[VoiceOps] NENA SIP Marking Specifications

[Hiers, David]

Hi Brian,

That standard applies to " Emergency Services IP Networks", which, by definition, are entirely private.   They control their entire universe; there is simply no reason for NENA to care about default behavior of any device or network.

As to why they picked these values...  I have no idea, but they defined 'most networks' as out of scope, so why not?

David


-----Original Message-----
From: VoiceOps [mailto:voiceops-bounces at voiceops.org] On Behalf Of Brian Knight
Sent: Tuesday, March 17, 2020 2:22 PM
To: Voiceops <voiceops at voiceops.org>
Subject: [VoiceOps] NENA SIP Marking Specifications

I have been working to deploy a new private WAN for a customer that services E911 emergency calls delivered over VoIP.  While working on this, I learned that their DSCP markings for SIP control traffic are AF12, not AF31 or CS3 which is what I typically see from our other enterprise customers.  Media is still marked EF.

These markings appear to have been standardized by a body called NENA, National Emergency Number Association.  Googling 'NENA SIP "AF12"' 
returns the relevant PDFs.  Below is a sample from their standards guide.

DSCP | Use                              | PHB
-----+----------------------------------+--------
0    | Routine Traffic                  | Default
1    | 9-1-1 Signaling                  | AF12
2    | 9-1-1 Text Media                 | AF12
3    | 9-1-1 Audio Media                | EF
4    | 9-1-1 Video Media                | AF11
5    | 9-1-1 Non-human-initiated Call   | AF21
6    | Intra ESInet* Events             | AF21
7    | Intra ESInet Other 9-1-1 Traffic | AF22

(* Emergency Services IP Network)

Does anyone know the reasoning behind specifying SIP as AF12 instead of AF31?  While developing these standards, was NENA aware that AF12 tends to be prioritized lower than AF31 on most networks?

Just trying to get some background on the decision.

Thanks,

-Brian
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