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Aastra 57i phone, Netgear GS748TS GS724TS switches and Trixbox 2.6.2.2

a_lemin
Posts: 231
 Member Since:
2007-01-21
Submitted by a_lemin on Wed, 08/26/2009 - 1:41am.

Hello all,
I am trying to setup QoS properly for our small telephony system.
We have around 10 Aastra 57i phones and a Trixbox 2.6.2.2 server connected to Netgear GS724TS switch.

What are the default QoS settings on the 57i?
Does it set CoS or DSCP flags on the packets, and if so which ones so I can match the flags on Trixbox and the switches?

I know what do do with the VLANs etc, but I need to know what packets to prioritize.
The Chapter 5 of the manual (ftp://downloads.netgear.com/files/GS700TS_UM_12Jun09.pdf) covers how to configure QoS. However I am not sure whether to setup CoS or DSCP and then which flags etc to prioritize to match the default QoS values in /etc/asterisk/sip_general_additional.conf;
tos_sip=cs3
tos_audio=ef
tos_video=af41

Thank you in advance.
Andy.

‹ Aastr 53i "Double NAT" MWI ›

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a_lemin
Posts: 231
 Member Since:
2007-01-21
Figured it out
Thu, 08/27/2009 - 6:02am

Trixbox 2.6.2.2
Default values;
/etc/asterisk/sip_general_additional.conf
tos_sip=cs3 (011000 = 24) ; Sets TOS for SIP packets.
tos_audio=ef (101110 = 46) ; Sets TOS for RTP audio packets.
tos_video=af41 (100010 = 34) ; Sets TOS for RTP video packets.
NB; We are not interested in Video.

Aastra 57i Phones
Default Values;
SIP (tos_sip) = 26
RTP (tos_audio) = 46
RTCP (tos_audio) = 46

Netgear Switch Stack
Therefore need to step increase priorities for packets with flags ‘011000’=24, ‘011010’=26 and ‘101110’=46.
Switches need configuring to use DSCP QoS with strict priority;
DSCP.cs3 (Packet Flags: 011000 = 24) changed from ‘Low’ to ‘Normal’ priority queue.
DSCP.af31 (Packet Flags: 011010 = 26) changed from ‘Low’ to ‘Normal’ priority queue.
DSCP.ef (Packet Flags: 101110 = 46) changed from ‘Normal’ to ‘High’ priority queue.


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mcconnellt
Posts: 58
 Member Since:
2008-05-25
Why did you feel the need to
Thu, 08/27/2009 - 8:11am

Why did you feel the need to change the mapping?

Quote:
DSCP to Queue Mapping
• DSCP In – Displays the incoming packet’s DSCP value. The following DSCP In values are predefined: 3, 11, 19, 27, 35, 43, 51, 59.
• Queue – Select the traffic-forwarding queue to which the DSCP is mapped. Four traffic priority queues are supported (Lowest, Low, Normal and High). The High Queue is reserved for special traffic and is not recommended for use.

ef should be normal and 24/26 should be low with everthing else on lowest. Also note that you will have to let iptables set the DSCP value as Asterisk cannot do it.

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