[e2e] QBONE abandon QoS research ?
simon at limmat.switch.ch
Mon Nov 8 12:05:50 PST 2004
Olivier Bonaventure writes:
> Research networks like I2 or GEANT in Europe are often
> overprovisionned and do not necessarily need QoS.
As someone who helps run such a network (a small European "NREN"),
I tend to agree.
> Furthermore, their customers usually do not pay directly
True in some places. Our users (R&E institutions) certainly do pay us
directly. Our charging scheme is probably at least as complex as any
commercial ISP's, and includes volume- (differentiated by destination
and time of day) and access-rate-based components.
Because we do charge our users, we have LESS, not more need for QoS
mechanisms in our network, because we can maintain a healthy (if slow)
feedback loop between user behavior and the resources available for
upgrading the backbone. (Although most "end" users don't pay or even
see our bills, they get various kinds of signals from those who do.)
Given our cost structure and the approximate elasticities of customer
traffic demand and willingness to pay, I'm pretty sure that we can
continue building out our backbone in this overprovisioned regime for
many years to come. On the other hand we're not here to make money,
although we do compete with commercial ISPs in a way.
> and there is no strict incentive for stringent SLAs.
As some of us serve hospitals and such, the question of well-defined
SLAs does come up occasionally even for research networks. It's true
that customers tend to feel more entitled to SLAs when they pay for
the service directly. It's also true that the uptake of SLAs in the
research network space is slow, but I don't think lack of QoS
mechanisms is an important reason for that.
How "tight" or "stringent" these SLAs need to be is another question.
In many cases customers are mostly interested in availability
guarantees. Others say they need N Mb/s guaranteed bandwidth, but in
fact they are only worried that they can transfer M Megabytes of bulk
data through our network and back every afternoon and be damn sure
that the results are back in time for the evening news whether
> Commercial ISPs have stringent QoS needs. See :
[pointers to two papers by employees of a large vendor of expensive
QoS-capable core network equipment explaining network operators why
they need this]
(Why does this make me think of Randy Bush talking about "IntServ,
DiffServ, and SelfServ"? :-)
I know many commercial ISPs that don't have stringent QoS needs.
Or maybe they just don't know it yet.
Of course those that do probably make all the money. Whether they add
sufficient value to justify the additional complexity in the long run
is another question.
Note that I do think a mechanism like diffserv is a great tool to have
in my toolkit. I just hope I'll never have to use it :-)
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