[Chilli] Chilli Digest, Vol 63, Issue 14

Alexandru Gheorghe alghe.global at gmail.com
Sat Mar 7 10:27:57 UTC 2015 

If there's offloading on the nic, shouldn't this be seen at kernel level
from L2 and up? Why when raised by CPU (the offloaded packets) to be routed
to the router/appliance itself for the application the bandwidth drops?

It is rather curious it happens to an HTTP proxy application too. But so
far your investigation regarding the 100mb/s points to this with coova
disabled. If I may, I'd like to question if your setup involves any bridges.

Normally the only things that come into my mind are:
1) starting with kernel 2.37 iirc the bridge is set down if there's no
uplink with beat detected on it/down;

2) the way chilli captures traffic packets is to create a tun interface in
order to access the kernel side of routing packets (an usual hook like
netfilter does, similarly).

The first I think does not apply to your case and I can't seem to find any
explanation how it can affect you. The second could be one of the reasons
in a chain of symptoms that gives you the result.

Anyways, I'm rather curious right now to know if indeed offloading on the
NIC was the cause. Any results?

Alex

--
; Alexandru Gheorghe
; alghe.global {at} gmail {com}

; sent from mobile
On Feb 28, 2015 2:54 AM, "David Bird" <dbird at google.com> wrote:

