Column: Net strain won't ease for two to three years

While the Internet growth continues unchecked, many network hardware companies and ISPs are doing their utmost to ensure adequate bandwidth will be available for businesses attempting to deploy strategic applications over the World Wide Web.

While the Internet growth continues unchecked, many network hardware companies and ISPs are doing their utmost to ensure adequate bandwidth will be available for businesses attempting to deploy strategic applications over the World Wide Web.

It’s increasingly obvious that the Internet’s underlying infrastructure issues, which are fuelling speculation of imminent Internet overload, are going to be with us for the next two to three years. The truth is that though there may be some temporary fixes available to fine-tune routing flows, congestion on the Net is something we are just going to have to put up with in the short term.

One thing that is becoming apparent is that some ISPs are looking at new bandwidth reservation and quality of service (QoS) features to guarantee availability of bandwidth. It will be at least a year, though, before ISPs offer the first of these services, and even then, probably only over their own nets. Inter-ISP bandwidth reservation will probably take longer, as a number of kinks need to be ironed out.

Will these steps help improve conditions on the Internet? Probably. But they fall well short of providing the kind of reliability and continuous availability needed for strategic business applications.

To some, that’s no surprise. The Internet is a connectionless network, which means it cannot do QoS or guarantee bandwidth. To expect the Internet to deliver predictable response times is expecting it to do something it wasn’t designed to do.

It’s also becoming clear the public Internet cannot handle real-time audio and video in its current form, with growing pockets of packet loss across the Internet affecting interactive communications. The growth of voice over the Internet will place an even larger strain on the Net.

Currently, there are a number of ISPs experimenting with IP voice over the Internet, but within the next 18 months demand for voice will force them to offer QoS guarantees and make them commit to oversell ratios to ensure they deliver the performance required by the customer.

As QoS and bandwidth reservation facilities sprout up, the underlying infrastructure of the Net will change, too. You’ll see a lot of ISPs migrating to asynchronous transfer mode (ATM) in the backbone because it is designed to merge voice, video and data.

While ATM seems to be one answer to the problem, there are some people in the industry who don’t believe ATM is a solution. ATM chops data into 53-byte packets, which is inefficient in the event of packet loss. The resulting retransmission will cause scores of ATM cells to be rebroadcast for every packet lost.

What looks to supersede ATM is the development of the Resource Reservation Protocol (RSVP), which will enable IP routers to implement classes of service--somewhat analogous to ATM’s available bit rate, constant bit rate and variable bit rate offerings. The upshot is RSVP allows applications to reserve bandwidth based on varying levels of priority.

Basically, certain types of data are tagged, effectively allowing them to use an Internet “fast-lane”. The software then gives routers and switches on the World Wide Web the ability to detect tags on the data which indicate its priority--a concept which seems to go against the whole egalitarian character of the Net.

RSVP is now nearing completion by the Internet Engineering Task Force and some vendors, including Cisco and MCI, have disclosed plans to use it along with the Weighted Fair Queuing algorithm. Eventually, such moves will guarantee bandwidth allocations and delay characteristics for different data types. This would enable video streams or audio streams, for instance, to secure a higher priority than less time-critical email data.

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