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From: Roland Bless <roland.bless@kit.edu>
To: Mikael Abrahamsson <swmike@swm.pp.se>
Cc: Victor Hou <victor.hou@broadcom.com>, bloat@lists.bufferbloat.net
Subject: Re: [Bloat] [Ecn-sane] [iccrg] Fwd: [tcpPrague] Implementation and experimentation of TCP Prague/L4S hackaton at IETF104
Date: Sat, 23 Mar 2019 20:45:27 +0100	[thread overview]
Message-ID: <9eca8199-1276-f225-0e6c-a64b99035159@kit.edu> (raw)
In-Reply-To: <alpine.DEB.2.20.1903231813040.3161@uplift.swm.pp.se>

Hi Mikael,

On 23.03.19 at 18:16 Mikael Abrahamsson wrote:
> On Sat, 23 Mar 2019, Roland Bless wrote:
> 
>> It's true that DSCPs may be remarked, but RFC 2474
>> already stated
>>
>>   Packets received with an unrecognized codepoint SHOULD be forwarded
>>   as if they were marked for the Default behavior (see Sec. 4), and
>>   their codepoints should not be changed.
> 
> https://mailman.nanog.org/pipermail/nanog/2015-May/075004.html
> 
> https://www.nanog.org/mailinglist/mailarchives/old_archive/2005-05/msg00654.html

This is pretty sad. The correct answer to the first question
"does Internet trust IP DSCP marking?" should have been twofold:
a) don't trust already present markings on ingress
  for your own supported PHBs (except default and LE PHBs :-)
  unless you have agreed with the neighboring
  DS domain.
b) Packets received with an unrecognized DSCP SHOULD be forwarded
   as best effort and their DSCP should NOT be changed.

The BCP to unconditionally bleach (set to 0) is IMHO simply wrong: one
has to distinguish between treating as default PHB and overwriting the
DSCP. For internally supported DSCPs/PHBs one typically needs to bleach
(but e.g., not for LE), but for all unsupported DSCPs simply map them to
the default PHB.
It's true that Diffserv's major line of defense is the domain
boundary that needs to protect the domain's resources against
unauthorized use. So a domain that internally supports EF should not
honor incoming EF marked packets from untrusted/unadmitted sources, and
therefore must bleach them. For unsupported DSCPs though,
one could simply _map_ them to the default PHB while retaining the DSCP.

> Please note the dates, as in 4 and 14 years ago respectively.
> 
> So please read those threads and then tell me that what you quoted above
> has bearing on reality.

It's clear that just setting everything to DSCP 0 is the safe option
(in case one has no full control over all equipment etc.),
but it has the mentioned drawback of limiting the future extensibility.
Since Diffserv requires a configurable mapping of DSCP to PHB
a consistent configuration should be possible, nevertheless.

