[Cake] diffserv based on firewall mark

Wed Oct 12 08:40:04 EDT 2016

There is no need for cleansing dscp for wan ingress, I think it is
unnecessary, too

In https://www.bufferbloat.net/projects/codel/wiki/Cake/

There is a statement:

"The only way we know how to “fix” bittorrent is to classify it somewhat,
somehow, as “background”."

But in fact, there is no simply way to classify bittorrent INGRESS traffic

DSCP -> unreliable, easily spoofed by attacker, and the value is most
likely 0x0
firewall mark -> cake do not use firewall mark/connmark

Finally, I guess most likely home users will use bit torrent.

2016年10月12日 下午8:04，"moeller0" <moeller0 at gmx.de>寫道：

> Hi Ching?
>
> > On Oct 12, 2016, at 12:17 , ching lu <lsching17 at gmail.com> wrote:
> >
> >
> > 2016年10月12日 下午6:05，"moeller0" <moeller0 at gmx.de>寫道：
> > >
> > > Hi Ching,
> > >
> > > > On Oct 12, 2016, at 11:35 , ching lu <lsching17 at gmail.com> wrote:
> > > >
> > > > How to archive "cake follows iptables"? is it “wan ingress ->
> iptables
> > >
> > > Yes.
> > >
> > > > -> wifi egress/LAN egress -> ifb egress -> cake”?
> > >
> > >         Except that if you instantiate cake on the interface
> connecting to the outers LAN/WLAN side (lets call this LAN for short), cake
> will reside on that interfaces egress and hence you require no ifb for
> traffic coming in from the internet (as a plus cake will even without the
> fancy new deNAT options see the full intrnal IP addresses, useful for dual
> and triple isolation options). In the direction facing the internet you can
> instantiate cake on an ifb interface for LAN and then put the iptables DSCP
> cleaner on the WAN egress side (and the WAN ingress side, unless you trust
> your ISP to deliver reasonable DSCP values, which should be like never*)
> >
> > The bandwidth shaper won’t work correctly if cake(s) are registered on
> multiple LAN interface, ifb is necessary
> >
> > e.g. if ingress bandwidth limit is 100M, then setting 50M on wifi, and
> 50M on LAN ?
>
>         Yes that seems true, if you instantiate cake on br-lan (which I
> believe would be the relevant interface) you will shape both wireless and
> wired traffic, but most likely also internal traffic… But that can be
> solved by one more router/AP ;)
>
> >
> > I think the diffserv support of cake model is not suitable for home
> network currently.
>
>         I have no real opinion on that, but could you explicitly state
> what short coming you see that is a showstopper? DSCP cleaning on ingress
> is BTW not really required to happen before cake, as long as cake is set to
> besteffort it will ignore DSCP markings anyway, and if you want to
> re-map/re-classify packets vie DSCP on ingress you are pretty much out of
> scope for a typical home network. Cleaning up on egress, as to not leak
> internal configuration to the upstream seems indeed sub-optimal, but cake
> is not alone in that regard…
>
> > The setup is much more complex
>
>         Well, DSCP setup is complex no matter how you slice and dice it…
> but maybe you have an idea what a shaper (like cake) could/should do to
> make this simpler?
>
> Best Regards
>         Sebastian
>
> >
> >
> >
> > >
> > > Best Regards
> > >         Sebastian
> > >
> > > 8) DSCP are only ever guranteed to be meaninful inside a dscp domain,
> and in reality your home net is a different domain from the ISP’s. It would
> have been nice if the DSCP field would have been separeted into 2 3bit
> fields, the first for the actual sender to request one of 8 differential
> classes and the other 3bits for the current domain to store its actually
> used DSCP bits. I claim the 3 bits should be enough for anybody  ;)
> > >
> > >
> > > >
> > > >
> > > > On Wed, Oct 12, 2016 at 5:10 PM, moeller0 <moeller0 at gmx.de> wrote:
> > > >> Hi,
> > > >>
> > > >>
> > > >>> On Oct 12, 2016, at 10:11 , ching lu <lsching17 at gmail.com> wrote:
> > > >>>
> > > >>> For egress, setting DSCP field should work.
> > > >>>
> > > >>> iptables -> wan egress -> cake
> > > >>>
> > > >>> But is it possible to set DSCP to 0x0 after cake's classification?
> i
> > > >>> do not know how ISP handle non-zero DSCP, there seems to be no
> > > >>> standard for this.
> > > >>
> > > >>        Interestingly cake, at some point in the past offered
> exactly that functionality, but it got removed due to added complexity with
> very little practical applicability (and a potential layering violation,
> but one could equally argue that the current layering is partly
> sub-optimal/wrong and hence violating it to better reflect reality might be
> acceptable). But current cake does not offer this. If you are willing to
> daisy-chain two routers, you could run cake on the respective egress
> interfaces connecting both routers, and do the DSCP cleaning on the outer
> router’s egress interface toward the internet…
> > > >>
> > > >>>
> > > >>>
> > > >>> For ingress, DSCP field may not be set by network peer at all, and
> i
> > > >>> have multiple LAN interfaces
> > > >>>
> > > >>> AFAIK, the order is "wan ingress -> ifb egress -> cake -> iptables"
> > > >>>
> > > >>> The trick of setting DSCP by iptables do not work because cake
> comes first
> > > >>
> > > >>        Hence Jonathan’s recommendation to make sure that cake
> follows iptables, by setting it up on egress interfaces only…
> > > >>
> > > >> Best Regards
> > > >>        Sebastian
> > > >>
> > > >>>
> > > >>> On Wed, Oct 12, 2016 at 3:26 PM, Jonathan Morton <
> chromatix99 at gmail.com> wrote:
> > > >>>>
> > > >>>>> On 12 Oct, 2016, at 08:52, ching lu <lsching17 at gmail.com> wrote:
> > > >>>>>
> > > >>>>> I deprioritize bittorrent traffic by marking related connections
> in
> > > >>>>> iptables (e.g. detect by port number) and route them to
> corresponding
> > > >>>>> HTB class and qdisc.
> > > >>>>>
> > > >>>>> How can i archive the same goal using the cake qdisc?
> > > >>>>
> > > >>>> Modify your iptables rules to set the DSCP rather than a
> kernel-internal mark.  You probably want "-j DSCP —set-dscp-class CS1”, as
> CS1 is the “bulk low priority” code.  Cake’s default Diffserv mode will
> pick that up appropriately.
> > > >>>>
> > > >>>> You also need to make sure Cake sees your packets *after* they’ve
> been through the firewall, which generally means attaching it to the egress
> port in each direction, not the ingress port.  You’ve probably already done
> this, if you’re happy with your HTB setup.
> > > >>>>
> > > >>>> If you have multiple LAN interfaces (eg, both Ethernet and wifi),
> you should loop the inbound traffic through a common IFB device (and attach
> Cake to that instead of the physical interfaces) to simplify configuration.
> > > >>>>
> > > >>>> - Jonathan Morton
> > > >>>>
> > > >>> _______________________________________________
> > > >>> Cake mailing list
> > > >>> Cake at lists.bufferbloat.net
> > > >>> https://lists.bufferbloat.net/listinfo/cake
> > > >>
> > >
> >
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.bufferbloat.net/pipermail/cake/attachments/20161012/fbc2e879/attachment-0001.html>