TIM Group Politecnico di Torino. Torino, 18th January TIM Network. Alessandro Capello IP, Transport and Core Innovation

Transcription

1 TIM Group Politecnico di Torino Torino, 18th January 2018 TIM Network Alessandro Capello IP, Transport and Core Innovation

2 TIM Group 2

3 Agenda The PSTN Network The Data Network Current technological trends 3

4 Agenda The PSTN Network The Data Network Current technological trends 4

5 Public Switched Telephone Network: architecture Class 4 (SGT) Transmission network Class 5 (SGU) Branch Office (SL) Branch Office (SL) Distribution network Distribution network Distribution network Designedto carrya single typeof service: POTS (Plain Old Telephone Service) Transmission of analogue voice over the frequency band Hz Hierarchical structure Class 4 (SGT) Infrastructure Onion Cabinet Branch Office (SL) Distribution network Circuit switching technology Very well-known mathematical models to control the quality offered to customers (blocking probability): e.g. Erlang B Small/very small SL SL SGU SGT ~30 ~500 ~ 2000 ~ ~

6 Public Switched Telephone Network: equipment Distribution Frame Telephone Switch Transport Equipment 6

7 Agenda The PSTN Network The Data Network Current technological trends 7

8 From PSTN to Data Network Other operators Internet With the growth of the Internet, data services based on packet switching technologies become predominant Backbone network Data network carriesbothfixedand mobile Po P Po P Po P traffic for a variety of customers and services Services: web browsing, voice, video streaming, business applications, etc. Aggregation and access network Aggregation and access network Aggregation and access network Customers: residential, small business, large corporates, wholesale(other operators) Residential services Mobile services Business services 8

9 Data network: design Traffic matrix has completely changed in the last 15 years: increase in volume, decrease in locality Voice traffic Internationa l Data traffic Internet Backbone Backbone Area A Area B Area A Area B Topology and available infrastructures: buildings, conduits, cabinets, Typical goals of a network architecture design are: maximize utilization and availability, minimize cost and congestion Capacity planning and QoS are complementary tools: overprovisioning of resources vs. QoS management 9

10 Data network: properties DSLAM OLT Distribution network Point of Presence(PoP) Backbone Router BRAS PE Transmission network Aggregation Router Distribution network Distribution network AAA L3 services VPN Backbone Router Distribution network Backbone Aggregation Access 10

11 The Access network - Distribution Frame Street Cabinet Distribution Unit Primary Access Network Secondary Access Network m m 11

12 FTTx solutions Central office Cabinet Distribution Unit Building Tecnology Bit rate DS Copper xdsl m ADSL Mbit/s FTTCab OLT ONU xdsl m VDSL2 12 and 17 MHz profiles Mbit/s FTTB OLT ONU xdsl m VDSL2 30 MHz profile Mbit/s FTTH OLT GPON >100 Mbit/s 12

13 Ultra-broadband access technologies FTTH solution GPON with 1:64 splitting factor pt-to-pt for business FTTCab solution Extension of existing cabinet or new cabinet VDSL2 ports from the cabinet Small ONU with remote powering Large ONU with local powering 13

14 Bottlenecks are in the access Even if the total capacity in the access is much greater than in the backbone, the access is the real bottleneck Limitation UP/DW due to the capacity of the subscriber loop Capacity of the links between the aggregation network and the DSLAMs Cascading of DSLAM Statistical multiplexing does not help so much Upgrading the capacity is complex and takes time Simple tools to discard packets in congestion conditions 14

15 The Aggregation network Service PoP ~ 30 metro WDM WDM WDM FO/ SDH/ WDM FO OLT FO/SDH/ WDM FO/SDH/ WDM feeder ~500 ~ VDSL2 DSLAM IP 15

16 Optical Packet Metro OPM project was launched in 2005, concurrently with the introduction of Ethernet DSLAMs The network covers today more or less all the SGU sites (~ 500) SL sites connect to OPM through the transport network (PTN), the regional WDM network or dark fiber OPM is a multiservice network Fixed broadband aggregation IPTV Mobile backhauling Ethernet end-to-end services ATM transport Initially based on Ethernet technology moved to MPLS to increase scalability and decrease the convergence time on failure 16

