Hi Dan

When you say that you defeated the Traffic Shaping altogether, did you set it 
to 0K or something else?

Regards
Michael Knill




On 03/03/2013, at 7:59 AM, Dan Ryson <[email protected]> wrote:

> Hello Lonnie,
> 
> Thanks for the advice.   I'll give your 0 K bits-per-second "Downlink" 
> setting a try.  I suspect that'll work for us based on the following 
> observation, made shortly after I send my most recent e-mail.
> 
> While downloading a bunch of files at a high bandwidth and listening to 
> drop-outs on incoming voice traffic, we tried a wide range of "Downlink" 
> speeds, from 500 K all the way up to 30,000 K.  (Our advertised rate is 
> 27/7.)  Because the severity of drop-outs lessened but persisted at the 
> higher rate settings, we tried defeating Traffic Shaping all together.  
> As soon as we did, the dropouts were eliminated.  (Kind of ironic...)
> 
> Dan
> 
> 
> 
> On 03/01/2013 04:48 PM, Lonnie Abelbeck wrote:
>> Hi Dan,
>> 
>> I would suggest you try setting the "Downlink Speed:" to "0" K 
>> bits-per-second, and give that a try.
>> 
>> This special case will disable all downlink 'shaping', which for the 
>> downlink is simply dropping packets coming in faster than the rate specified.
>> 
>> The only real true 'shaping' can be done on the Uplink where packets are 
>> prioritized before being sent.  Even with the "Uplink Speed" at the 
>> advertised rate, there is about 25% headroom for VoIP traffic built-in.  For 
>> example, with a 4 Mbps UP connection and "Uplink Speed:" set to "4000" K 
>> bits-per-second, HTTP (low priority) traffic UP will be limited to about 3 
>> Mbps and about 1 Mbps headroom is reserved for VoIP.
>> 
>> My guess is your such low Downlink Speed and the new "more accurate" 
>> downlink shaping, it is dropping downlink VoIP packets when that threshold 
>> is met.
>> 
>> Previous to AstLinux 1.1.0 the method used to shape the downlink did not 
>> work properly for all ethernet NIC's, the current method works for all NIC's 
>> we have access to test.
>> 
>> In general, some may disagree with me, but 'shaping' Downlink traffic by 
>> dropping packets in a VoIP environment seems like a bad idea.  Of course 
>> there may be special cases when shaping Downlink traffic is fine, 
>> particularly if it is primarily TCP traffic and not VoIP.
>> 
>> Personally on my Cable Modem - AstLinux setup, my "Downlink Speed:" is set 
>> to "0" K bits-per-second and my "Uplink Speed:" is set to my typical real 
>> speed when traffic shaping is disabled.  I use "htb" as well.
>> 
>> Lonnie
>> 
>> 
>> 
>> 
>> On Feb 28, 2013, at 11:39 AM, Dan Ryson wrote:
>> 
>>> All,
>>> 
>>> I'm reviving this old thread to inquire whether recent changes in 1.1.0
>>> traffic shaping (outlined below) might affect how best to adjust specific
>>> QOS settings.
>>> 
>>> ChangeLog 1.1.0_1 includes this little nugget:
>>> 
>>>  AIF traffic-shaping, incoming (ingress) traffic shaping now uses "avrate"
>>> for more accurate shaping.
>>>  Note: This new approach is somewhat more aggressive than previously,
>>> increasing the limit may be desired.
>>> 
>>> I'm asking because we're experiencing a new symptom whenever someone in the
>>> office downloads large files at high speeds.  We experience periodic (every
>>> 1.5 seconds or so) audio dropouts on incoming voices only.  This is a new
>>> symptom for us that we would be delighted to fix.
>>> 
>>> We're using "htb" with what we believe to be very conservative settings:
>>> 
>>> * UP/DOWN speeds are set at 30% of "advertised" ISP values.  (We've tried
>>> less radical settings too.)
>>> * VoIP UDP Ports are defined to match those specified in RTP.conf
>>> * DSCP markings are set in sip.conf as Lonnie recommended below
>>> 
>>> Any thoughts?
