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Network Convergence of Mobile, Broadband and Wi-Fi

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A presentation and video by Ben Toner, Founder & Director, Numerous Networks exploring the convergence of Mobile, Broadband and Wi-Fi

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Network Convergence of Mobile, Broadband and Wi-Fi

  1. 1. Exploring the convergence of Mobile, Broadband and Wi-Fi Brought to you by www.numerousnetworks.co.uk ben@numerousnetworks.co.uk • What is Convergence and why do we need it • 3GPP ATSSS • Other convergence options • How do you try it today • The modes of convergence Network Convergence November 19 1 Numerous Networks provides consultancy and technical services to help anyone who wants to use Wi-Fi as a serious mobile offering and get the best experience out of their infrastructure. That involves ensuring Wi-Fi services are ready for mobile use while providing options to converge Wi-Fi, cellular and broadband together for the best uninterrupted user experience. Numerous Networks have been enhancing the user experience of carrier grade Wi-Fi for more than 10 years.
  2. 2. The Need • BT are one of the largest companies to state the importance of convergence in their strategy November 19 2 “Seamless, consistent connectivity ” – Howard Watson, CTIO BT
  3. 3. The overall objective is to converge an user’s experiences into a single expected experience. • Network convergence is part of the required technical approach • Primary network modes • Home Wi-Fi / Office Wi-Fi / Public Wi-Fi • Cellular • Transitionary network modes • Leaving Home Wi-Fi to use a cellular connection • Arriving at the Office Wi-Fi from a cellular connection • Stepping into a coffee shop and using public Wi-Fi • Failure Modes • Filling in congested (slow) Home DSL backhaul with fast 4G cellular • Filling in slow public Wi-Fi with fast 4G cellular • Supplementary network modes • Adding cellular to slow Wi-Fi to create a minimum speed • Add cellular to DSL backhaul to deliver a minimum public/private Wi-Fi • Service differentiating network modes • Local firewalled / VPN’d network for internal enterprise data • Public network to connect to secure enterprise cloud Predictable service at a predictable cost It should not cost me more than I expect I should not have to know (or care) about what I am connected to It should always (typically) perform to a minimum standard which I am paying for What is causing the need November 19 3
  4. 4. Start services at home on Wi-Fi Drive away: Weak Wi-Fi = bad app experience 1 2 Convergence solves this problem The role of convergence for everyday network issues November 19 4
  5. 5. What is Convergence The use of Multiple Networks The Simple Description Home Wi-Fi Public Wi-FiPublic Cellular Private Cellular To deliver a Combined or Converged Network Capable of providing the end user with access to the Data Network at a quality level which they expect November 19 5
  6. 6. Defining Documents A sample of the bodies defining and standardizing the next generation of convergence Recommended Read A great summary directed towards supporting broadcast and multimedia http://5g-xcast.eu/wp-content/uploads/2019/07/5G- Xcast_D4.2_v3.0_web.pdf Convergence Standardisation Bodies November 19 6
  7. 7. Defining Documents ATSSS is optional and has a preliminary specification + Technical Report to guide the evolution Convergence in 3GPP Initial Specification allows ATSSS to be implemented using MP-TCP as it has some adoption. e.g. Apple Technical Report suggests many more convergence options. TBD what happens here Some OTT solutions might disrupt here too November 19 7
  8. 8. Mobile Device Convergence Steering in ATSSS November 19 8 Network Wn Network W2 • Using multiple networks needs to be simple to the end user; • all the complexity of selecting the network and managing the choice of network for the data is automatically handled • according to some governing rules or requirements • made by the device or the network or both Network C1 Quality Assessment Data Path Decision Network W1 Quality Assessment User Preferences Service Provider PreferencesNot noticed by the end user Industry term The procedure for selecting an access network for a new data flow is known as ‘steering’ the connection Traditionally Wi-Fi OR Cellular 8
