Multiservice Edge Architectures and Solutions for Service ...faculty.ccc.edu/mmoizuddin/CISCO LIVE 2008/AGG/BRKAGG-2001.pdfMPLS/IP Integrated Services Core Content Farms VOD TV SIP
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This session presents design options for centralized and distributed multiservice broadband network architectures that scale to tens of millions of subscribers and bandwidths up to 100 Mbps per household. The session introduces popular triple-play broadband aggregation architectures. The advantages and disadvantages of the different architectures in terms of bandwidth scalability, policy plane scalability, failure radius, traffic patterns, service flexibility, and more is then discussed. Attendees learn to identify the architectural trade-offs between centralized and distributed broadband architectures, and which criteria should be used in an architectural evaluation.
(35€)50 TV channels1000 VoDTime-controlSecondary phone with unlimited metropolitan callsVoice mailUp to 18Mbps / 800 Kbps internet5 email accounts Web page Parental control
Understanding Where Broadband Is GoingCurrent European SP Multimedia Service Offerings
It is time to revisit some operational assumptions…
Formuleinternet+TV+téléphone
Alice Home TV InternetPlusBellen Lite + Interactieve TV
Deutsche Telekom
(49€)VoD w/ 1700 titles70 TV channelsEPG, NW-VCR,Up to 16Mbps Flat rate InternetVoice with SMSFree 2nd phone number (VoIP)Hotspot flat rate
Single-Edge vs. Multi-Edge ServicesSingle: all services destined to the same subscriber flow through one edge system, forming an integrated policy enforcement point
Multi: services destined to the same subscriber do not flow through one edge system.
Centralized vs. Distributed EdgeCentralized: Edge systems are concentrated in few IP PoPs and are connected to access nodes via an aggregation network.
Distributed: Edge systems are dispersed in many IP PoPs close to the subscribers and may even be co-located with the access nodes
Clustered vs. UnclusteredUnclustered: Allocating all subscribers for a particular service to one system
Clustered: Allocating the subscribers to a particular service over many systems located in the same PoP
Goal is to minimize overall Total Cost of Ownership (TCO) related to the deployment and operation of a broadband aggregation network delivering quad-play servicesMin Σ Capex(services, time) + Σ Opex(services, time)
s.t. Traffic flows <= Link CapacityTraffic flows <= Node capacityNode Capacities >= Number of subscribers….
Note: not just minimization of initial Capex at time t=0!Also minimization of Opex and expansion Capex
Assumes a timeframe tNeed to take subscriber and traffic growth into account
Network equipmentBNG, DSLAMs, PON…
Servers for each serviceSIP, RACS, RADIUS, Softswitches, Gateways…
0.9 Mbps / sub 10 Gbps Engine2.75 Mbps / sub 20 Gbps Engine5.1 Mbps / sub 160 Gbps Engine
Scalability—Bandwidth per Subscriber
Multimedia traffic impacts subscriber scalability per system
Bandwidth per subscriber increases from ~200 Kbps/sub for traditional Internet to 1-6Mbps/sub for multimedia servicesModels assume different service concurrency rates for Voice / Video / TV / Internet
Fixed-Mobile-Convergence place substantial additional scalability demands on systemsCentralized single-edge architectures reach scalability limitsClustered, multi-edge or distributed architectures offer better architectural scalability
Control plane functions are harder to architect than forwarding plane functions!Multi-edge requires multiple policy control messages to different network nodes Single-edge architectures benefit from single policy enforcement point
Policy enforcement communication efficienciesSingle authentication and authorization for all services at the policy enforcement pointMultiple services can be activated / de-activated in a single RADIUS CoA message with ISGBut: Centralized sing architecture needs to maintain a vast amount of state information per subscriber
Distributed Architecture benefits from Policy enforcement close to subscriber