Regards
 Roland

  reply	other threads:[~2019-03-23 19:45 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-22 18:28 Victor Hou
2019-03-23  8:02 ` Roland Bless
2019-03-23  8:54   ` Luca Muscariello
2019-03-23 10:02   ` Mikael Abrahamsson
2019-03-23 15:03     ` Jonathan Morton
2019-03-23 19:52       ` Roland Bless
2019-03-23 15:19     ` Roland Bless
2019-03-23 17:16       ` Mikael Abrahamsson
2019-03-23 19:45         ` Roland Bless [this message]
2019-03-23 17:48       ` Michael Welzl
2019-03-23 18:31         ` Luca Muscariello
2019-03-23 18:40           ` Mikael Abrahamsson
2019-03-23 19:11             ` Michael Welzl
2019-03-23 21:04             ` Luca Muscariello
2019-03-23 19:55         ` Roland Bless
     [not found] <AM0PR07MB48198660539171737E4CCAB1E0730@AM0PR07MB4819.eurprd07.prod.outlook.c om>
     [not found] ` <d91a6a71-5898-9571-2a02-0d9d83839615@bobbriscoe.net>
2019-03-15 10:46   ` [Bloat] " Dave Taht
2019-03-15 13:01     ` Sebastian Moeller
2019-03-15 14:06       ` Dave Taht
2019-03-15 15:52         ` Sebastian Moeller
2019-03-15 17:01           ` [Bloat] [Ecn-sane] " David P. Reed
2019-03-15 17:45             ` Sebastian Moeller
2019-03-15 18:36             ` Mikael Abrahamsson
2019-03-15 19:23               ` Sebastian Moeller
2019-03-15 19:32               ` Jonathan Morton
2019-03-15 19:44                 ` David P. Reed
2019-03-15 20:13                   ` Jonathan Morton
2019-03-15 23:43                     ` David P. Reed
2019-03-16  1:26                       ` Jonathan Morton
2019-03-16  7:38                       ` Sebastian Moeller
2019-03-16 18:56                         ` Michael Richardson
2019-03-15 20:28                 ` Jonathan Foulkes
2019-03-15 20:31                   ` Dave Taht
2019-03-15 23:45                     ` David P. Reed
2019-03-16  9:42                       ` Michael Welzl
2019-03-16 10:08                         ` Sebastian Moeller
2019-03-16 10:23                           ` Nils Andreas Svee
2019-03-16 14:55                             ` Jonathan Foulkes
2019-03-16 21:38               ` Holland, Jake
2019-03-16 21:57                 ` Vint Cerf
2019-03-16 22:03                   ` Dave Taht
2019-03-16 22:05                   ` Holland, Jake
2019-03-17 18:07                   ` David P. Reed
2019-03-17 18:05                     ` Vint Cerf
2019-03-19  1:06                     ` Bob Briscoe
2019-03-19  3:18                       ` Dave Taht
2019-03-20 19:04                       ` Holland, Jake
2019-03-20 19:58                         ` Stephen Hemminger
2019-03-20 20:05                           ` Holland, Jake
2019-03-20 21:48                         ` Greg White
2019-03-20 21:56                           ` Jonathan Morton
2019-03-20 22:38                           ` Holland, Jake
2019-03-20 22:56                             ` Greg White
2019-03-20 23:29                         ` Bob Briscoe
2019-03-20 23:51                           ` Jonathan Morton
2019-03-21  6:04                             ` Bob Briscoe
2019-03-21  7:46                               ` Jonathan Morton
2019-03-21  8:02                                 ` Bob Briscoe
2019-03-21  8:49                                   ` Bless, Roland (TM)
2019-03-21 13:24                                     ` Bob Briscoe
2019-03-22 12:53                                       ` Bless, Roland (TM)
2019-03-25  2:47                                         ` Bob Briscoe
2019-03-21  8:45                               ` Sebastian Moeller
2019-03-24 20:15                           ` alex.burr
2019-03-25  1:34                             ` Bob Briscoe
2019-03-27 17:52                               ` Alex Burr
2019-03-19  4:44                     ` Greg White
2019-03-19  5:35                       ` Jonathan Morton
2019-03-19  5:52                         ` Greg White
2019-03-19  7:10                           ` Jonathan Morton
2019-03-19  8:07                             ` Sebastian Moeller
2019-03-19  8:50                       ` Sebastian Moeller
2019-03-19 23:59                       ` Dave Taht
2019-03-20 10:17                         ` Sebastian Moeller
2019-03-16 22:03                 ` Jonathan Morton
2019-03-16 22:09                 ` Sebastian Moeller
2019-03-17 14:06                 ` Mikael Abrahamsson
2019-03-17 17:37                   ` Loganaden Velvindron
2019-03-17 17:40                     ` Toke Høiland-Jørgensen
2019-03-17 17:44                     ` Mikael Abrahamsson
2019-03-17 18:00                       ` Dave Taht
2019-03-17 19:38                     ` Rodney W. Grimes
2019-03-17 20:50                   ` Luca Muscariello
2019-03-17 21:51                     ` Toke Høiland-Jørgensen
2019-03-18  4:26                     ` Mikael Abrahamsson
2019-03-16  4:04             ` Jonathan Morton
2019-03-16  4:51               ` Dave Taht
2019-03-15 18:07         ` Mikael Abrahamsson

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