P_HGI02715R02 HYBRID ACCESS. David Thorne, BT TSO HGI CLOSING SYMPOSIUM VENICE, MARCH 2016

Transcription

1 HYBRID ACCESS David Thorne, BT TSO HGI CLOSING SYMPOSIUM VENICE, MARCH

2 CONTENTS What is Hybrid Access? Business drivers Architecture options Access In-home Hybrid Access issues Hybrid Access work in the BBF Hybrid Access work in the HGI Overview of HGI SBI054 Summary and conclusions 2

3 What Is Hybrid Access? Hybrid access is adding a second, wireless (LTE) access connection to a wired (copper), Home Gateway Why? 1. Increase service availability 2. Provide higher Broadband speeds 3. Quicker service provisioning 3

4 4 Business Drivers for Hybrid Access 1. Increase service availability Broadband connectivity maintained when one access fails or is taken out of service (maintenance) - important for security, E-health, small businesses (POS terminals, Web servers...) 2. Provide higher Broadband speeds Augmenting slow ADSL lines to increase the footprint at a given (e.g. regulated) rate Augmenting medium-speed ADSL lines to support concurrent video streaming and browsing Augmenting a VDSL service to provide a higher, advertisable rate compared to a mobile only or VDSL only service Augmenting a VDSL service, where necessary, to increase the footprint at a given rate Augmenting a VDSL service to support multiple HD streams and fast browsing and download 3. Quicker service provisioning Provisioning a somewhat better broadband service before installation of an upgraded physical infrastructure has been carried out Most likely upgrade is ADSL>VDSL, but would the hybrid still be needed after the upgrade? If waiting for fibre, hybrid solution would not be needed, long-term

5 3 Architectural Choices Current solution: End to end - MPTCP between an end device and an MPTCP capable server. HHG is just an HG with a second WAN interface Wireless, LTE access HHG only HHG Internet MPTCP endpoint Wireline, xdsl access MPTCP aware server Wireless, LTE access HHG and HAG HHG HAG Internet Wireline, xdsl access 5

6 Full Hybrid Access Architecture Wireless, LTE access HHG HAG Internet Wireline, xdsl access 6

7 Hybrid Access Issues Charging QOS User policy input? Packet reordering Multiplexing technique HHG Additional functionality and interface US Traffic steering policy 1 or 2-box? Wireless, LTE access Differing, variable transport characteristics Combining management and diagnostics Wireline, xdsl access Network location Who owns and operates? Business model Scalability HAG DS Traffic steering policy Multiplexing technique Internet 7

8 HYBRID ACCESS WORK IN THE BBF - I Started mid 2014 Initial intention was a single TR covering Use Cases, architecture and nodal requirements for the HAG and HCPE Some pushback on the Use Cases and the role of existing solutions initial Study Document? First draft (WT-348) in November 2014 Leveraged other BBF policy and 3GPP-related FMC TRs (TR-134, TR-203, TR-291, TR-300) A lot of time was then spent on detailed tunnelling requirements Split into 2 WT-348 and WT-378 8

9 HYBRID ACCESS WORK IN THE BBF - II WT-348 Use Cases Architecture options High level system requirements WT-378 Nodal requirements (HAG and HCPE) Tunneling details Bonding of fixed broadband and 3GPP access paths Traffic distribution policies and mechanisms/algorithms Communication of traffic distribution policies to the HCPE and HAG Instrumentation and retrieval of access path metrics (capacity, state, etc.) WT-348 currently (March 2016) near end of Straw Ballot (final technical review) WT-378 not yet started 9

10 HYBRID ACCESS WORK IN HGI - I Also started mid 2014 Aware that the BBF was working on this topic Differences Looked at some of the topics that might have been in an SD More detail on the Use Cases, especially the increased bandwidth ones Critique of the BBF Use Cases Any missing Use Cases? Drivers from the perspective of the network operator and customer experience In-home architecture and issues Alternative, 2-box solutions MyFi and 4G phone hybrids Role and limitations of MPTCP Looked at other existing solutions Related path selection techniques to Use Cases No automatic assumption of 3GPP mechanisms, especially policy related Not considering detailed HAG requirements, network metrics etc. i.e. the pure Access aspects 10

