Subject: Re: Flow Label

From: Scott Bradner <[email-masked]>
Date: Thu, 27 Dec 2001 09:09:58 -0500 (EST)

Brian sez:
> Disagree. The QOS usages are clear and well-defined. The others are all
> pretty dumb.

I disagree on both parts of this 

Brian thinks the "other" uses for the flow label are dumb, I happen to agree
but the people who made the proposals did not think they were dumb - I
do not claim to have perfect knowledge of all things

Brian also says that the QOS usages are clear and well-defined, I see
no reason to think this is the case

The issues of how to use Diffserv and what interdomain QOS mean are 
complex and not captured by the 24 bits the WG has in play 

Who can say that it is even useful to know half way around the world
what a sender wanted for QoS when there is no way to know if that sender 
had authority or local priority to ask for that QoS and, at least at this
time, there is no way for the remote ISP to do settlements to get
paid for treating the packet in any way other than best effort

I think that a lot of work needs to be done on what QoS means in 
an inter-domain world before we can even guess if e2e QoS has any meaning.

I think Tony's proposed text is nice but it is only a cellophane fig
leaf over the fact that we have no idea how to "do" QoS in the real-world
Internet. I see no particular advantage to adopting the text.

Scott

(ps - for a data point in the mutability camp, Cisco IP phones are designed 
with two Ethernet jacks, one to connect to the wall jack - the desktop 
machine is to be plugged into the other.  The phone clears the DSCP on 
all packets it forwards from the desktop and sets the DSCP to 5 on all 
of its own data packets - I assume to protect the infrastructure from 
applications on the desktop that might overwhelm the net with packets 
marked as high priority)

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From: Brian E Carpenter <[email-masked]>
Date: Thu, 27 Dec 2001 15:49:08 +0100

> do not claim to have perfect knowledge of all things

Neither do I. I do have reasons for the statement I made, but since there
have been no proposals that I've seen for the other uses (except that
the CATNIP-like label swapping idea morphed into MPLS) it doesn't
seem worth analysing vague ideas.

> no reason to think this is the case

I think this has been covered adequately in other messages for Intserv
and Diffserv, with specific detail.

> complex and not captured by the 24 bits the WG has in play

Nobody said they are. The issue is getting something minimal and
unambiguous into the IPv6 spec before it's too late. 

> paid for treating the packet in any way other than best effort

These issues will never be resolved unless we have the bare bones
of a mechanism to build on. 

> an inter-domain world before we can even guess if e2e QoS has any meaning.

Indeed, for the general case. But there are scenarios involving relatively
small sets of sites and ISPs where we can see how to construct e2eQOS.

> Internet. I see no particular advantage to adopting the text.

I think it is better than MBZ text simply because it sets some boundary
conditions that we can work with. MBZ text just stops all work on this
topic for the foreseeable future.

> applications on the desktop that might overwhelm the net with packets

Right, and this is a hangover from the days before the EF code point was
assigned, and we were advising experimenters to use Precedence 5 for EF
tests. 

   Brian

---

From: "Jim Fleming" <[email-masked]>
Date: Thu, 27 Dec 2001 11:47:17 -0600

----- Original Message ----- 
From: "Brian E Carpenter" <[email-masked]>
To: "Scott Bradner" <[email-masked]>
> assigned, and we were advising experimenters to use Precedence 5 for EF

If the phone has RIFRAF Routing, then you can ping it and have it
go into IPv4++ mode.

Also, 5 is for Audio - Telephone Quality
0x55 for Phone to Phone

The special 0x0* or 0x*0 codes are for Conference Room exchanges
0000 5 - 0101 Audio - Telephone Quality
   Individual Microphone
0000 6 - 0110 Audio - CD Quality Stereo
   Room Speakerphone
5 - 0101 0000 Audio - Telephone Quality
   Center Speaker
 6 - 0110 0000 Audio - CD Quality Stereo
   Surround Speakers
----

See also Dr. Dobb's Journal - Cover Story on vPC
February 1984 - Issue #88 - Page 32.

Jim Fleming
http://www.IPv8.info
IPv16....One Better !!