Using the Flow Label with Dual-Stack Lite Chris Donley (CableLabs) & Kirk Erichsen (Time Warner Cable)

QoS for Dual-Stack Lite DS-Lite encapsulates IPv4 inside IPv6 Obfuscates IPv4 5-tuple Difficult for intermediate devices to classify traffic inside DS-Lite tunnel based on IPv4 5-tuple In a COPS (RFC 2748) framework, Policy Decision Point (PDP) sees different traffic than Policy Enforcement Point (PEP) PDP sees IPv4 traffic; PEP sees IPv6 (DS-Lite) Problematic for Service Providers to offer mission critical applications that require prioritized per-flow service (e.g. voice) through the DS-Lite tunnel

Use Case: PacketCable MultiMedia(PCMM) PCMM uses a COPS (RFC 2748) framework for QoS Application Manager (AM)/Policy Server (PS) identify flows AM/PS tells CMTS to apply DOCSIS QoS Classifiers DOCSIS QoS Classifiers based on IPv4/IPv6 headers + transport port/ protocol Problem: IPv4 traffic classified by AM/PS does not match IPv6 traffic classified by CM/CMTS

Solution Classify traffic based on IPv6 Flow Label at ingress to DS-Lite tunnel B4 and AFTR calculate Flow Label per IPv4 5-tuple Apply Flow Label to DS-Lite IPv6 header Every packet in the flow uses the same Flow Label PDP calculates flow label value By querying AFTR, or Through IPv4 5-tuple hash PDP instructs Policy Enforcement Point (e.g. CMTS) to use Flow Label as QoS classifier

Why Not Use DiffServ? Service Providers don’t trust home user DSCP values If the B4 is behind the CM (non-embedded), the CM needs to perform Deep Packet Inspection QoS reservations based on Flow Label are dynamic Handled by AM/PS based on IPv4 5-tuple Model does not require trust boundary extended to users DSCP does not allow differentiation of voice streams All voice traffic would be marked the same (DSCP 46) If the QoS reservation were sized for one call, a second call would impair voice quality for both 20-bit flow label allows per-call differentiation QoS based on Flow Label is consistent with PCMM COPS model and its objectives Per flow QoS for specific applications such as voice

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An Example… CM and CPE Devices CMTS (PEP) RKS Managed Backbone DOCSIS DSx CMTS (PEP) RKS RADIUS Managed Backbone IQoS Policy Server (PDP) COPS IMS Core (VoIP) Policy Server (PDP) COPS IMS Core (VoIP) IMS Core submits policy request to Policy Server (PDP) 2 CMTS (PEP) manages service flow and generates event messages 4 RKS RADIUS Voice session proceeds with reliable, predictable access network QoS 5 Policy Server (PDP) authorizes request and creates a service flow on CMTS (PEP) 3 Phone initiates call with IMS Core 1 Managed Backbone IQoS DOCSIS DSx CM and CPE Devices CMTS (PEP) © Cable Television Laboratories, Inc. 2010. All Rights Reserved. Proprietary/Confidential