  9. 9. Mobile Device Convergence Switching & Splitting in ATSSS November 19 9 • There is an increasing trend to use multiple connections at the same time to achieve an experience target; • No drops. Moving a data flow from one network to another without interruption • Quick responses. Using multiple networks and selecting the response which comes back quickest • More data. Using multiple networks at the same time to increase the bandwidth • Load balancing. Choosing the network which is least contended / congested Industry term The procedure of moving an ongoing data flow from one access network to another is known as ‘switching’ the connection Network Wn Network W2 Network C1 Quality Assessment Data Flow / Packet Decision & Direction Network W1 Quality Assessment User Preferences Service Provider Preferences Industry term The procedure of splitting the traffic of an ongoing data flow across multiple access networks is known as ‘splitting’ the connection
  10. 10. 3GPP define the Multi-Access Packet Data Unit (PDU) • The Multi-Access PDU enables the concept of using multiple network access paths to transfer data from a single data source (such as an application) • It is fundamental to all multipath approaches Virtual Interface NG-RAN UPF-2 (optional) UPF-1 (optional) UPF-A IP 5G WL AN Child PDU session #1 UE N6 AMF N2 N2 N3 N3 SMF N4N11 WLAN AN N3IWF Child PDU session #2 Multi-Access PDU session Multipath PDU as defined by 3GPP R16 in 23.793 A MA PDU Session may be established either: a) when it is explicitly requested by an ATSSS-capable UE; or b) when an ATSSS-capable UE requests a single-access PDU Session but the network decides to establish a MA PDU Session instead. Key Concept for Convergence November 19 10
  11. 11. ATSSS Technical Report TR 23.793 extending the support for Steering, Switching, Splitting However, 23.793 Technical Report proposes Multipath Convergence could take one of the following options 1. NULL tunnel (IP flow steering) 1. All packets from the same flow are sent on the same access (based on 5-tuple) 2. GRE tunnel 1. Both access types can be used at the same time over individual tunnels 3. Trailer based L3 Generic Multi-Access (GMA) 1. Trailers used to allow for packet ordering when using multiple access 4. User Plane Convergence using L4 multipath 1. MP-TCP 2. QUIC / MP-QUIC 3. SCTP 4. UDP Generic 23.50x R16 specifies only one higher layer option which is MP-TCP. Low Layer steering is also defined as ATSSS-LL but no additional protocol is applied Only MPTCP specified in R16 Can currently only be NULL tunnel Other IETF protocol will be allowed but none are ready November 19 11
  12. 12. Practicalities • MPTCP is a higher layer multipath protocol which works for TCP flows only. • It can be difficult to schedule traffic in order to avoid head of line blocking • Other methods such as MP-QUIC aim to remove these difficulties and also support all traffic types • Some non-TCP applications cannot fall back to TCP and will not benefit (e.g. some real time voice/video) • ATSSS- Lower Layer is suitable for steering and switching flows of any type • It applies no additional protocol so could only be used for steering (today) and maybe switching in the future • It is required for all ethernet PDU types • Something similar is available TODAY on some broadband / LTE hybrid home equipment • And as over the top applications on smartphone devices. (They currently need to use the VPN service on the UE to capture all the traffic) • No mention of dual 3GPP Access – Private LTE (e.g. CBRS) + Public LTE • Even where the device has 1 radio, the use case for seamless handover in a Dual-Sim Dual-Standby (DSDS) environment is important for offload continuity 3GPP R16 ATSSS and the practicalities November 19 12
  13. 13. Broadly based on Generic UDP L4 convergence • These challenger solutions are implementing a proprietary UDP approach to perform aggregation • There are 3 deployment models • On mobile devices there are two integration methods • SDK integrated into an application, acts similar to an L4 aggregation such as MPTCP or MPQUIC • Whole device aggregation using the VPN service to capture traffic. All applications see a virtual IP address of the aggregation tunnel to the aggregation server (equivalent to ATSSS) • For Home Gateways and Access Points an SDK exists which can be integrated into the network stack • All traffic types can be supported • New congestion control is implemented to optimise the use of the links and has been empirically tuned to suit the varying latencies between Wi-Fi and Cellular networks • Enhancements such as Forward Error Correction are already in use in these solutions • Up to date encryption can be used (but will be an overhead) • Provides all the desired aggregation modes and is already tuned for mobile behaviour • Offers out of box redundancy and gapless handover for real time media streams (e.g. IP calling) • Offers aggregation to achieve a minimum bandwidth while preferring a primary low cost access when available. Other non-standardized challenger solutions November 19 13 Any application traffic Captured by VPN Proprietary Congestion Control / re-ordering scheme / packet- access assignment / FEC / encryption Dual IPSEC tunnels Single virtual interface