>>> 
>>> Thanks,
>>> 
>>> Dan
>>> 
>>> -----Original Message-----
>>> From: Lonnie Abelbeck [mailto:[email protected]]
>>> Sent: Saturday, November 17, 2012 11:58 PM
>>> To: AstLinux Users Mailing List
>>> Subject: Re: [Astlinux-users] QoS and Traffic Shaping
>>> 
>>> Michael,
>>> 
>>> Because of historical reasons, the Firewall tab -> VoIP UDP Ports: field
>>> needs to have a value, so use the RTP range so it has a value and makes sure
>>> that UDP range has priority.  But yes, the DSCP values would be used
>>> otherwise.
>>> 
>>> Personally I would not re-write DSCP values via the switch unless you have
>>> problems that can't be solved any other way.  Note that SHAPER_P2P_HOSTS can
>>> contain CIDR values as well as single IP addresses to control bandwidth
>>> hogs, though some would look upon that as too generalized and heavy handed
>>> as well.
>>> 
>>>> So am I correct in saying that EF will go in High Priority and CS3 in
>>> medium priority.
>>> 
>>> Yes.
>>> 
>>>> It says SIP Signalling is default for Medium Priority. Is that
>>> classification via Port 5060:5064 on UDP (and TCP/TLS) or via CS3 DSCP
>>> classification (or both)?
>>> 
>>> Not sure what you are asking.  In the traffic shaper plugin, the
>>> classify_by_host (SHAPER_P2P_HOSTS) and classify_by_port (SHAPER_xxx_PORTS)
>>> are applied first, and finally classify_by_dscp_class for any remaining
>>> unclassified.
>>> 
>>> I know people that use the IP Phone's DATA ports for PC's, so the voice is
>>> placed on a VLAN and the DATA is untagged, using different subnets existing
>>> on the same wire, here you can use the switch's 802.1p VLAN priority's to
>>> prioritize traffic before it even hits the edge where the AstLinux traffic
>>> shaper resides.  In this case PC file server access and such can effect
>>> voice quality over the local drop without some help from the switch.
>>> 
>>> Keep in mind traffic shaping is as much of an art as it is a science.
>>> 
>>> Lonnie
>>> 
>>> 
>>> On Nov 17, 2012, at 8:55 PM, Michael Knill wrote:
>>> 
>>>> Thanks Lonnie. Oops I didn't look at the config file.
>>>> 
>>>> So from what you are saying, I don't even need to set these ports if I am
>>> setting DSCP correctly. In fact would it be better if I actually left them
>>> blank?
>>>> I intend on creating QoS Trust boundaries which I can do on the switch.
>>> This will rewrite all DSCP to 0 for untrusted hosts (PC's) and the DSCP is
>>> trusted for IP Phones.
>>>> Of course Soft Phones break this concept.
>>>> 
>>>> So am I correct in saying that EF will go in High Priority and CS3 in
>>> medium priority. It says SIP Signalling is default for Medium Priority. Is
>>> that classification via Port 5060:5064 on UDP (and TCP/TLS) or via CS3 DSCP
>>> classification (or both)?
>>>> Thanks very much for your help as always.
>>>> 
>>>> Regards
>>>> Michael Knill
>>>> 
>>>> 
>>>> 
>>>> 
>>>> On 18/11/2012, at 1:06 PM, Lonnie Abelbeck wrote:
>>>> 
>>>>> Michael,
>>>>> 
>>>>> Personally I use "htb", seems to give me the best results.  I think the
>>> newer 'hfsc' might work well for general mixed traffic, but I have found
>>> that 'hfsc' is too slow to adjust for VoIP to be its best.
>>>>> Personally I set my Down/Up speed right at my advertised values (28 M / 4
>>> M), if you want to knock them down by 5% that would be fine, a good starting
>>> point.  This will automatically leave about 20% of the up-link free for the
>>> highest priority class.  If you need more than 20% for your SIP traffic,
>>> then you can reduce you up-link speed value.
