On Tue, 29 May 2001, Ukyo Kuonji wrote:
The problem is, while most vendors support tagging and priority queuing, non of the current vendors can support true end to end QoS. Instead, we have taken to calling their options CoS.
The elusive "end-to-end QoS" seems to be a network management issue, motivated primarily by the number of knobs (and some featuritis) and lack of QoS best-practice (because there's just not a lot of QoS practice, period). Simple end-to-end technologies (TOS, DiffServ) are enough to handle congestion-management QoS strategies (and some differentiated services), are interoperable across most vendors, and are supported in most edge- and core-class devices. Beyond simple QoS schemes, the complexity mandates an end-to-end management tool. I suspect the cost/benefit curve gets pretty flat above a simple QoS strategy, and anything more complex has diminishing marginal value. Any studies been done on cost/benefit of QoS, it'd be interesting to see where the technical/business case is compelling and where it makes no sense. Pete.