Cross-Layer Optimization (CLO) Problem Statement Young Lee, Susan Hares, Greg Bernstein

Page 1 Cross-Layers Application Layer (Host Layer) Distributed Resources: servers, content, data sets, computing power, cache/mirror Uses Network Resources Different QoS requirements for each application Transport to Network Layer Bandwidth, Connections, Links, Connection Processing (Creation, Deletion, Management) Admission Control, Resource Reservation Applications uses resources in IP, MPLS, and/or Optical Transport Networks, Layer 2 Transport Layer Network Layer Application Layer

Page 2 Applications need Assured performance levels associated with the application. Optimized resource utilization via cross-layer interaction between application and network layers, A cross-layer management paradigm that is dynamic, interactive, elastic, adaptive, and flexible across application-network layers. ›Elastic – stretches the network during growth ›Adaptive – changes with network

Page 3 Current and Emerging Application Resources Live Data Sources ›Video or audio from live sporting or entertainment events, data feeds from radio telescopes, remote medical surgery Processing Resources ›Raw computational capability for cloud computing, transactional capabilities for e-commerce, processing for streaming media, transcoding capabilities for video and audio, etc... Storage Resources ›Disk farms, tape libraries, etc... Content/Data Sets ›Video, audio, commercial, scientific, etc...

Page 4 Application Service Profiles Characteristics & QoS Requirement of application service from a network perspective: Location profile : locations of both the clients and the sources QoS profile : (i) Delay Tolerance Bound; (ii) Jitter Tolerance Bound; (iii) Packet Delivery Ratio Tolerance; (iv) Network Availability, etc. Connectivity profile : (i) P-P; (ii) P-MP; (iii) MP-MP; (iv) Any Cast Directionality profile : (i) uni-directional; (ii) bi-directional Bandwidth profile : Maximum, average, and minimum bandwidth requirements for the connectivity, maximum burst rate, maximum burst duration, etc. Duration of service profile : service time of the application Network media profile : (i) optical only; (ii) no microwave, etc. Restoration profile : (i) Reroute required; (ii) do not re-route, etc. Security profile : (i) dedicated end-to-end VPN-like resource allocation; (ii) dedicated physical resource allocation Communicate these application profiles to network via a common mechanism between application and network layer

Page 5 File/Content Distribution Systems Download of images/audio/video/software via the network; Common optimization problems in this system includes: Cache and Mirror placement problem ›Coordination of the application and network (transport and IP) topological information is key to optimization Efficient transfer of content to servers ›Coordinated point-to-multipoint concurrent path optimized with network loading condition in both application and network is key to optimization Client to server assignment problem ›Current server load and network latency between client and server are key QoS

Page 6 Content Distribution Network (CDN) Surrogate CE User CE PE DNS server (ANC) TNC Transport Network Service request CDN Network DNS server performs the ANC function. It receives users’ requests Based on surrogate’s availability, transport network resource and user’s position, it chooses the best surrogate to serve the user. It sets up a PE-to-PE connection between the surrogate and the user through communication with the TNC in the transport network. The users who share the same surrogate and the access PE can share the PE-to-PE connection. B/W modification capability is also needed

Page 7 Streaming Content Distribution Systems The streaming case increases the need for coordinated multi-layer monitoring and configuration primarily due to more stringent QoS constraints on bandwidth and jitter. Optimization problems for a live streaming service include: ›Server selection and placement problems (application based multi-cast) ›Leaf attachment problem and tree construction (network-based multi-cast) Additional optimization decisions required with on-demand streaming ›Client stream sharing ›Batch or multicast server selection problem

Page 8 Video On Demand Content Source Super Head End (SHE) Location 1 Super Head End (SHE) Location 2 Content Distribution Local Area Head End 1 End User PE Local Area Head End 2 End User Local Area Head End 3 End User PE CE VoD Service Controller (ANC) Application Cloud VoD Service Controller (VSC) performs the ANC Function Local Area HE sends a query the VSC for video download VSC makes a decision which SHE should send the video to the Local Area HE based on: Transport Network Topology (that TNC provides) and Server (SHE) status and Movie Availability QoS: Delay and Jitter sensitive Connection: One-way 1. service request Transport Network TNC 2. VNT 3. Reserve 3. Download request ANC – Application Network Controller TNC- Transport Network Controller

Page 9 Conferencing and Gaming These applications increase the complexity of the overall application connectivity and the need for cross-layer coordination of monitoring, configuration. Bi-directional connections and asymmetric bandwidth between the server and the user location Multipoint-to-multipoint connectivity with hard QoS constraint on latency and bandwidth ›Data path formation and reformation for MP-MP can be very inefficient without considering the underlying network resources ›Network path computation and path reservation may be required to ensure the end- users service objective. Gaming adds additional scalability on QoS requirement and the connectivity.

