1. Nortel Confidential Information 1 Provider Backbone Transport Alan Beard Dir Business Development 19 th November 2007

2. Nortel Confidential Information 2 What’s in common between… Triple play - DSLAM Connectivity ATM DSLAMs DSLAM Data Business ServicesWireless Backhaul ? ? ? Triple Play - Fibre To The Home ?

3. Nortel Confidential Information 3 >Ethernet VPNs >Any-to-any L2 connectivity >Cost effective alternative to L3 VPNs >Simple to manage and operate >Scalable bandwidth >Improved security through L3 transparency 3 RD GENERATION >IP-VPNs >RFC2547 based >Connectionless >Hosted service >Layer 3 adds complexity 2 ND GENERATION VPN Evolution >Virtual Leased Line (VLL) >ATM/Frame Relay >Shared bandwidth >Cost effective alternative to leased lines >Multiple connections create complex mesh 1 ST GENERATION

4. Nortel Confidential Information 4 Network Layer Reduction (Metro) Layer 0 – Wavelength Layer 1/2 – Ethernet – PBB/PBT Layer 3 – IP Layer 0 – Wavelength Layer 1 – SDH Layer 2 – Ethernet Layer 3 - IP Layer 1.5 – GFP, LCAS, VCAT TODAY

5. Nortel Confidential Information 5 Ethernet Solutions Ethernet as a Service >Offered and sold as connectivity >Aimed at Business Market Services Ethernet VPNs Ethernet Private Line Ethernet Virtual Private Line Ethernet Virtual Private LAN Ethernet as an Infrastructure >Support of Residential and Business Services Triple Play: Voice/Video/Data Internet Access Storage >Metro Aggregation DSL Aggregation Wireless Backhaul Internet Access and IP VPNs Service Provider Voice ASP Data Video CE Point-to-Point EVC UNI E-Line Service type

6. Nortel Confidential Information 6 Enterprise-class Ethernet Switches Lack Critical Service Provider Pre-requisites Existing Ethernet Challenges: Overlapping addresses; Secure separation & demarcation of customers & provider Service Scalability OAM equivalent or better than current provider OSS systems Traffic Engineering & QoS Carrier-grade resiliency with bandwidth efficiency Lower Cost per Mbps Reduced CAPEX Reduced OPEX & Simplified OAM Higher Service Scalability & Flexibility Traffic Engineering Resource Reservation Dynamic Provisioning Differentiated Services Network Resiliency Ethernet as used today is lowest cost but has several issues:

7. Nortel Confidential Information 7 Nortel’s Carrier Ethernet Solution Guaranteed SLAs & determinism via PBT Carrier-class OAM Customer encapsulation (PBB/PWE) Keep Ethernet Simple & Cost Effective

8. Nortel Confidential Information 8 IEEE 802.1ah Encapsulation Provider Backbone Bridging Ethernet Header Payload 802.1Q Tag 1. Q tag identifies VLAN Ethernet Header Outer Tag 802.1Q Tag Payload 2. Service Provider Q tag identifies customer 802.1ah Header Ethernet Header 802.1Q Tag Payload 3. Customer frame is transparently tunneled from UNI to UNI

9. Nortel Confidential Information 9 IEEE 802.1ah (PBB) Encapsulation >Scalability 16 million VPNs >Security Clear demarcation between service provider and customer >Robust Spanning Tree Protocol convergence in the customer network doesn’t affect service provider network >Service management Service provider MAC provides an end to end service ID Provided simple efficient Any to Any service Characteristics

10. Nortel Confidential Information 10 Nortel’s Strategy >Ethernet switches are the telecommunications infrastructure with the lowest cost point >We can re-purpose these switches with new control software to meet carrier needs >This can be done with minimal changes to Ethernet standards and those changes are in progress >This can be done while preserving investment in service provisioning Keep Ethernet simple, flexible and cost effective

11. Nortel Confidential Information 11 Provider Backbone Transport (PBT) >A simple point-to-point Ethernet tunneling technology Reserve bandwidth Deliver hard QoS Offer 50 ms recovery Provides “SDH like” guaranteed performance & SLAs Carrier Ethernet Traffic Engineered PBT trunks Trunk manager

