[Cake] flow isolation with ipip

[Pete Heist]

I don’t know if this helps, but I think this should work. :) I used IPIP tunnels (with and without FOU encapsulation) over a point-to-point WiFi bridge as a way of testing Cake over WiFi without traffic being prioritized by the Linux WiFi stack or WMM, for example. The WiFi stack “sees" the outer IPIP packet, and treats it with whatever diffserv marking is on the outer packet, rather than what’s on the inner packet that’s encapsulated. I applied Cake to the tunnel device, which seemed to see the packets before encapsulation, and it worked well. I think it should also work for flow isolation.

I can go through my setup scripts and get more specific if need be, to make sure I’m not leading anyone astray. I think the important part is that Cake be applied to the tunnel device and not just a regular device that’s carrying IPIP traffic...

> Message: 1
> Date: Thu, 17 Aug 2017 02:55:17 +0300
> From: Jonathan Morton <chromatix99 at gmail.com>
> To: Cong Xu <davidxu06 at gmail.com>
> Cc: Cake List <cake at lists.bufferbloat.net>
> Subject: Re: [Cake] flow isolation with ipip
> Message-ID:
> 	<CAJq5cE0qSNrbzUufzaup3sZyeKaN=R=JAfqREojbyK6pFAyzDw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
> 
> Cake makes use of Linux' "packet dissecting" infrastructure.  If the latter
> knows about the tunnelling protocol, Cake should naturally see the IP and
> port numbers of the inner payload rather than the outer tunnel.
> 
> I don't know, however, precisely what tunnels are supported. At minimum,
> don't ever expect encrypted tunnels to behave this way!
> 
> - Jonathan Morton
> 
> On 18 Jun 2017 21:13, "Cong Xu" <davidxu06 at gmail.com> wrote:
> 
>> Hi,
>> 
>> I wonder if cake's flow isolation works with the ipip tunnel? I hope to
>> guarantee the networking fair-share among containers/VMs in the same host.
>> Thus, I used sfq/fq to associate with each tc class created in advance to
>> provide both shaping and scheduling. The scripts roughly look like this
>> (Assume 2 containers hosting iperf client run in the same host. One
>> container sends 100 parallel streams via -P 100 to iperf server running in
>> another host, the other one send 10 parallel streams with -P 10.):
>> 
>> tc qdisc add dev $NIC root handle 1: htb default 2
>> tc class add dev $NIC parent 1: classid 1:1 htb rate ${NIC_RATE}mbit
>> burst 1m cburst 1m
>> tc class add dev $NIC parent 1:1 classid 1:2 htb rate ${RATE1}mbit ceil
>> ${NIC_RATE}mbit burst 1m cburst 1m
>> tc class add dev $NIC parent 1:1 classid 1:3 htb rate ${RATE2}mbit ceil
>> ${NIC_RATE}mbit burst1m cburst 1m
>> tc qdisc add dev $NIC parent 1:2 handle 2 sfq perturb 10
>> tc qdisc add dev $NIC parent 1:3 handle 3 sfq perturb 10
>> tc filter ad ...
>> 
>> It works well, each container running iperf gets the almost same bandwidth
>> regardless of the flows number. (Without the sfq, the container sending 100
>> streams acchieves much higher bandwidth than the 10 streams guy.)
>> 
>> -------------- simultaneous 2 unlimited (100 conns vs 10 conns)
>> -------------
>> job "big-unlimited-client" created
>> job "small-unlimited-client" created
>> -------------- unlimited server <-- unlimited client (100 conns)
>> -------------
>> [SUM]   0.00-50.01  sec  24.9 GBytes  4.22 Gbits/sec  16874
>> sender
>> [SUM]   0.00-50.01  sec  24.8 GBytes  4.21 Gbits/sec
>> receiver
>> 
>> -------------- unlimited server <-- unlimited client (10 conns)
>> -------------
>> [SUM]   0.00-50.00  sec  24.4 GBytes  4.19 Gbits/sec  13802
>> sender
>> [SUM]   0.00-50.00  sec  24.4 GBytes  4.19 Gbits/sec
>> receiver
>> 
>> However, if the ipip is enabled, sfq dose not work anymore.
>> 
>> -------------- simultaneous 2 unlimited (100 conns vs 10 conns)
>> -------------
>> job "big-unlimited-client" created
>> job "small-unlimited-client" created
>> -------------- unlimited server <-- unlimited client (100 conns)
>> -------------
>> [SUM]   0.00-50.00  sec  27.2 GBytes  4.67 Gbits/sec  391278
>> sender
>> [SUM]   0.00-50.00  sec  27.1 GBytes  4.65 Gbits/sec
>> receiver
>> 
>> -------------- unlimited server <-- unlimited client (10 conns)
>> -------------
>> [SUM]   0.00-50.00  sec  6.85 GBytes  1.18 Gbits/sec  64153
>> sender
>> [SUM]   0.00-50.00  sec  6.82 GBytes  1.17 Gbits/sec
>> receiver
>> 
>> The reason behind is that the src/dst ip addresses using ipip tunnel are
>> same for all flows which are the src/dst ip of the host NICs instead of
>> veth ip of each container/VM, and there is no ports number for the outside
>> header of ipip packet. I verified this by capturing the traffic on NIC and
>> analyzing it with wireshark. The real src/dst ip of container/VM is visible
>> on the tunnel device (e.g. tunl0). Theoretically, this issue can be solved
>> if I set up tc class and sfq on tunl0 instead of host NIC. I tried it,
>> unfortunately, it did not work either. fq does not work for the same
>> reason, because both sfq and fq use the same flow classifier (src/dst ips
>> and ports). So, I just wonder if cake works with ipip tunnel or not.
>> 
>> I appreciate if you can provide any help based on your expertise. Thanks.
>> 
>> Regards,
>> Cong
>> 
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