Bigbro's foray into the scary world of blogging
Modern networks are converging on an IP transport, with voice, video and data traversing the same networks. This gives us a cost saving and complexity saving, but introduces other problems such as jitter, latency and packet loss. QoS allows 'selective unfairness' to be applied to packets traversing a router - EF (Expedited forwarding), AF (assured forwarding) and BE (Best effort) type classes are generally available. There's no such thing as a free lunch, some traffic is going to have to suffer - and there is often a political or administrative issue in deciding exactly what traffic should be put in each class.
Network monitoring (mrtg, cacti, etc.) gives us some view of how the network is looking, but doesn't give us an indication of what effect micro-bursts and short-lived traffic patterns are having. This is what the Corvil Bandwidth Quality Manager attempts to model. By getting a copy of real traffic (from a span or tap port) and building up a virtual model of the network in software, the system can make some estimates of the expected latency. Not only that, but since it's a virtual model in software, what-if analysis can be performed.
posted at: 16:39 | path: /technical | permanent link to this entry