A-RACF: Access Resource & Admission Control FunctionSPDF: Serving Policy Decision Function
Network Attachment Sub-systemCLF: Connectivity Session Location Repository FunctionCNGCF: Customer Network Gateway Control Function NACF: Network Address Configuration Function UAAF: User Authorization & Authentication Function
PDBF: Profile Database Function
Service SubsystemsP-CSCF: Proxy call session control functionI/S-CSCF: Interrogating / service call session control functionIBCF: Interconnecting Border Control FunctionUPSF: User Profile Serving Function
Centralized architectures rely on transport tunneling mechanisms in the aggregation network
VLAN / Tunnel scalability needs to be taken into accountMapping of VLANs to services: per-DSLAM VLANs, per-service VLANs, customer VLANs…
Tunnel scalability limits may be mitigated using clustering or multi-edge architectures.Distributed architecture can leverage self-organizing, self-healing IP / MPLS backhaul
Equivalent to core IP/MPLS (e.g. with MPLS VPN)Reduction in SP managed objects (e.g. EVC crossconnects, pseudowire tunnels)
High-bandwidth multimedia traffic is a standard service offering and must thus be considered by all architecturesBackhaul & Client-Server traffic is invariant to the different architectures
Policy enforcement close to subscriber may save backhaul bandwidth
Multicast traffic is efficient if replication happens close to the subscriber Saves bandwidth in the aggregation networkFavors multi-edge or distributed architectures
Traffic local to a BRAS can be handled more efficiently by distributed architecture
Optimized Routing for peer-to-peer routingLocal Video CachingService Interconnection to PSTN?Important for mobile traffic patterns!?BRAS IP Address allocation already supports this
P2P applications (e.g. Skype, BitTorrent, Gnutella) have been main contributors to bandwidth growth in past years
Need to differentiate between P2P Downloads and P2P live streaming
P2P changes communication patternsPotential to keep more traffic localTraffic downloaded from closest users
But: so far, little empirical evidence how much traffic remains geographically local IP addresses carry no geographical significance -> different administrative domains
P2P overlays now considered for live video streaming (Coolstreaming, PPLive)
Flash crowd streamsChinese spring festival with up to 225K concurrent users @ 300 Kbps
Algorithm similar to BitTorrentStreaming server acts as source root Joining peer receives candidate list of peers who are able to stream (e.g. 50 peers)Joining peer then selects subset based on RTT (e.g. 5 peers) and receives buffer maps with streaming segmentsUpdated membership information continuously exchanged between peers to communicate state changes.Requested streaming segments received in both push & pull mode into receiving application buffer
Differentiation between IPTV and Internet TV using over-the-top distribution
IPTV: SP video streaming over closed IP networks
Source: HeavyReading, “Internet TV, Over-the-Top Video, & the Future of IPTV Services”, Vol. 5, No. 10, June 2007
Increasing requirement for value added servicesVoIP and Video services motivate SBCsApplication-aware services motivate DPI technologies, e.g. Most P2P traffic can no longer be identified at layer 4Security services gaining popularity
Single-edge architectures have more flexibility for quad-play servicesPay-as-you grow: incremental service roll-outIntegrated services could be realized either with service-blades or built-in
Distributed architecture more conducive for wholesaleFacilitates local wholesale modelL3VPN-based business or wholesale servicesPseudowire L2VPN services for business or wholesaleStill there are shared segments (QoS) in getting to the customer
Session Border Controllers (SBC) are critical to enable rich media video telecommunications across networks with simultaneous support for voice/video/data
SBC enables direct IP to IP Interconnect between multiple Administrative Domains for Session-Based Services:
Flexible Packet MatchingStateless packet matchingXML-based traffic description (protocol header description files)Can match on protocol stack, bit pattern, header fields
Network Based Application Recognition (NBAR)Identifies over 90 applications and protocols TCP and UDP port numbersStatically assignedDynamically assigned during connection establishmentNon-TCP and non-UDP IP protocolsData packet inspection for matching values
• Upstream anddownstream per ISP aggregate per class
- police
• No QOS required
BRAS/NPE Hierarchical QOS
SVLAN
SVLAN
• SVLAN shaping with sum of shaped rates allowed to exceed interface rate
• Configured by CLI
• Subscriber line level shaping• Sum of shaped rates can exceed SVLAN rate• Priority propagation for voip and video traffic• Configurable share of remaining bandwidth • Configurable overhead accounting• May be configured via CLI or using dynamically using RADIUS
For PPPoX sessions terminated on the active route processor (RP):1. PPPoX session information is synchronized to standby RP 2. If active RP fails, PPP sessions become active on standby RP3. ATM virtual circuits and PPPoX session IP addresses maintained as they were before
on the primary RP
Works with NSF (OSPF, IS-IS, BGP)Supports In-Service Software Upgrades (ISSU)Up to 32,000 PPPoX sessions supported
For L2TP sessions terminated on the active route processor (RP):1. L2TP control channel information is synchronized to standby RP (e.g. tunnel ID,
sessions IDs, data sequencing status etc) 2. If active RP fails, L2TP control channels become available on standby RP 3. PPPoX session carried in the L2TP tunnels and IP addresses maintained as they were
before on the primary RP
Works with NSF (OSPF, IS-IS, BGP)Supports In-Service Software Upgrades (ISSU)Up to 16,000 L2TP sessions supported
Policy Control and Enforcement:ISG-SCE Common Control Bus
Service Control Engine (SCE) operates as delegate of the Intelligent Services Gateway (ISG) through a common control-bus:
ISG establishes subscriber-contexts on SCE and enforces policiesSCE provides ISG with application-layer accounting; ISG combines into master accounting records and communicates to OSS
Multimedia Services challenge existing broadband aggregation architecturesBroadband architectures can be distinguished along different dimensions
Geographical distribution (centralized vs. distributed)Single-edge vs. multi-edge policy enforcementClustered vs. unclustered
Centralized multi-edge broadband aggregation architecture can be evolved to facilitate the introduction of multimedia servicesClustering or multi-edge approaches improve overall service availability
K. Lee, F. Lim, B. Ong, “Building Resilient IP Networks”, Cisco Press, Dec. 2005, ISBN-13: 978-1-58705-215-6
T. Szigeti, C. Hattingh, “End-to-End QoS Network Design: Quality of Service in LANs, WANs, and VPNs:, Cisco Press, Nov. 2004, ISBN-13: 978-1-58705-176-0
B. J. Carroll, “Cisco Access Control Security: AAA Administration Services”, Cisco Press, May 2004, ISBN-13: 978-1-58705-124-1.
I. Pepelnjak, J. Guichard, J. Apcar, “MPLS and VPN Architectures, Volume II”, Cisco Press, Jun. 2006, ISBN-13: 978-1-58705-112-8.
I. Pepelnjak, J. Guichard, “MPLS and VPN Architectures”, Cisco Press, Oct. 2000, ISBN-13: 978-1-58705-002-2.
BRKNMS-2051 Optimizing a Service Provider Infrastructure for IPTV Services
BRKOPT-2111 Carrier Ethernet Aggregation Networks for Business and Residential Services
BRKVVT-2101 IPTV Service Architecture Design and Deployment
HeavyReading, “IP Video and the New Broadband Edge”, Vol. 3, No. 20, Dec. 2005.
HeavyReading, “Internet TV, Over-the-Top Video, & the Future of IPTV Services”, Vol. 5, No. 10, June 2007.
M. Iliofotou, P. Pappu et al., “Network Traffic Analysis using Traffic DispersonGraphs (TDGs): Techniques and Hardware Implementation”, available from http://www.cs.ucr.edu/~marios/Papers/UCR-CS-2007-05001.pdf
Ellacoya Networks, “Ellacoya Data Shows Web Traffic Overtakes Peer-to-Peer (P2P) as Largest Percentage of Bandwidth on the Network “, http://www.ellacoya.com/news/pdf/2007/NXTcommEllacoyaMediaAlert.pdf
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