11 HYBRID ACCESS WORK IN HGI - II Possible outcomes External Influence the BBF Use Cases and hence WT-348 Internal High-level business (SBI) requirements for Hybrid Access Nodal requirements for the HHG Fall-back case already included in the Residential Profile Current Status Published HGI-SBI054 - Use cases and architectures for hybrid access 11

12 SBI054 OVERVIEW Use Cases End to end architecture In-home architecture 1 and 2 box solutions Multiplexing options Policy examples Role of MPTCP High level business requirements Service provider Hybrid Access considerations 12

13 IN-HOME ARCHITECTURE Initial presumption was that the HHG (HCPE) was a single box, an enhanced version of today s HG Second WAN interface Path selection, muxing, demuxing Re-ordering Policy. HGs are often located to optimise in-home WiFi coverage, typically fairly centrally LTE reception would be better near a window, or may need an external antenna This would compromise WiFi coverage, and might even reduce the hybrid access bandwidth advantage Could have a separate LTE modem 2-box solution. 13

14 1 OR 2 BOXES IN THE HOME? 1 box 2 box Pro Pro More acceptable to the customer general dislike of multi-box solutions Does not take up one of the existing LAN interfaces (Ethernet, USB) Facilitates unified management and diagnostics Allows optimum positioning for Wi-Fi coverage and LTE reception May not need HG change-out but firmware upgrade still needed (mux/demux, path selection) Con Con Can be used by converged and non-converged operators No standards for a Hybrid HG Totally new box (needs new hardware) Needs higher processing capability Compromises Wi-Fi coverage and/or received LTE signal strength Customer dislike of multi-box solutions May occupy one of the existing LAN interfaces (Ethernet, USB) May need to use Wi-Fi as a WAN interface Harder to provide unified management and diagnostics May need an external (to the house) antenna and new co-ax to the HG 14 Only suited to a converged operator

15 ROLE OF MPTCP Pro Defined (IETF RFC 6824, IETF RFC 6356) Implemented Can be implemented end-to-end avoiding deployment of a new network element (HAG) Works on a per application basis, so can perform dynamic, per application steering. Con Current implementations do not exploit MPTCP s full potential Simple implementations may not provide significant advantages over regular TCP Policies need to be created and tuned by the Operator. No standard to help. Requires 2 IP addresses Jitter and latency will be greater than that of the highest of the 2 paths Only works for TCP Works on a per app basis so more granular steering, e.g. per stream per app, difficult Protocol not designed to increase total bandwidth 15

16 PATH SELECTION OPTIONS 16 Single path at any one time Failover Per session Best path, sub-session Per device Dual path, aggregate Per application Per stream Per packet Per device

17 PATH SELECTION ISSUES 17 Per packet The different paths will have different latency and loss will get packet re-ordering > need sequence numbers The effective latency will be greater than either individual path These will have an adverse impact on TCP performance Per Stream Need to make the decision before the stream starts Avoids any glitching due to a switchover Per application Application has to be aware of multiple paths At least some Use Cases do require packet-based muxing But this may be undesirable for streaming and latency sensitive applications. Strong pushback from the IETF on packet based muxing

18 PATH SELECTION POLICY 18 There are 2 distinct ways of doing selection (Semi) Static must be able to take inputs from the service provider and end-user Dynamic based on network state what are the appropriate network metrics? how are they measured? how often are they measured? where do they need to be communicated between? how are they communicated? Some policy examples Specific types of service always use a certain path (voice, gaming) Use path A until it is full Use lowest cost path

19 GUIDANCE FOR SERVICE PROVIDERS Really need to understand which Use Cases you want to address this can have a significant influence on the solution Is Hybrid Access a mass-market solution or a niche play? One or two box in-home solution? HAG or single ended architecture? Architectural and business impacts of the HAG The need for policy definition and dissemination 19

20 SUMMARY AND CONCLUSIONS Hybrid Access is not simple There are already solutions out there standard and proprietary - albeit with some limitations If better, standardised solutions are going to be developed/deployed, need to understand the real Use Cases, business drivers and customer experience impacts This will effect things such as LTE network capacity and coverage, multiplexing techniques, policy, network performance monitoring SBI054 provides a lot of background, discusses the issues, and gives general guidance WT-348 provides the next level of system requirements But significant work remains to be done in the areas of multiplexing, policy, policy dissemination and network metrics this is the proposed focus of WT