From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Daniel Golle <daniel@makrotopia.org>,
Florent Daigniere <nextgens@freenetproject.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
WireGuard mailing list <wireguard@lists.zx2c4.com>
Subject: Re: passing-through TOS/DSCP marking
Date: Thu, 17 Jun 2021 14:24:29 +0200 [thread overview]
Message-ID: <87sg1gptky.fsf@toke.dk> (raw)
In-Reply-To: <YMsYrpAm/29Q91GX@makrotopia.org>
Daniel Golle <daniel@makrotopia.org> writes:
> Hi Florent,
>
> On Thu, Jun 17, 2021 at 07:55:09AM +0000, Florent Daigniere wrote:
>> On Thu, 2021-06-17 at 01:33 +0200, Toke Høiland-Jørgensen wrote:
>> > Daniel Golle <daniel@makrotopia.org> writes:
>> >
>> > > Hi Jason,
>> > >
>> > > On Wed, Jun 16, 2021 at 06:28:12PM +0200, Jason A. Donenfeld wrote:
>> > > > WireGuard does not copy the inner DSCP mark to the outside, aside
>> > > > from
>> > > > the ECN bits, in order to avoid a data leak.
>> > >
>> > > That's a very valid argument.
>> > >
>> > > However, from my experience now, Wireguard is not suitable for
>> > > VoIP/RTP
>> > > data (minimize-delay) being sent through the same tunnel as TCP bulk
>> > > (maximize-throughput) traffic in bandwidth constraint and/or high-
>> > > latency
>> > > environments, as that ruins the VoIP calls to the degree of not
>> > > being
>> > > understandable. ECN helps quite a bit when it comes to avoid packet
>> > > drops
>> > > for TCP traffic, but that's not enough to avoid high jitter and
>> > > drops for
>> > > RTP/UDP traffic at the same time.
>> > >
>> > > I thought about ways to improve that and wonder what you would
>> > > suggest.
>> > > My ideas are:
>> > > * have different tunnels depending on inner DSCP bits and mark them
>> > > accordingly on the outside.
>> > > => we already got multiple tunnels and that would double the
>> > > number.
>> > >
>> > > * mark outer packets with DSCP bits based on their size.
>> > > VoIP RTP/UDP packets are typically "medium sized" while TCP
>> > > packets
>> > > typically max out the MTU.
>> > > => we would not leak information, but that assumption may not
>> > > always
>> > > be true
>> > >
>> > > * patch wireguard kernel code to allow preserving inner DSCP bits.
>> > > => even only having 2 differentl classes of traffic (critical vs.
>> > > bulk) would already help a lot...
>> > >
>> > >
>> > > What do you think? Any other ideas?
>> >
>> > Can you share a few more details about the network setup? I.e., where
>> > is
>> > the bottleneck link that requires this special treatment?
>>
>> I can tell you about mine. WiFi in a congested environment: "voip on
>> mobile phones". WMM/802.11e uses the diffserv markings; most commercial
>> APs will do the right thing provided packets are marked appropriately.
>>
>> At the time I have sent patches (back in 2019) for both the golang and
>> linux implementation that turned it on by default. I believe that
>> Russell Strong further improved upon them by adding a knob (20190318 on
>> this mailing list).
>
> Thank you very much for the hint!
> This patch is exactly what I was looking for:
> https://lists.zx2c4.com/pipermail/wireguard/2019-March/004026.html
>
> Unfortunately it has not received a great amount of feedback back then.
> I'll try forward-porting and deploying it now, because to me it looks
> like the best solution money can buy :)
I think you can achieve something similar using BPF filters, by relying
on wireguard passing through the skb->hash value when encrypting.
Simply attach a TC-BPF filter to the wireguard netdev, pull out the DSCP
value and store it in a map keyed on skb->hash. Then, run a second BPF
filter on the physical interface that shares that same map, lookup the
DSCP value based on the skb->hash value, and rewrite the outer IP
header.
The read-side filter will need to use bpf_get_hash_recalc() to make sure
the hash is calculated before the packet gets handed to wireguard, and
it'll be subject to hash collisions, but I think it should generally
work fairly well (for anything that's flow-based of course). And it can
be done without patching wireguard itself :)
-Toke
next prev parent reply other threads:[~2021-06-17 12:24 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 13:24 passing-through TOS/DSCP marking Daniel Golle
2021-06-16 16:28 ` Jason A. Donenfeld
2021-06-16 19:26 ` Daniel Golle
2021-06-16 23:33 ` Toke Høiland-Jørgensen
2021-06-17 7:55 ` Florent Daigniere
2021-06-17 9:41 ` Daniel Golle
2021-06-17 12:24 ` Toke Høiland-Jørgensen [this message]
[not found] ` <CAMaqUZ09KRtp01OK3u-Di52X_kH9eT4E-wmnPc6QzjSCd5dEiw@mail.gmail.com>
2021-06-17 20:54 ` Toke Høiland-Jørgensen
2021-06-17 23:04 ` Toke Høiland-Jørgensen
2021-06-18 12:24 ` Jason A. Donenfeld
2021-06-21 12:36 ` Daniel Golle
2021-06-21 14:27 ` Toke Høiland-Jørgensen
2021-06-30 17:23 ` Daniel Golle
2021-06-30 20:55 ` Toke Høiland-Jørgensen
2021-07-04 14:15 ` Daniel Golle
2021-07-05 15:21 ` Toke Høiland-Jørgensen
2021-07-05 16:05 ` Daniel Golle
2021-07-05 16:59 ` Toke Høiland-Jørgensen
2021-07-05 17:26 ` Daniel Golle
2021-07-05 21:20 ` Toke Høiland-Jørgensen
2021-07-06 7:00 ` Florent Daigniere
2021-07-06 20:08 ` Luiz Angelo Daros de Luca
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87sg1gptky.fsf@toke.dk \
--to=toke@toke.dk \
--cc=Jason@zx2c4.com \
--cc=daniel@makrotopia.org \
--cc=nextgens@freenetproject.org \
--cc=wireguard@lists.zx2c4.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).