17 The Point Of Presence PE Aggregation Network BNAS SH CDN Backbone Mobile Core DPI NAM PoP 17

18 BNG Broadband Network Gateway Residential and SOHO customers Retail: Internet Access, Internet Access + VoIP Wholesale K customers per node Point-to-Point VLAN to Access Nodes (PPPoE for customer separation) RADIUS protocol for communication with AAA servers Per session Authentication based on loop ID (and Username and Password) Dynamic configuration of a Virtual Interface per customer based on service profile (including Access Control List, Rate limiting, QOS, VPN, IPv6, ) Address assignment Per session Accounting Legal documentation requirements Collection of statistics High CPU usage due to authentication and accounting 18

19 PE Provider Edge router Business and TOP customers Internet Access, L2/L3 VPN, VoIP 2-10k customers per node Strong SLA (i.e. maintenance operations only during the night) Point-to-Point VLAN to Access Nodes (Q-in-Q for customer separation) MPLS on interface backbone side solution for providing both Internet Access and L2/L3 VPNs (and for adding IPv6) BGP protocol used to monitor the status of the link between the PE and the CE In case of failure backup connections are activated in less than 30s New solution based on Bidirectional Forwarding Detection (BFD): less CPU intensive, more reactive High CPU usage due to routing protocols 19

20 The Backbone network AS IS (OPB) TO BE (NGCN) 20

21 The underlying optical transport network Network diameter: km (workingprotection) Maximum number of hops: ROADM 60 DWDM ULH systemswith 80 lambdas 10 and 40 Gbit/s Optical Channel (OCh) 100 Gbit/s ready 21

22 The structure of NGCN T T T T Supercore T Primary PoP T T CS CS T Secondary PoP T T T CS CS T T T T T 8 Supercore(Primary) PoPs 25 Secondary PoPs 22

23 The routing plane Logical links IP Layer Control Plane Optical Layer Control Plane NMS Physical links IP Layer Provides packet based aggregation with QoS for traffic of different services IP routing and MPLS traffic engineering Topology based on traffic matrix (logical links) Optical Layer Provides multiplexing of different high speed signals to optimize the use of long distance optical fibers WDM multiplexing and optical switching Topology based on cable layout, strongly dependent on the geography of the Country (physical links) 23

24 Capacity planning OPB and OPM network design remove single point of failure All internal links are dimensioned following the 50% rule: each link can t be loaded by more than 50% of its capacity at the peak hour Warning thresholds are defined to allow planning for upgrades Continuous monitoring of the link load In a common operational situation, all traffic can cross the network with a minimum delay and with the maximum quality available. Inner Core PoPS Metro nodes 50% 50% 50% 50% Peripheral PoP Feeder Node 24

25 QoS Management Differentiated Service Model can be useful to protect critical traffic in case of multiple simultaneous faults Classification based on IP precedence, MPLS EXP or Ethernet CoS 3, 4 queues: a strict priority (typically for voice) queue and 2, 3 WFQ for different data classes Critical point is traffic marking: You cannot trust IP precedence of Internet IP packet most of the traffic in the backbone is in the Default class 25

26 QoS for business services (1/2) For a business access 3 parameters are defined: A peak bandwidth A Minimum Guaranteed Bandwidth (BMG): the minimum bandwidth that will be available also in congestion conditions The Real Time Bandwidth (RTB): the maximum traffic that is allowed in the Low Latency Queue For each access the PE applies a limitation of the peak bandwidth at the maximum value defined by the selected offer (e.g. 2 Mbit/s) Peak bandwidth is usually equal to the bandwidth available on the local loop However it may happen that the local loop bandwidth is lower than the peak bandwidth: differentiated queuing at the DSLAM level is still required to avoid discarding of critical traffic For each access the PE marks packets according to the BMG 26