12. Nortel Confidential Information 12 How Does PBT Work? >Turn off Broadcast unknown MAC learning functionality Spanning Tree Protocol >Give control of the forwarding tables to the Provisioning system >Ethernet still switches based on forwarding table information Forwarding/Data Signaling/Control Management Reuses existing Ethernet hardware and cost points

13. Nortel Confidential Information 13 PBT Example >Normal forwarding using: destination MAC address + VLAN-ID (DA + VLAN-ID) >PBT reserves a subset of VLAN tags VLAN tag is no longer globally unique Service and Network Management SA: PE1 Trunk defined by DA: PE3 + VLAN 45 Customer Network MAC-in-MAC encapsulation Customer Network Trunk manager MAC-in-MAC encapsulation Combination of VLAN tag and MAC address is unique

14. Nortel Confidential Information 14 Service and Network Management Customer Network MAC-in-MAC encapsulation Customer Network Trunk manager PBT Example >Backup path can be configured for resiliency Paths can use the same Destination MAC >Both paths are monitored by CFM control frames active path forwards packets if CFM measures active path down, switchover to backup in 50ms SA: PE1 Trunk defined by DA: PE3 + VLAN 45 SA: PE1 Trunk defined by DA: PE3 + VLAN 44

15. Nortel Confidential Information 15 The End Result >Solves MAC learning problems MAC Explosions, Service Scalability >New forwarding mode results in Traffic engineering Resiliency Hard QoS >Comprehensive OAM Ethernet OAM is on track to surpass MPLS OAM Low risk play…..reuses existing Ethernet switches

16. Nortel Confidential Information 16 MPLS Services (RFC 2547 VPN, PWs etc.) Ethernet Services (EVPL, ELAN, ELINE, Multicast) >Keep existing Ethernet & MPLS services >Capitalize on Ethernet as transport for significant savings >Existing network-friendly solution! PBT Nortel Technology Innovation: Provider Backbone Transport

17. Nortel Confidential Information 17 Back Up

18. Nortel Confidential Information 18 MPLS Dissected: 2 separate layers 1.MPLS provides a Service Layer Revenue generating L3 VPNS (2547), L2 VPNs (PWs, VPLS) 2.MPLS also provides a Tunnel layer Provides networking functionality Adds significant cost to your equipment and operations teams Can we eliminate this layer of cost for metro transport? Yes! MPLS Tunnel Layer Customer Payload MPLS Service Layer L1 Header Ethernet Header

19. Nortel Confidential Information 19 The Virtues Of Tunneling PBT HEADER PW over PBT VF PWs VPLS over PBT VSI VPLS PBB over PBT I-SID PBB Ethernet Surpasses MPLS: MPLS Tunnel Layer Customer Payload Pseudowire Service Label L1 Header Ethernet Header VPLS PBB (802.1ah) Any Service! PBT works with any service layer

20. Nortel Confidential Information 20 Ethernet OAM >802.1ag gives: Rapid notification of end-to-end connectivity failure. Where is broken link? MTU/priority-related faults → Faults found & fixed quicker & more easily. >Y.1731 measures: Frame delay, delay variation, frame loss AIS → Diagnostics/monitoring to support premium high-QoS services >Resiliency and Protection switching (ITU G.8031) Provides 50ms protection switching >802.1ab Autodiscovery → fast and accurate network topology view “SDH Like” simple operational paradigm - Functionality is on the box, EMS/NMS not involved

21. Nortel Confidential Information 21 EMS - Metro Ethernet Manager (MEM) Integrated Carrier Ethernet / Optical / MSS management platform

22. Nortel Confidential Information 22 PBT Standards >PBT architecture uses existing standards >The remaining areas are being addressed by the IEEE and ITU-T IEEE approves work on PBT PAR (November 06) IEEE working group launched Jan07. G.pbt Provider Backbone Transport Architecture introduced in February 06

23. Nortel Confidential Information 23 Standards Body Standards ProjectApprovedDraftUnder Discussion 802.1AB Discovery 802.1ad Provider Bridges 802.1ag Connectivity Fault Management 802.1ah Provider Backbone Bridges Y.1731 Ethernet OAM Mechanisms G.8031 Ethernet Protection       Standards Summary PBT on target to be standardised in 2007

24. Nortel Confidential Information 24