased speeds since fewer homes are sharing the same connection. There are currently a few developers trying to work out the kinks of this technology, but there are issues that are slowing down approval by the FCC and IEEE.
BPL runs into FCC conflicts with radio-frequency emission limits. Since electrical cables are not shielded in shielded cables like on TV, cable TV, and telephone lines, they are clear of interference problems. Power lines have no shielding, and in many cases, the power line is a bare wire. This lack of shielding provides frequency interference. The interfering signals can disrupt air traffic control radios, police radios, and other short-wave radio transmissions. The amount of bandwidth a BPL system can provide CONSISTENTLY compared to cable and wireless is also in question.
If BPL does work out and become standardized, I can only imagine the possibilities of convenience at home. Hooking up your sound system and TV would be a cinch through your electrical “network.” You can sync your alarm clock, light switch, and coffee maker in the morning via broadband. The current citywide Wi-Fi Internet infrastructure being installed in some American cities would be obsolete, or welded into the infrastructure of BPL. Can all this work, or is it wishful thinking? I hope it works because, most importantly, more people that currently don’t have access to high-speed Internet will be able to connect, making our already small world an even smaller one.
*Cue music* It’s a small world after all.
Sunday, April 8, 2007
Create an Online Private Network That’s Secure and Reliable.
Virtual Reality? Not Quite. It’s a Virtual Private Network! YAY!
Not too long ago, companies with users and offices geographically separated had to use intranets (password-protected sites designed for use only by company employees) or leased lines, like ISDN or OC3 fiber, to maintain a Wide Area Network (WAN) for fast and secure digital communication. The growing popularity of the Internet convinced some businesses to turn towards it as way of extending its own networks; in comes VPN. A Virtual Private Network (VPN) is a private communications network used mainly by companies, or other organizations, to securely connect remote sites or users together over a public network (usually the Internet). VPN traffic is carried through an existing networking infrastructure on top of standard protocols, or over a service provider's private network with a defined Service Level Agreement (SLA) between the VPN customer and the VPN service provider.
One common type of VPN, typically used by a large business with hundreds of sales people in the field, is “remote-access” also called a virtual private dial-up network (VPDN). This is a user-to-LAN connection used by a company with employees who need to connect to the private network from various remote locations. If a company needs to set up a large remote-access VPN, they will typically subcontract an enterprise service provider (ESP). The ESP sets up a network access server (NAS), which remote users would reach by dialing a toll-free number. The ESP provides telecommuters with desktop client software for their computer, which is used to access the corporate network. Through the use of a third-party service provider, remote-access VPNs permit secure, encrypted connections between a company’s LAN and remote users.
Another type of VPN is “site-to-site.” A company can connect multiple fixed sites over a public network, such as the Internet, through the use of dedicated equipment and large-scale encryption. There are two kinds of site-to-site VPNs: Intranet-based and Extranet-based. Intranet-based VPN connects remote user(s) to a single private network. Extranet-based VPN is a network that connects business partners LAN to LAN and allows all of the various companies to work in a separate, shared environment.
A well-designed VPN consists of security, reliability, scalability, and integrated network and policy management. These features can improve security, reduce operation costs versus WAN, provide a convenient remote workstations for employees, provide global network opportunities, provide telecommuter support, and provide broadband networking compatibility.
VPN keeps your connection and data secure over the information superhighway, known as the Internet, through the use of firewalls, encryptions, IPSecs, and AAA Servers.
A firewall is the first line of defense between your private network and the Internet. You can restrict the number of open ports, what types of packets are passed through, and which protocols are allowed.
Encryption is the process of taking the data sent from one computer and encoding the data so that when sent, only the receiving computer can decode the information.
Internet Protocol Security Protocol (IPSec) provides enhanced security features like better encryption algorithms, and more comprehensive authentication. IPSec can encrypt data between various devices, such as: router to router, firewall to router, PC to router, and PC to server.
AAA (authentication, authorization, and accounting) servers are used to secure access in a remote-access VPN environment. During the dial-up request by a user to establish a network connection, the AAA server checks who you are (authentication), what you’re allowed to do (authorization), and what you actually do while logged on (accounting). Accounting information is useful for tracking client use for securing auditing, billing, or reporting purposes.