27 QoS for business services (2/2) 3 queues for each access LLQ+2WFQ (Mission Critical and Default) Example of weights is 30:70 Hierarchical queuing multiple access on a single interface In case of congestion the bandwidth is distributed through the different accesses proportionally to the BMG parameter Access #1 WFQ LLQ C-VLAN Access #N LLQ WFQ PHY GE 27

28 QoS for residential services For a residential PPP a peak bandwidth is defined For a SOHO PPP session also a BMG is defined The BRAS applies a limitation of the peak bandwidth at the maximum value defined by the selected offer (e.g. Alice 7 Mega, Superinternet, ) If BMG is defined, the BRAS marks packets accordingly For each customer we have 1 or 2 queues (LLQ and default) Hierarchical queuing In case of congestion the bandwidth is distributed through the different sessions proportionally to the Peak bandwidth and the BMG parameters 28

29 Agenda The PSTN Network The Data Network Current technological trends 29

30 Software Defined Networking Traditional network Feature OS F Custom Hardware F Well-defined open APIs Network Service Application... Controller... Abstract Network View Network OS Application Network Service Open interface to applications (NorthBound API) Feature F F OS Custom Hardware Feature OS F F Custom Hardware Open interface to packet forwarding (SouthBound API) Hardware Hardware Separation between Data Plane and Control Plane The Control Plane is logically centralized Open APIs towards applications OpenFlow is one of the available options for the southbound interface Hardware 30

31 Disaggregation of networking functions Disaggregationreplicatesin networking technology what happened in IT technology with the migrationfrom proprietarymainframe systems to microprocessor systems with third party operating systems Images from Nick McKeown, Stanford University 31

32 Network Function Virtualization CPU and chipset are optimized to handle new types of workloads efficiently Functionalities that in past were feasible only with specialized hardware (e.g. ASIC) can be realized using general purpose CPU Virtual Network Functions (VNF) Network functions implemented as a coherent set of Virtual Resources Virtualization a bunchof sophisticated technologies capable of creating Virtual Resources out of the Infrastructure Infrastructure organized platform of computing, network, storage HW equipment 32

33 ETSI NFV Architecture (Specified in ETSI GS NFV-MAN 001) NFV Management & Orchestration OSS/BSS Os-Ma-nfvo NFV Orchestrator (NFVO) Network Service Management Manage combinations of connected VNFs NS Catalog VNF Catalog NFV Instances NFVI Resources EM Ve-Vnfm-em VNF Manager (VNFM) Or-Vnfm VNF Management Manage individual VNFs VNF Ve-Vnfm-vnf Vi-Vnfm Vn-Nf NFVI Nf-Vi Virtualised Infrastructure Manager (VIM) Or-Vi NFV-MANO Virtual Resource Management Manage the use of NFVI resources 33

34 Typical infrastructure of an NFV infrastructure site 34

35 Motivations for SDN and NFV SDN Lower riskof vendorlock-in; the availabilityof manysupplierscan reduce costs Easier automation of operational processes thanks to open APIs Global optimizations (by means of centralized control) NFV HW resources can be dinamically allocatedon the basisof realneeds: better efficiency and scalability HW resourcescan be easily(i.e. automatically) re-assigned to different network applications: faster deployment of new network applications Cost reduction(both CapEx and OpEx) Faster Time to Market 35

36 Open issues Technological aspects Organizational aspects Lack of cloud-native virtualized network applications Performance using shared, general purpose HW resources are less predictable Functions that use a lot of bandwidth (User Plane) require ad-hoc engineered solutions Automation of operational processes has huge impact on Service Providers internal organization New skills are required 36

37 Uniformity and standardization The benefits of SDN and NFV are amplified by applying uniformity and standardization to the infrastructure: lots of cheap and identical devices instead of few expensive and vendor-tailored devices (economies of scale) Central offices will progressively look like small data centers 37

38 Central Office Re-architected as a Datacenter 38

39 Grazie 39