On Sat, Sep 18, 2010 at 2:34 AM, JC Dill <jcdill.lists@gmail.com> wrote:
Jack Bates wrote:
And yet, I'm pretty sure there are providers that have different pipes for business than they do for consumer, and probably riding some of the same physical medium. This creates saturated and unsaturated pipes, which is just as bad or worse than using QOS. The reason I'm pretty sure about it, is business circuits generally are guaranteed, while consumer are not.
I'm pretty sure you are mistaken. The reason is, it's adding an additional layer of complexity inside the network for no good reason.
Real ISPs have all sorts of different layers of complexity, for lots of reasons ranging from equipment performance to Layer 8 differences to mergers&acquisitions to willingness-to-pay to marketing objectives to historical accident. An ISP that's also a telco-ish carrier will typically offer multiple services at Layer 1, Layer 2, MPLS, Layer 3, and other variants on transport. Copper's different economically from fiber pairs, SONET, Ethernet, CWDM, DWDM, some services get multiplexed by using bundles of copper or fiber, some get multiplexed by using different kinds of wavelength or time division, some get shared by packet-switching, some packet switches are smarter on some transport media than on others, some services will use edge equipment from Brand C or J or A because they were the first or cheapest to get Feature X when it was needed, some services are designed for Layer 9 problems like different taxes on different kinds of access services. An ISP that isn't an end-to-end vertically integrated provider will be buying stuff from other carriers that influences what services they offer, but the integrated providers often do that too. There are some kinds of service where the difference between business-grade and consumer-grade is mainly about options for types of billing, or for guarantees around how fast they'll get a truck to your place to fix things - that's especially common in access networks. Most consumer home internet service is running on DSL or cable modems, and that's going to behave differently than T1 access or 10 Gbps WAN-PHY or LAN-PHY gear. Different priced services may get connected to circuits or boxes that have different amounts of oversubscription. Different protocols give you different feedback mechanisms that affect performance. Or higher-priced services may have measuring mechanisms built in to them or bolted alongside, so that performance problems can generate a trouble ticket faster or get a refund on the bill, and come with a sales person who doesn't really understand how they work but is being pressured to provide 110% uptime. A common design these days is to have an MPLS backbone supporting multiple services including private networks and public internet, and the private networks may get dedicated chunks of the trunking, or may get higher MPLS prioritization. But separately from that, the IP edges may support Diffserv, and maybe the backbones do or maybe they don't, or maybe some parts of the trunking are only accessible to the higher-priority services. And maybe the diffserv gets implemented differently on the equipment that's used for different transmission media, or maybe the box that has the better port density doesn't have as many queues as the lower-density box, or maybe it's different between different port cards with the same vendor. A very common design is that businesses can get diffserv (or the MPLS equivalents) on end-to-end services provided by ISP X, but the peering arrangements with ISP Y don't pass diffserv bits, or pass it but ignore it, or use different sets of bits. It's very frustrating to me as a consumer, because what I'd really like would be for the main bottleneck point (my downstream connection at home) to either respect the diffserv bits set by the senders, or else to give UDP higher priority and TCP lower priority, and put Bittorrent and its ilk in a scavenger class, so VOIP and real-time video work regardless of my web activity and the web gets more priority than BitTorrent. -- ---- Thanks; Bill Note that this isn't my regular email account - It's still experimental so far. And Google probably logs and indexes everything you send it.