Question regarding QoS Configuration for SIP Trunks (and understanding of SIP Trunks)
I am hoping someone can provide some clarification and recommended QoS treatment for SIP Trunks.
In my environment I have several remote sites that leverage SIP trunks over the WAN between remote PBX/gateways and a centrally hosted Voice Mail system. We are now having conversations about how to properly classify and mark the SIP trunk traffic.
Where my confusion lies, is SIP is a signaling protocol, and further to that point Cisco’s recommendation from a QoS perspective is to mark it as cs3, with other signaling traffic.
Why this confuses me, how does the voice bearing traffic (to/from the vmail server) get transported.
- Does the call to the vmail via the SIP trunk, initiate another flow for the voice bearing traffic (i.e. rtp flow),
- Are those packets voice bearing packets somehow encapsulated within SIP ?
If the latter, then is it common to place SIP traffic in a LLQ ?
Any feedback/insight would be greatly appreciated.