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Cross-Layer Optimization (CLO)
Problem Statement
Young Lee, Susan Hares, Greg Bernstein
Page 2
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 3
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 4
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 5
Application Service ProfilesCharacteristics & 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 6
File/Content Distribution SystemsDownload 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 7
Content Distribution Network (CDN)
Surrogate
Surrogate
Surrogate
CE
CE
CE
User User
User User
User User
CE CE
CE CE
CE CE
PEPE PE
PE
PE
PE
DNS server(ANC)
TNC Transport NetworkService request
CDN NetworkDNS 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 8
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 9
Video On Demand
ContentSource
SuperHead
End (SHE)Location 1
SuperHead
End (SHE)Location 2
ContentDistribution
Local AreaHead End
1
End User
PEPE
PEPE
Local AreaHead End
2
End User
Local AreaHead End
3
End User
PE
CE
CE
CE
CE
CE
VoD ServiceController
(ANC)
ApplicationCloud
• 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. VNT3. Reserve
3. Download request
ANC – Application Network ControllerTNC- Transport Network Controller
Page 10
Conferencing and GamingThese 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 11
Video Conferencing Architecture
Meeting RoomSource
CE PE
Meeting RoomDestination 1
Meeting RoomDestination 2
Meeting RoomDestination 3
CE
CE
CEPE
PE
PE10 Mbps
30 Mbps
Meeting RoomDestination 4
PE
CE
Video ConferencingController
(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 ControllerTNC- Transport Network Controller
Page 12
Video Gaming Service Architecture
GameServer
GameServer Game
ServerCE
CE
CE
Gamer Gamer
Gamer Gamer
Gamer Gamer
CE CE
CE CE
CE CE
PEPE
PE
PE
PE
PE
Video GameController (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 ControllerTNC- Transport Network Controller
Page 13
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 14
Problem StatementThe 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 15
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 16
SNMP Example
CECE
PEPE NetworkIngress
NetworkEgress
Data path
BridgeMIB L2 Core
Transport Network
L2
ApplicationSource
ApplicationSource
End PointConsuming ResourceEnd Point
Consuming Resource
ApplicationSource
L2VPLSMIB- PE
L2VPLSMIB-
BridgeMIB
BridgeMIB
L2VPLSMIB-
TransportMIB
TransportMIB
TransportMIB
Roll-forward, Roll-back
For massive data or time critical
Implies synchronization or
Atomic handling
Potential Solutions
Page 18
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 19
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 3rd party “broker”
CLO functionsCLO functions
CLO Entity
CLO Entity
3rd PartyBroker
Page 20
Generalized Data Path Connectivity (Single Domain)
CECE
PEPE NetworkIngress
NetworkEgress
Data path
Core Transport Network(L1 or L2 or L3/MPLS-TE)
CLO Functions
ApplicationSource
ApplicationSource
End PointConsuming ResourceEnd Point
Consuming Resource
Page 21
Multi-Layer, Multi-Device, Multi-Domain Scope of CLO
Carrier 1IP L3 Based
Carrier 2L2/SPBB Based
Carrier 3 OTN/WDM
Application
WDM (ROADM) OTN/WDM
Multi-Domain Adaptation and Translation
Cross Layer Communication
Page 22
Summary – Proposal to IETFCreate 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 23
Thank You