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Re: Is anyone actually USING IP QoS?
- From: Alex P. Rudnev
- Date: Wed Jun 16 06:25:11 1999
First of all, may be there is some other place for this, _more
theoretical_, discussion? On the other hand, I do not want to lost this
Then, what I and Vadim are speaking about, it is not _efficiency_. No one
bother on _efficiency_ in the real life, all (at least network admins)
are bothered about _enougph/not_enougph_ issue. It's a difference.
For now, there is the source of multimedia - different HTTP sites over
the world; there is a beatiful protocols like realvideo or streamvideo,
used by the thousands. And there is bottlechecks - not the LAN's but
inter-domain links, not the ethernet's but inter-sea cables.
Then, I'd like to make one issue clean enougph. If your LAN is not the
bottlecheck, the difference between multicasting and packet replication
became nonimportant (except may be the server power). On the other hand,
the packet replication is the caching with the zero expiration time. And
(on the third hand -:)) the 90% of existing multimedia context is
ON-DEMAND context, not the live context.
This resumes into the conclusion - it's much more efficient to start from
L4 replication or reflection, may be _ON THE FLY, HIDDEN_ reflection.
This technique can be implemented on the single ISP and allow him to
improve access to the ALL over-world multimedia sources, just at once.
Then, if sometimes LAN became bottlecheck, just the same replication
server can be used to translate unicast to multicast. Anyway, our (ISP)
experience show us _not to allow the customers to ask multicasting at the
L2/L3 level_, and don't use multicasting over the domain/AS boundaries -
let's it be for the _future generation_ internet.
And then, if we replace _on-the-fly_ replication to the _short expiration
time caching_, we'll cover _multimedia on demand_ requests as well.
Note - this do not need extra routing schemas, extra routing protocols
(except, may be, some fixed reservations done for the cache itself), no
extra inter-domain negotiations, etc etc. And it can be easily converted
to the local multicasting in the future.
And L4 replication/caching means _you have the same name space as http,
you have a flexible control protocols like SIP, etc etc - you can control
this service as well_. Not as in L2/L3 case (someone ask 188.8.131.52/255
multicast, should I allow it or not - nobody know; who should pay for
this - nobody know, how to stop this - nobody know...).
Just as it was saying, _even elephant can fly_. But starting multimedia
services from the multicasting is _to send elephant to fly_. May be, in
future, we'll need an elephant to fly; for now, we need something like
the _flying bat_ - but we need it just in time, not since 20 years.
We have 'played' with MBONE, we have 'played' with WebTV. But we just
'work' with RV and such services, just this days. May be, we'll stop to
play with the _flying elephants_ and start from the _flying bat's_ first?
> But we're not discussing that. we're discussing multicast v/s unicast (or was
> it QoS?), but you're somehow tying the two together when they're completely
> different things.
Yes, we changes the subject during this discussion. -:)
But this is _an answer_ - no one use QoS because it meant _multicasting_
mainly, and multicasting can't be deployed over the global internet this
days. But no one need QoS inside their internal network (usially, there
is exceptions); and we can't provide inter-domain QoS yet.
> and are you suggesting that dense-mode (blindly distributing), to coin the
> term, is more efficient than say, sparse-mode (multicast?) .. not even in your
> bare logics world.
Just again. It'e enougph in our world to use the dense-mode, except some
special cases, If it should be not enougph, we'll say it -:).
> relies on the underlying layers which b) are not oblivious to such DoS attacks
> .. in todays Internet (maybe not yours, but todays) where 2 million line
> prefix filters are about as real as millions of multicast groups.
And show me this millions of multicast groups -:). There is 10 - 20 such
groups over the whole russia. Try to get one or two - and you'll get an
angry message from the network admin. Etc. It's _play_ for now, not the
real work yet.
I'd like to stopp this thread here too; but I think this _replication_
and _short-time-caching_ must be concerned in the new session-initiation
protocols. It's easy to start from this end.
Aleksei Roudnev, Network Operations Center, Relcom, Moscow
(+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager)
(+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)