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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Question about propagation and queuing delays
On 22-Aug-2005, at 11:14, David Hagel wrote: Most networks I have touched that have seen fit to deploy some kind of "quality of service" mechanism have done so in order to deliberately degrade service in inverse proportion to what people are prepared to spend. This is somewhat contrary to the marketing message, since "pay us more money and we'll wreck your performance less!" is unlikely to win awards as a slogan, but it happens nonetheless.This is interesting. This may sound like a naive question. But if queuing delays are so insignificant in comparison to other fixed delay components then what does it say about the usefulness of all the extensive techniques for queue management and congestion control (including TCP congestion control, RED and so forth) in the context of today's backbone networks? Any thoughts? What do the people out there in the field observe? Are all the congestion control researchers out of touch with reality? Examples are DSL users who are rate-limited down to modem speeds after their leeching budget for the month has been exhausted, and gigabit-attached customers whose traffic is squeezed as it is carried over expensive bits of network (e.g. bits that cross oceans). These may be more common in regions with expensive external paths that are used by a high proportion of traffic (e.g. small, English-speaking countries in the Pacific rim) than it is in North America. In North America, the usual contention I have seen in backbones is a lack of external capacity towards particular peers; the answer there is usually traffic engineering rather than queue management, although I've seen WRED turned on as a short-term measure to make the helpdesk phone ring less while more OC12s are turned up. One last wave of the hands: just because the backbone is clear and free, and rarely needing to queue a packet, doesn't mean that one edge or another of a flow (or both) isn't competing with other traffic as part of a multi-access wireless network, oversubscribed back-haul from a DSLAM or a CATV network at 4pm in the winter when the neighbourhood kids come back from school. Joe Attachment:
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