Is anyone actually USING IP QoS?
Alex P. Rudnev
alex at Relcom.EU.net
Tue Jun 15 17:51:55 UTC 1999
> >_is_ caching, with zero retention time) - w/o associated security and
> >scalability problems. Presenting L2/L3 multicasting as the best or the
> >or even a meaningful way to reduce transmission duplication is quite
> research or data to support these assertions?
> and how does caching magically negate security and scalability concerns?
> what tools are you using to do content replication/management that scale to
> thousands of hosts/caches? even if i assume caching is as efficient, or
> more so, than multicast, i'm still just trading one set of
> security/scalability concerns for others. caching is no more a silver
> bullet than multicast.
In case of simple replication _on the fly_ or translation _unicast to
multicast_, this is the same from point of view of effieiency.
But multicst suppose to do perlication at the L2 level, where you have no
information about the context, about _time to expire_ (how multicast
helps you to decrease traffic in case of AUDIO-ON-DEMAND_ if I ask some
nw song, and you ask the same song 10 seconds later - but remember, such
requests are no popular then _Live audio_ requests except some events).
If case of _caching on the fly_ you have all L4 (not L3 but L4)
information, it's flexible level and vendor can easily add _time to
expire_ into his live stream.
Just again, multicasting is the END of L4 caсhing, not the beginning. And
when I analyse existing network, I saw the useless of multicasting
_except_ some special cases (such as some live streams in case of
And I think the idea _to start from multicsting_ was wrong from th first
moment of time. You should END by multicasting - when you ahev a network
of media sources, a network of media customers, the set of policies
installed over the world - you can use multicasting locally to improve
the local throughput. But try to build multicast network this days - the
thouthand of hackers will be happy -:), and a lot of ISP refuse to
PS. I never saw the multimedia really need multicasting on the L2 level
-:). But I see a lot of multimedia where L4 caching can improve quality
dramatically. Every day.
> >I think blaming vendors for inability to build products which run faster
> >than the proven lower boundaries for the required kind of algorithms is,
> >er, strange.
> i won't deny the potential scalability problems but i think your
> generalizing/oversimplifying to say caching just works and has no security
> or scalability concerns.
It's amazing, but please name ANY securyty concern appeared due to WWW
caching -:). It's not ideal solution (you can't cache SSL sessions, for
example, through you can cache signed or crypted sessions - image PRP
crypted multimedia session, for example), but I can't remember any
security problem with it.
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)
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