Page 10 Video Conferencing Architecture Meeting Room Source CE PE Meeting Room Destination 1 Meeting Room Destination 2 Meeting Room Destination 3 CE PE 10 Mbps 30 Mbps Meeting Room Destination 4 PE CE Video Conferencing Controller (ANC) Video Conferencing Controller (VCC) performs the ANC function. It receives client requests It sets up the P-MP connections via the TNC in the transport network QoS: Delay and Jitter sensitive Connection: Asymmetric P-MP connections (uplink: 10 Mbps; downlink: (N-1)*10 Mbps where N is the number of participants) Desk Top conferencing is envisioned to connect 100’s of clients which will require higher B/W. Service request TNC ANC – Application Network Controller TNC- Transport Network Controller

Page 11 Video Gaming Service Architecture Game Server Game Server Game Server CE Gamer CE PE Video Game Controller (ANC) TNC Transport Network Service request Video Game Controller (VGC) performs the ANC function. It receives client requests It sets up the P-P connections via the TNC in the transport network Server location and B/W availability from Server to Client are key info for decision B/W modification capability is critical QoS: Delay and Jitter sensitive Connection: Asymmetric P-P/MP-MP connections (uplink: 100 Mbps; downlink: 10 Mbps) Up to 100,000 clients connections (E.g., Worldwide war games) ANC – Application Network Controller TNC- Transport Network Controller

Page 12 Grid Computing/Remote Medical Grid computing supports extremely large transfers of files and streaming data. The volume of the traffic makes it critical to synchronize changes to application and network. Key issues with Grid Computing include: ›Instantiation of the connectivity with high data rates (100’s Gbps) and/or data set size (1000’s) ›Controlling very high speed network Remote medical application adds more complexity over Grid Computing in that it requires fast setup of 100Gbps level of connectivity with higher security and more stringent jitter requirements including MP- MP connectivity. Lambda-level optical transport with control plane would be required with a sophisticated path computation algorithm across layer. (Optical Bypass application)

Page 13 Problem Statement The lack of common coordination mechanism between the application and each of the layers in the “network” does not allow coordinated cross-layer optimization: Coordinated “query” of application and network requirements to determine available computing and network resources (including resource availability and demand as a function of time); Coordinated provisioning processes (resource reservation) of both application and network layers based resource availability on both layers (statistical and/or real time); Coordinated cross-layer monitoring; and Quick re-optimization based on policy of the application/network upon churn

Page 14 Existing Solutions Only Provide Partial Solutions IETF Management solutions: SNMP, Netconf/Yang, ›Do not provide the necessary context to view across multiple layers, multiple devices/technologies. ›Lack of a context that allows synchronization of actions for read-view, write-view, notify-view and actions. MPLS OAM ›MPLS OAM is limited to MPLS device. The current scope of MPLS OAM does not support non-MPLS devices for its configuration and provisioning functions. ›Lacks topology sharing and configuration interface. ITU-T Y.2011/2012 ›Defines application network interface (ANI); however, it does not address any details on cross-layer synchronization of information, configuration and provisioning IETF ALTO WG ›Current scope does not address the multi-layer synchronization problems ›Does not provide the mechanism to configure/re-optimize and provision across layers.

Page 15 SNMP Example CE PE Network Ingress Network Egress Data path Bridge MIB L2 Core Transport Network L2 Application Source Application Source End Point Consuming Resource End Point Consuming Resource Application Source L2VPLS MIB- PE L2VPLS MIB- Bridge MIB Bridge MIB L2VPLS MIB- Transport MIB Transport MIB Transport MIB Roll-forward, Roll-back For massive data or time critical Implies synchronization or Atomic handling

Potential Solutions

Page 17 Cross-Layer Optimization Functions (Enablers) CLO functions: To exchange network capabilities (Network Capability Exchanges) To initiate service instantiation of application to network with profile exchange (Provisioning) To exchange topology and/or traffic- engineering related information between the layers (Coordination of cross-layer D/B’s for joint optimization) To exchange application/network congestion/failure information (Coordination of configuration changes) CLO functions

Page 18 Information sharing and CLO entity ownership Information to be shared across layer depends on CLO ownership ›CLO by application provider  Sharing of some type of topology information ›CLO by network provider  sharing of some type of application information ›Other possibilities include neutral 3 rd party “broker” CLO functions CLO Entity 3 rd Party Broker

Page 19 Generalized Data Path Connectivity (Single Domain) CE PE Network Ingress Network Egress Data path Core Transport Network (L1 or L2 or L3/MPLS-TE) CLO Functions Application Source Application Source End Point Consuming Resource End Point Consuming Resource

Page 20 Multi-Layer, Multi-Device, Multi- Domain Scope of CLO Carrier 1 IP L3 Based Carrier 2 L2/SPBB Based Carrier 3 OTN/WDM Application WDM (ROADM) OTN/WDM Multi-Domain Adaptation and Translation Cross Layer Communication

Page 21 Summary – Proposal to IETF Create an IETF WG to: Define Cross-layer optimization functions and architecture Develop protocols that would enable: ›Information Exchange between Application and Network Layers  Topological and TE (Virtual/Abstract) view of each layers to be exchanged per query  Monitoring data exchange ›Allow the Application Layer to request for a path estimation (path feasibility) to Network Layer ›Allow the Application Layer to initiate a provisioning connection/flow to network layer ›Multi-layer, multi-technology adaption and translation ›Potential multi-domain

Page 22 Thank You