On 30 Mar 2009, at 16:00, Philip D'Ath wrote:
I've never ran into a case where the "pipes" where so big that QoS was not required. Never.
That's presumably why you have needed to worry about QoS. Buy bigger pipes. :-) If you're constrained (by what the telco will give you, by what you can afford, by what your vendor will support) to pipes that are too small, then sure, it makes sense to concern yourself about which of your customers' packets you are going to give inferior service to in order to let the higher-value packets get the best treatment possible given the inadequate network. If you're not constrained to pipes that are too small, then QoS doesn't buy you much once you've escaped the last mile. What's the serialisation delay of even a 4k jumbo frame on a gigabit ethernet interface? If you can eliminate that tiny jitter by turning on QoS features everywhere, will anybody notice the delay resulting from the end-points' jitter buffers given the codec and propagation latency that's already there? Remember, these are people who think that call quality over GSM is just fine. Might the operational impact of having to manage those QoS features perhaps have more impact on the customer, in the long run? No doubt there are times when adding bandwidth isn't practical, for whatever reason. However, in my experience people who worry about QoS in their core usually have been sold a problem by a vendor, rather than a solution. Joe