Torino, January 12th 2021 GRUPPO TIM The evolution of TIM's network architecture and management Alessandro Capello Technology Innovation Agenda #1 Network architecture #2 Capacity planning and QoS management #3 Network management #4 Evolution of network architecture and management ALL ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 2 Requirements Network architecture For all services: • Connectivity matrix • Throughput • Latency • Availability Goals Where? Satisfy the requirements at the minimum cost What? Physical Technologies topology Infrastructure Constraints The buildings hosting network equipment The ducts carrying the optical fiber cables How? Logical topology Technology Constraints ALL ALL RIGHTS RESERVED Multiple network layers Transmission limitations 2021, Interface speed © TIM Device fan-out and switching performance PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 3 The architecture of the (old) Telephone Network Branch Office Distribution (SL) network Class 4 (SGT) Branch Office Distribution (SL) network Designed to carry a single type of service: Transmission Class 5 Distribution network (SGU) network transmission of analog voice over the frequency band 300–3400 Hz Class 4 Branch Office Distribution Hierarchical structure (SL) network (SGT) Circuit switching technology Very well-known mathematical models to control the quality offered to customers Cabinet (blocking probability) Small/very small SL SL SGU SGT ~30 ALL RIGHTS RESERVED ~500 2021, ~ 2000 © TIM ~ 10000 ~ 150000 PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 4 The architecture of the Data Network DSLAM OLT Distribution network With the growth of the Internet, data services based on packet Point of Presence (PoP) switching technologies become predominant Backbone Router Data network carries both fixed and Distribution mobile traffic for a variety of network Aggregation customers and services Router BNG Services: web browsing, voice, video PE Distribution Transmission network network streaming, business applications, etc. AAA L3 services VPN Customers: residential, small business, large corporates, Distribution network Backbone wholesale (other operators) Router ALL RIGHTS RESERVED 2021, © TIM © TIM Backbone Aggregation Access PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 5 The backbone ALL ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 6 The optical network Network diameter: 2400-3100 km (working-protection) 52 ROADMs Optical links with 96 channels @ 100 Gbps and 200 Gbps ALL ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 7 The Points of Presence PE BNG Backbone Aggregation Network CDN Caching ALL ALL RIGHTS RESERVED Mobile Core 2021, © TIM © TIM PoP PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 8 BNG – Broadband Network Gateway • Residential and SOHO customers • Retail: Internet Access, Internet Access + VoIP • Wholesale • 20-100K 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) BNG • 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 ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 9 PE – Provider Edge router Business services • 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) E P 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 (BGP sessions toward customers) ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 10 Limitations of current architecture Network upgrades are expensive considering The introduction of new network services is the current traffic growth slow Many hops between source and destination Need to deploy physical devices Network functions are developed within Integration with legacy management systems specialized network equipment Legacy network devices are expensive and many features are not used in practice ALL ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 11 Agenda #1 Network architecture #2 Capacity planning and QoS management #3 Network management #4 Evolution of network architecture and management ALL ALL RIGHTS RESERVED MARKET SENSITIVE 2021, - © TIM © TIM CONFIDENTIAL PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 12 Capacity planning and QoS management Traffic matrix has completely changed in the last 20 years Voice traffic Data traffic International Internet Volume Backbone Backbone Locality Area A Area B Area A Area B Capacity planning and Capacity planning involves QoS management means Quality of Service upgrading the network differentiating traffic management are the infrastructure (interface behavior in case of ALL RIGHTS RESERVED main tools to manage speed, number of network congestion 2021, traffic evolution interfaces, ecc.) to carry © TIM more traffic PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 13 Capacity planning The network design avoids single points of failure All internal links are dimensioned following the 50% rule: each link can’t be loaded more than 50% of its capacity @ peak hour Continuous monitoring of the link load 50% rule 50% Warning thresholds are defined to allow planning for upgrades Peak and average traffic rates are collected for all interfaces Traffic matrix is estimated using gravity models Algorithms for traffic prediction must consider both legacy and new services prediction ALL ALL RIGHTS RESERVED 2021, © TIM © TIM Traffic Traffic PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 14 QoS Management 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 DiffServ 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 ALL ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 15 QoS for business customers For a business access, 3 parameters are defined: • A peak bandwidth • A Minimum Guaranteed Bandwidth (MGB): 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 The network applies a limitation of the peak bandwidth at the maximum value defined by the selected offer Peak bandwidth is usually equal to the bandwidth available on the local loop Business customers Business It may happen that the local loop bandwidth is lower than the peak bandwidth: differentiated queuing at the access level is still required to avoid discarding of critical traffic The network marks customer packets according to the MGB ALL RIGHTS RESERVED 2021, © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 16 QoS for business customers Access #1 Access #N WFQ WFQ • 3 queues for each customer LLQ LLQ • LLQ + 2 queues with WFQ (Mission Critical and Default) • Example of weights is 30:70 • Hierarchical queuing configuration • multiple access on a single interface • In case of congestion the bandwidth is C-VLAN Queue distributed through the different accesses proportionally to the MGB parameter ALL ALL RIGHTS RESERVED 2021, PHY GE © TIM © TIM PUBLIC PUBLIC USE The evolution of TIM's network architecture and management Alessandro Capello, Technology Innovation 17 QoS for residential customers For a residential access only a peak bandwidth is defined The network applies a limitation of the peak bandwidth at the maximum value defined by the selected offer customers For each customer, 1 or 2 queues (LLQ and default) are configured