March 29, 2011


Broadband Vs Leased line!

There is nothing more to broadband than dial-up except that its digital, while dialup is analog. A positive voltage over the telephone line was a 1 and a negative voltage on the line was a 0. That’s how dialup modems used to work and traditional phone lines couldn’t handle more than 2000 such fluctuations per second, since the line was analog. The analog was then converted to digital, so that the voltage variations were just 0 to 5 or slightly higher and therefore greater frequencies were possible with suitable equipment at the service provider’s end. In a broadband, you don’t need to dial a number, since all lines are always connected to the internet server, and your digital modem does the handshaking automatically as it is booted up, and you still can use the phone when you are connected to the internet, unlike in the old analog dialup system.

Since broadband is digital, the band of data that can be transferred is a bit broader, and nothing more.

The broadband usually shares a very high end leased line. Therefore, a lower bandwidth and a higher bandwidth connection in a broadband just differ in packet size, and not in number of packets. This is proven when you download something from a website or an FTP. If there is only a single source of data, the download appears to be faster. While you download the same thing with a torrent with multiple connections, the efficiency of the download will be rather poor. This is because the broadband cannot handle multiple connections as good as it handles larger packets. If you connect a broadband line with high bandwidth to a network with about 20 PCs, the output efficiency will be very poor. Everything will seem to be lagging.

When you connect a leased line to the same network, you will find a great performance. This is because the leased line can handle more connections while transferring bigger packets. A broadband is just acting as a local network that distributes the data from a super jumbo leased line within its area.

Virtual Leased Lines Using MPLS:

A question that might pop up in the reader’s mind is, why MPLS for VPNs? The answer is quite simple; MPLS seems like an attractive technology for the following reasons. The MPLS Label Switched Paths (LSPs) inherently provide tunneling of traffic from one point to the other. Since MPLS switches packets operate based on their labels, it inherently masks the IP address, and hence, could be used to isolate the IP addresses on the subscriber side from those on the service provider side.

In other words, it wouldn’t matter, then, whether the subscriber is using global or private IP addresses; MPLS is capable of supporting both.

The overhead of MPLS encapsulation is small when compared to other encapsulation technologies.

MPLS labels are only four octets long. The EXP bits in the MPLS shim header could be used to prioritize MPLS frames – a feature that is available in most MPLS implementations today. Traffic engineered Label Switched Paths (LSPs) could be deployed in order to offer multiple service levels to subscribers or to avoid network congestion points.

The MPLS approach allows the creation of highly scalable VPNs.

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