The hosting provider subscribe to a certain amount of bandwidth from the ISPs, eg. 5 Mbps,
and all clients shares that 5 Mbps. When the 5 Mbps gets congested, and the clients get very
slow accesses, the hosting provider may or may not upgrade the bandwidth. If your usage is
excessive, as determined by the provider, your usage is likely to be capped.
Almost all bandwidth on the Internet is shared. However, providers can provide higher priority
to the bandwidth for customers who pays for a higher SLA (Service Level Agreement). This is the
meaning of "guaranteed" in guaranteed bandwidth.
The gold standard in providing bandwidth management is to use Allot Netforcer or Packeteer.
These cost up to SGD 30,000 for 100Mbps shaping, to provide QoS (Quality of Service) guarantees
to each client. There will still be a shared pool of bandwidth, eg. 45 Mbps. Out of this 45 Mbps,
there may be 100 servers. Depending on the bandwidth subscribed by these clients, the hosting
provider can set guaranteed bandwidth, burstable bandwidth, and priority to the bandwidth.
Some providers use DIY bandwidth management, using freebsd.
Some high end application switches, and firewalls also provide bandwidth management;
where there is a setting for guaranteed and burstable bandwidth.
Lower cost providers will use rate limit per port on their switches to provide "guaranteed"
bandwidth. They limit your bandwidth to a certain amount, eg. 2 Mbps, and what you actually get is
zero guaranteed bandwidth, burstable up to 2 Mbps.
There is no true dedicated bandwidth on a Internet wide basis.
Analogy (bandwidth to roads)
Bandwidth subscribed by your provider = size and condition of the road
Clients = vehicles on the road
- Shared - everyone gets to use the road. cars, lorries, buses. If you hog the road, the
Traffic Police stops you. If you hog too often, you will get punished.
- Guaranteed - Bus Lanes, or Motorcade escorted by traffic police, or Parades
- Dedicated - No other vehicle can use the road, even when you are not using it.
example, drive any where within Singapore, and there is no traffic lights, no other vehicle on
the road, any time of the day.
11 Apr 2007