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 problem that I have seen is that while you can make certain that a good effort is made to ensure that your high proirity traffic is transmitted before your best effort traffic, you have no real way to ensure that the high priority arrives at the destination in the same manner that it was transmitted. I'm talking about packet order, jitter, and latency. Sure, it will probably get there, but will the data still be worth anything. For Internet traffic, QoS/CoS is probably not worth it, as there is no way to realistically do either across two or more network providers. The real need will be on single provider wishing to sell more than just Internet across their expensive backbone. Such applications will be Toll-quality voice, production/broadcast-quality video, VPN, etc. The way I have seen it, either IP QoS will have to become a reality, or the applications themselves will need to change to handle the poor CoS substitute that is offered now. UK --- Opinions in this email are the personal opinions of the author and are not associated with author's employer. This email account is a not the regular email account of the author and is being used for the protection of the employer. --- Original Message --- Most competitive vendors now provide native and upgrade provisions for QoS in one form or another. The problems most often encountered revolve around multi-vendor cos/qos feature implementation incompatibilities. The "least common denominator features" that are needed for basic interworking usually do not extend to 'differentiating' features that vendors like to hold close to the vest, such as prioritization and cos/qos features. Not without much grief, in any event. It forces one to seriously consider single vendor solutions. fwiw. _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com
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.
participants (2)
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Pete Kruckenberg -
Ukyo Kuonji