  14. 14. Multipath TCP From Tessares; a major contributor to the MP TCP IETF RFC Multipath QUIC From Quentin De Coninck; a major contributor to the MP QUIC IETF RFC Source Code Proprietary UDP From Connectify; The largest distributed public over the top application Implementations available to try user plane convergence on your own mobile device – today! ATSSS future (as defined in TR23.793) expects to allow for any one of these options: User Plane Convergence Method using L4 Multipath Solutions (MP-TCP, QUIC, MP-QUIC, SCTP, UDP generic) November 19 14 Various other proprietary UDP solutions exist
  15. 15. Using rules to manage ATSSS • After the establishment of a MA PDU Session, the UE receives a prioritized list of ATSSS rules from the SMF Structure of the ATSSS rule • Traffic steering policy: This rule is used to select an access when initiating a new data flow. • Traffic switching policy: This rule is used to determine when a data flow should be moved from 3GPP to non-3GPP or vice versa. • Traffic splitting policy: This rule is used to determine when a data flow should be split across 3GPP and non-3GPP. November 19 15
  16. 16. How performance is measured and governed measures which feed into rule set PCF (Policy) sets rules Loss, Latency, Jitter Measures Traffic distribution based on ensuring no packets get out of order Performance Management Function • Requires measurement and reporting of Packet Loss, Jitter, RTT • Need careful combination to avoid rapid switches and bad decisions November 19 16
  17. 17. Networks are combined to provide a user experience target which includes stability or consistency of the connection, perceived minimum speed and optimisation of cost to the end user and service providers Tech Capture 3GPP description of convergence options. Part 1 Steering Mode = Active-Standby MA-PDU Session Non-3GPP Access 3GPP Access Data flows to be sent over the MA-PDU session Active Standby Steering Mode = Priority-based Non-3GPP Access 3GPP Access Data flows to be sent over the MA-PDU session MA-PDU Session Overflow traffic High Priority Low Priority Typical fallback scenario such as a home broadband router. The primary access is preferred unless it is failing Certain traffic types are assigned to a priority network. Fallback to a low priority access occurs of there is performance impairment November 19 17 Modes of Convergence - 1
  18. 18. Combination options exist to handle multiple use cases where traffic can be overflowed or copied onto an alternative network Tech Capture 3GPP description of convergence options. Part 2 Steering Mode = Best-Access Non-3GPP Access 3GPP Access Data flows to be sent over the MA-PDU session MA-PDU Session Best access Overflow traffic Steering Mode = Redundant Non-3GPP Access 3GPP Access Data flows to be sent over the MA-PDU session MA-PDU Session When the user choice may not matter (e.g. unlimited data plan) Use best network (e.g. smallest delay) and overflow to secondary to ensure minimum service quality All traffic copied. Rare but found today in some over the top applications offering gapless handover. The redundancy is generally only happening during a transition period when the primary network quality is below standard November 19 18 Modes of Convergence - 2
  19. 19. More networks = more opportunities to provide a quality of service to the customer while balancing the load between networks. Tech Capture 3GPP description of convergence options. Part 3 Steering Mode = Load-balance MA-PDU Session Non-3GPP Access 3GPP Access Data flows to be sent over the MA-PDU session 50% 50% Data is split between the access on a percentage basis (only suitable for non-GBR flows) November 19 19 Modes of Convergence - 3
  20. 20. MPTCP Scheduling and the importance of head of line blocking mitigation http://blog.multipath-tcp.org/blog/html/2014/03/30/why_is_the_multipath_tcp_scheduler_so_important.html DT slides on convergence testing experience https://mailarchive.ietf.org/arch/msg/banana/Z6ch6F50ICL8E5DKEox2Qcw-yl4/2 Links November 19 20 Huawei's GRE Tunnel Bonding Protocol (Informational) https://tools.ietf.org/html/rfc8157 Generic Multiple Access (GMA) Convergence (Informational) https://tools.ietf.org/html/draft-zhu-intarea-gma-04 https://datatracker.ietf.org/wg/mptcp/documents/ https://tools.ietf.org/html/draft-deconinck-quic- multipath-03 Recommended Reads 5G X Cast A great summary directed towards supporting broadcast and multimedia http://5g-xcast.eu/wp-content/uploads/2019/07/5G- Xcast_D4.2_v3.0_web.pdf https://www.itu.int/rec/T-REC-Y.3130-201801-I/en https://www.broadband- forum.org/technical/download/TR-348.pdf https://www.broadband- forum.org/technical/download/TR-378.pdf https://portal.3gpp.org/desktopmodules/Specificatio ns/SpecificationDetails.aspx?specificationId=3254

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