The beauty of VPN over the Internet is its scalability. This is a major advantage over having typical leased lines. Leased lines are direct, and its cost increases proportionately to distances involved between offices. A VPN uses an existing infrastructure, the Internet, to connect members of a network securely and quickly without the cost issues.
Most VPNs rely on tunneling to create a a private network that reaches across the Internet. Tunneling is the transmission of data through a public network in such a way that routing nodes in the public network are unaware that the transmission is part of a private network. Essentially, tunneling places an entire packet within another packet and sends it over a network. The network and both points, called tunnel interfaces, where the packet enters and exits the network, understand the protocol of the outer packet. Tunneling allows the use of public networks (i.e. the Internet), to carry data on behalf of users as though they had access to a 'private network', hence the name “VPN.”
Tunneling requires three different protocols: Carrier protocol, encapsulating protocol, and passenger protocol. To clearly explain what these protocols do, I think it’s best to use an analogy: It’s like mailing a care package sent to a friend through the post office. The post office loads the package (passenger protocol) into a box (encapsulating protocol), which is then put into a postal truck (carrier protocol) at the Post Office (entry tunnel interface). The truck travels the highways (Internet) to your friend’s home (exit tunnel interface), and delivers the package. Your friend opens the box (encapsulating protocol) and removes the package.
Hopefully this article helps you understand VPN a bit. It’s a great way for companies to provide its employees a secure and reliable way to connect from any location. For more information, please visit Nationwide VPN.
Tuesday, April 3, 2007
Bond… Bonded T1.
Before You Upgrade to T3, Take a Look at Your Options
In my previous search for residential T1 lines, I came across the option of bonded T1 technology. Basically, a bonded T1 line is more than one regular T1 line “bonded” or joined together to increase bandwidth speeds. Inverse multiplexing (IMUX) divides traffic from a single bit stream among multiple circuits. This means that traffic from a single source is distributed across the individual circuits to make use of, say, the 3Mb of bandwidth from two bonded lines.
A full T1 line provides approximately 1.5Mbps of broadband speed. You would estimate an additional 1.5Mbps for each extra T1 line in a bonded line, meaning 2 lines equate to 3MB, 3 lines equals 4.5, and so on. With that said, I need to point out that the T1 lines must also run into the same end router, meaning they must run through the same Internet Service Provider (ISP) in order to bond them. Having two lines from different ISPs may load balance the data flow, but it won’t be a true bonded line with exponential results in bandwidth. Plus, not every company offers bonded T1, so snoop around to find out what ISP best suits your needs.
Why have bonded T1? Well it’s always a matter of dollar signs. Most corporations expanding beyond the limits of their T1 service choose to move onto fractional T3 lines, which deliver about 3 to 22 Mbps. Bonded T1 is a viable alternative because the costs are usually cheaper. An ISP I found advertises that their bonded T1 lines are 75% CHEAPER than a fractional T3. Prices vary, but the average price of a fractional T3 line is fixed around $3,500 a month.
Let me provide a charge of bonded T1 pricing:
# of T1 Lines Bonded
A T3 line would cost about $4600 a month, and $3,500 for 10Mb Fractional T3.
Bonded T1 lines are redundant, meaning if any lines fail at the moment, the data will be piped through the other lines in the bonded line to provide consistent data flow.
The maximum of lines bonded is usually around 4 T1s, although some have gone as far as 8. However, if you go beyond 4 bonded T1's it makes much more sense to start looking at a fractional/burstable DS3. Take into consideration that 8 bonded T1s would get you about 12Mbps. Those of you who need heavy-duty bandwidth should seriously consider getting a T3 line, which provides 45Mbps worth of speed.
Corporations who jump from a dual bonded T1 speed to a 6 Mbps T3 will typically incur a larger monthly price than that of just adding more T1s. The draw to T3 is found in its scalability properties. Upgrades are a matter of resizing the port, which will rarely take more than a few days, and the T3 line can go up to 45 Mbps. As users scale above 9 Mbps, the T3 begins to become the better-priced option.
Hopefully this helps those of you out there who are looking for more than a regular T1 can offer, but something cheaper than a T3. It’s really up to what you think your company needs.