> You can use --tcpmss to clamp the TCP MSS. But, I agree, your issue is
> very likely gso related. Something like "sudo ethtool -K eth1 gro off"
>
> On Fri, Feb 27, 2015 at 2:00 PM, Richard REY <richard at rexy.fr> wrote:
>
>> Yes, but this doesn't explain why there isn't any problem when the flows
>> pass through the appliance. this issue is seen only when the TCP flows is
>> sent to an internal processes
>>
>> I'll try to disable packet off-loading next monday.
>> I'll also try to forbid the "jumbo frame" on NIC
>>
>> Rexy
>>
>> Le 27/02/2015 20:50, Alexandru Gheorghe a écrit :
>>
>>  Usually fragmentation needed means you need to adjust the MTU of your
>>> nic.
>>>
>>> Alex
>>>
>>>
>>> On 02/26/2015 02:30 PM, Claus Stjernoe wrote:
>>>
>>>> Hi Richard,
>>>>
>>>> Try to disable packet off-loading on the Gigabit NIC.
>>>>
>>>> Kind regards,
>>>> Claus
>>>>
>>>> -----Oprindelig meddelelse-----
>>>> Fra: chilli-bounces at coova.org [mailto:chilli-bounces at coova.org] På
>>>> vegne af chilli-request at coova.org
>>>> Sendt: 26. februar 2015 13:00
>>>> Til: chilli at coova.org
>>>> Emne: Chilli Digest, Vol 63, Issue 14
>>>>
>>>> Send Chilli mailing list submissions to
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>>>>
>>>>
>>>> Today's Topics:
>>>>
>>>>     1. Re: Chilli Digest, Vol 63, Issue 12 (Richard REY)
>>>>
>>>>
>>>> ----------------------------------------------------------------------
>>>>
>>>> Message: 1
>>>> Date: Wed, 25 Feb 2015 22:48:56 +0100
>>>> From: Richard REY <richard at rexy.fr>
>>>> To: chilli at coova.org
>>>> Subject: Re: [Chilli] Chilli Digest, Vol 63, Issue 12
>>>> Message-ID: <54EE4348.2090503 at rexy.fr>
>>>> Content-Type: text/plain; charset=windows-1252; format=flowed
>>>>
>>>> Hi,
>>>> I use COOVA in its last version (SVN revision 492) running on an
>>>> ALCASAR appliance (mageia 4.1 - kernel 3.14.32), all is OK excepted a flow
>>>> issue.
>>>> When a TCP stream goes across the appliance there isn't any flow issue
>>>> (forward mode). BUT when a TCP stream is sent inside the appliance (to a
>>>> HTTP proxy for example) the observed flow is very weak (Input mode). The
>>>> problem is maximal when the card connected to COOVA is in the Gigabit mode.
>>>>
>>>> Our investigation :
>>>>   From the appliance, we try to download a file located on a FTP server
>>>> connected on the network controlled by COOVA. Without COOVA the observed
>>>> flow in gigabit mode is about 888Mb/s whereas with COOVA we can see just
>>>> 68 Kb/s (YES 68 Kb/s). Regarding the packets exchanged we can see ICMP
>>>> packets sent by the appliance (Destination unreachable (Fragmentation
>>>> needed).
>>>> We found a by-pass ?solution? by fixing the speed of the card to
>>>> 100Mb/s. At this speed the phenomenon is practically invisible (just one
>>>> ICMP packet sent) and the flow approaches the maximum supported by the
>>>> network card. On a virtual machine where we can't fix Ethernet speed, we
>>>> must choose a 100Mb/s virtual Ethernet card when building the VM.
>>>> We have the Pcap file of our investigation. I say it again, this issue
>>>> is seen only when the TCP flows is sent to an internal processes (in
>>>> 'forward' mode all is ok).
>>>>
>>>> Regards
>>>> Rexy & ALCASAR team
>>>>
>>>> Le 23/02/2015 08:59, kl a ?crit :
>>>>
>>>>> I see problem on kernel version > 3.7 right up to 3.10.  Above 3.10
>>>>> not tested.
>>>>> However, in the other quoted post, it says kernel 2.6.39 upto 3.3.4.
>>>>> Above that not tested.
>>>>> Something not consist here.
>>>>>
>>>>> So which kernel version you guys are using which are seeing this
>>>>> problem ?
>>>>>
>>>>>
>>>>> On Monday, February 23, 2015 3:13 PM, Danny Magat <danny at sb-ps.ae>
>>>>> wrote:
>>>>> This problem is still exist on my setup.
>>>>> http://lists.coova.org/pipermail/chilli/2013-November/002437.html
>>>>>
>>>>> I hope that somebody will give us a hint on how to solve this.
>>>>>
>>>>> Regards,
>>>>> Danny
>>>>>
>>>>> -----Original Message-----
>>>>> From: chilli-bounces at coova.org [mailto:chilli-bounces at coova.org] On
>>>>> Behalf Of chilli-request at coova.org
>>>>> Sent: Sunday, February 22, 2015 4:00 PM
>>>>> To: chilli at coova.org
>>>>> Subject: Chilli Digest, Vol 63, Issue 12
>>>>>
>>>>> Send Chilli mailing list submissions to
>>>>>       chilli at coova.org
>>>>>
>>>>> To subscribe or unsubscribe via the World Wide Web, visit
>>>>>       http://lists.coova.org/cgi-bin/mailman/listinfo/chilli
>>>>> or, via email, send a message with subject or body 'help' to
>>>>>       chilli-request at coova.org
>>>>>
>>>>> You can reach the person managing the list at
>>>>>       chilli-owner at coova.org
>>>>>
>>>>> When replying, please edit your Subject line so it is more specific
>>>>> than
>>>>> "Re: Contents of Chilli digest..."
>>>>>
>>>>>
>>>>> Today's Topics:
>>>>>
>>>>>      1. Too sharp upload bandwidth limit on 1gbps wired network (kl)
>>>>>
>>>>>
>>>>> ----------------------------------------------------------------------
>>>>>
>>>>> Message: 1
>>>>> Date: Sun, 22 Feb 2015 02:21:53 +0000 (UTC)
>>>>> From: kl <kl522 at yahoo.com>
>>>>> To: Chilli List <chilli at coova.org>
>>>>> Subject: [Chilli] Too sharp upload bandwidth limit on 1gbps wired
>>>>>       network
>>>>> Message-ID:
>>>>>       <122480453.6349415.1424571713923.JavaMail.yahoo at mail.yahoo.com>
>>>>> Content-Type: text/plain; charset=UTF-8
>>>>>
>>>>>
>>>>>
>>>>> Nobody is facing this issue with coova chilli ?
>>>>>
>>>>> http://www.coova.org/node/5171
>>>>>
>>>>> https://github.com/coova/coova-chilli/issues/32
>>>>>
>>>>> Happens only on Gigabit wired network and certain kernel verson.
>>>>> Applies to 1.2.9, 1.3.0 and other versions ....
>>>>>
>>>>>
>>>>> ------------------------------
>>>>>
>>>>> _______________________________________________
>>>>> Chilli mailing list
>>>>> Chilli at coova.org
>>>>> http://lists.coova.org/cgi-bin/mailman/listinfo/chilli
>>>>>
>>>>>
>>>>> End of Chilli Digest, Vol 63, Issue 12
>>>>> **************************************
>>>>>
>>>>>
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>>>>>
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>>>> End of Chilli Digest, Vol 63, Issue 14
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