Hello David,
Thank you for your answer. Indeed, I have (in this case) an agreement with the
ISP to I can play with QoS fields.
=> I don't understand why in the documentation they refer to old ToS field and
not DSCP field that everyone use. That would be more logic.
I did captures and found ToS 0x10 or 0x8 (transfert)
IP (tos 0x10, ttl 64, id 6849, offset 0, flags [DF], proto TCP (6), length 52)
According to what I read tos 0x10 = DSCP 2 and tos 0x8 = DSCP 2 ?
ToS 0x10 in binary 1010 = dscp 10 => 2 and ToS binary 8 in binary 1000 = dscp
10 => 2
Low delay should be 0x1000 and throughput should be 0x100
https://tools.ietf.org/html/rfc1349
4. Specification of the TOS Field
I tried with openbsd 6.3
Also why these values were chosen by default in Openbsd, according to QoS
models I would have chosen other values and also used dscp instead of ToS
Regards
Le mercredi 8 août 2018 à 11:31:39 UTC+2, Dahlberg, David
<david.dahlb...@fkie.fraunhofer.de> a écrit :
Am Dienstag, den 07.08.2018, 19:29 +0000 schrieb Mik J:
> Does anyone knows what means lowdelay and thoughput for IPQoS
> parameter ?
Bits 3 and 4 of old IP TOS field.
> To what DSCP correspond these words
You have to calculate it yourself. The lowest bit of the 6-bit DSCP is
"private". The second and third lowest once have been T and D.
I did indeed write a script which translates me a given value from one
interpretation into the gazillion other possible interpretations. Maybe
I push it to Githup soonish.
"T" is e.g. AFx1 and AFx3 equivalents.
"L" is e.g. AFx2 and AFx3.
> I did a capture when writing ls in my terminal and I see DSCP=cs0.
> I would have expected something else.
CSx in DSCP directly equates to IP precedence in old TOS interpretation
with all the special bits (DTRC0) set to zero. CS0 = DF (default
forwarding) is all zero.
But honestly, what do you want to set those values for? They have only
local meaning -> So you can do something with them in your local
network. If you're sending them across a administrative border, they
lose meaning (unless something special has been negotiated between you
and your ISP) and it is quite possible they are set to zero anyways.
With regular internet access, all you can do is set the DSCP to a "well-
known" value and hope that there is somebody out there who (a) does
process it, (b) interprets the same way as you and (c) he did receive
your value unchanged (which is not guaranteed).
An example for such well-known values which "may" have "some" effect
"somewhere" is mostly EF for VoIP.
Cheers
David