>>>>> Regardless you should test by calling yourself via an
>>> inside-to-outside-to-inside call, place yourself on hold, listen to the hold
>>> music.  Then run a speed-test, the up-link test will show the worst case
>>> scenario.
>>>>> #1 ) In this day and age much of the traffic will be classified by DSCP
>>> markings by default, which is honored, but be sure to set those in sip.conf:
>>>>> --
>>>>> tos_sip=cs3                     ; Sets TOS for SIP packets.
>>>>> tos_audio=ef                    ; Sets TOS for RTP audio packets.
>>>>> tos_video=af41                  ; Sets TOS for RTP video packets.
>>>>> tos_text=af41                   ; Sets TOS for RTP text packets.
>>>>> --
>>>>> https://wiki.asterisk.org/wiki/display/AST/IP+Quality+of+Service
>>>>> 
>>>>> Setting the SIP RTP port range is still fine, and what we had to do in
>>> the Asterisk 1.2 days.
>>>>> You can also do some tweaks here:
>>>>> 
>>>>>> From the Network tab -> Firewall Plugins: [ traffic-shaper ]
>>>>> You can define/tweak some of the priorities, but the defaults should be
>>> good for the typical situation.  Should you have a NAS doing offsite backups
>>> or such, you may want to define SHAPER_P2P_HOSTS.
>>>>> 
>>>>> #2)  A 5% reduction is fine, you could start with no reduction and start
>>> from there.  Each ISP probably has it's own sweet spot. Be sure to test.
>>>>> 
>>>>> #3)  Downlink shaping is not as critical since the bottleneck is usually
>>> on the up-link, but it simply discards bursts of data higher than the limit.
>>>>> It seems to me that getting quality voice connections is easier today
>>>>> than it was a few years ago.  Possibly the bigger pipes are the
>>>>> reason, possibly some traffic shaping is done by the ISP ?  I don't
>>>>> use IAX anymore. :-)  Also people are now so used to cell phones,
>>>>> crappy audio is tolerated more than it was in the past. :-)
>>>>> 
>>>>> Regardless enabling traffic shaping is good practice, if for nothing else
>>> to control buffer-bloat.
>>>>> Bufferbloat
>>>>> http://en.wikipedia.org/wiki/Bufferbloat
>>>>> 
>>>>> Lonnie
>>>>> 
>>>>> PS: We use 'tc' in the traffic shaper plugin to perform the shaping.
>>>>> 
>>>>> 
>>>>> On Nov 17, 2012, at 3:53 PM, Michael Knill wrote:
>>>>> 
>>>>>> To the group
>>>>>> 
>>>>>> I realise that I don't completely understand how the traffic shaping
>>> works on AstLinux and I really need to.
>>>>>> I have set the following:
>>>>>> 
>>>>>> Type - I am using hfsc which I assume is the best Downlink speed - I
>>>>>> am setting this to slightly less than than my DSL modems reported
>>>>>> speed e.g. 95% Uplink speed -  I am setting this to slightly less
>>>>>> than than my DSL modems reported speed e.g. 95% VoIP UDP Ports -
>>>>>> 16384:16639. The same as I have set in rtp.conf
>>>>>> 
>>>>>> My questions are:
>>>>>> 
>>>>>> 1) Does the script only use the VoIP ports for queue classification. It
>>> appears that even though I have the range set in rtp.conf, it only affects
>>> my allocated port and not the destination port to my Service provider which
>>> is not in this range? Wont this mean that I am not prioritising rtp on my
>>> uplink? Can I force symmetrical RTP port allocation?
>>>>>> 2) Is 95% ok for the reduction. Does anyone use a different formula
>>>>>> 3) How does the Downlink traffic shaping work? Does it just restrict the
>>> traffic flow of non VoIP traffic (e.g. not in the VoIP UDP Port Range) to
>>> fit the Downlink traffic shaping envelope?
>>>>>> What is everyone else doing?
>>>>>> 
>>>>>> Regards
>>>>>> Michael Knill
>>> 
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