Did Internet Founders Actually Anticipate Paid, Prioritized Traffic?
nonobvious at gmail.com
Sun Sep 19 01:59:37 CDT 2010
On Sat, Sep 18, 2010 at 2:34 AM, JC Dill <jcdill.lists at 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.
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