with which TOS value does Asterisk 1.4 mark packets (voip.ms equipment)

[lifespeed]

I would like to act on the TOS field inbound from voip.ms. I currently have QOS setup in my Draytek Vigor 2130, and can see the outgoing packets are prioritized. Incoming packets are not prioritized, although this router has the ability to do so. I asked voip.ms support and got the following response:

Hi, we don't set a TOS in our packet, calls are delivered by asterisk clusters. We can't tell your router how to prioritize our packets, this has to be done on your side.

Our Asterisk clusters are currently in the 1.4 branch, and we use the default asterisk TOS setting, I hope this help.

I know I set DSCP values in my phones on my PIAF purple (* 1.8.3.2) PBX. I'm not sure if Asterisk would set these values in the absence of a value set by the phone, like when packets are inbound from the PSTN through voip.ms Asterisk 1.4 servers.

I would like to try and apply QOS based on incoming DSCP/TOS values. What is the 'default' value configured in * 1.4?

 

[dswartz]

I thought he said they don't mark the packets? What are you trying to solve?

 

[lifespeed]

Sounds to me like he is not completely sure what they do:

"Our Asterisk clusters are currently in the 1.4 branch, and we use the default asterisk TOS setting"

They use * 1.4, so my question is, what does asterisk do in it's default configuration? I think *1.8 will use the existing DSCP value set by the endpoint, if it exists. I may be wrong about this, but I think it can also set the DSCP value if none is present. But that is *1.8.

I am trying to get my router to prioritize inbound VoIP packets, something that is easily accomplished if I know which TOS/DSCP value to set as high priority.

 

[lifespeed]

Hi Dan,

Perhaps you answered my question a couple years ago on the FreePBX forum?

"SIP is cs3 and RTP is ef."

Wouldn't be the first question you've helped with, thanks. I'll try this out tonight.

Edit: for completeness
tos_sip=cs3 ; Sets TOS for SIP packets. DSCP 0x18 dec 24
tos_audio=ef ; Sets TOS for RTP audio packets. DSCP 0x24 dec 46
tos_video=af41 ; Sets TOS for RTP video packets. DSCP 0x22 dec 34

 

[dswartz]

Ah, yeah, I remember that post now Keep in mind that it is possible that backbone routers along the way may very well discard any TOS/DSCP info.