[e2e] Re: crippled Internet
schulzrinne at cs.columbia.edu
Wed Apr 25 05:52:01 PDT 2001
The problem is that average utilization is not a good indication of
usable quality of service. If the access circuit is overloaded (drops a
significant amount of packets) 1% of the time, this is probably not
enough to warrant doubling your connection expense, but it is enough to
violate typical service requirements for multimedia and VoIP
In addition, we have the problem (probably common to universities) that
we get spikes of outbound traffic when a machine has been hacked and
converted into a firehose. That can cause significant overload on even
our OC-3. Sure, the sys admin will filter the traffic within a few
minutes, but again, this ruins any on-going high-QOS applications.
Access QOS is far easier to implement than end-to-end QOS, since issues
of administrative coordination are more readily dealt with. Doesn't
solve all the problems (particularly inbound traffic), but most of our
traffic is outbound, courtesy of the file sharing generosity of our
student body. We effectively deal with this by restricting the access
bandwidth from the dorms to the rest of the university, but that's a
fairly crude approach.
Here, the main problem would be to ensure that any resource reservation
or other filtering is reasonably secure against compromise.
RJ Atkinson wrote:
> At 20:41 24/04/01, Fred Baker wrote:
> >None of them talk about the link between them and their customer, which they view as out of their control - out of sight and out of mind. They also offer the customer few QoS options and often very little information about what is going on at the SP end of that link.
> >Hence, customer figures he bought a link from an ISP and it should work, and ISP thinks the customer provided it, so nobody is taking responsibility for it. Three guesses where I think the real problem tends to be.
> All of the big ISPs that I'm familiar with let customers
> see the bandwidth utilisation graph for the interface from
> the ISP POP router pointing at the customer POP router. Many
> of them have internal alarms set when that utilisation crosses
> some threshold -- to trigger having a sales person contact the
> customer about whether they want a larger uplink circuit.
> Maybe I'm not following your thoughts above, but I think
> that the ISPs are doing their bit to keep customers reasonably
> informed about their tail circuit -- though the motive is profit.
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