I do agree with your point regarding the possibility of differentiated
services QoS degrading router performance. In my opinion it may add slight
delays in transport. However, I do see a benefit in offering more than two
service levels. I guess that you can say that assured forwarding and
expedited forwarding can be combined and implemented as the "real-time"
service level. This is another topic of discussion though.
Tina Iliff
-----Original Message-----
From: jag(_at_)kw(_dot_)com(_dot_)cn [mailto:jag(_at_)kw(_dot_)com(_dot_)cn]
Sent: Wednesday, February 07, 2001 7:44 PM
To: ietf(_at_)ietf(_dot_)org
Subject: RE: An alternative to TCP (part 2)
I have a question:
If the traffic class field in the IPv6 header was changed, as suggested,
to
a set of flags, then how would a full gammit of differentiated services be
indicated? In other words, if there is only one flag indicating type of
service, then different levels of, for example, assured forwarding or
expedited forwarding cannot be supported or implemented.
I think for the sake of routing system performance it's better to provide
only two classes of services: real-time (expediated forwarding) and
best-effort (classical IP service level). I think it's better not to
implement assured forwarding in routing system, or the network layer but
instead in the end-node system, or the transport protocol layer.
Other quality of service parameter such as peak bit rate, sustained bit
rate, guarranteed frame rate may be associated with the IPv6 flow label.