Carrier-Grade Ethernet Technology

1. Reading material: “Ethernet as a Carrier Grade Technology: Developments and Innovations” by R. Sanchez, L. Raptis, K. Vaxenavakis Carrier-Grade Ethernet Technology Raimena Veisllari TTM1 lecture 13.09.2012

2. Outline • A short history of Ethernet • Reasons and Challenges for the Carrier Ethernet development • Carrier Ethernet characteristics • Scalability through VLAN hierarchy • Traffic Engineering (TE) • Operation, Administration and Management (OAM) • Deployment case study

3. The native Ethernet • 1973 - Metcalfe and Boggs (Xerox) • Shared medium access protocol • CSMA/CD, IEEE 802.3 (1980) • Coaxial Cable (”Ether”) based network • Thick Ethernet (10Base5) • Thin Ethernet (10Base2) • Twisted Pair (full-duplex communication, Base-T), Fiber (Base-X) • Repeaters and Hubs – one collision domain • Bridges and Switches – one broadcast domain

4. The native Ethernet • 7 octets Preamble for synchronization • Indication of SFD (10101011) start of MAC frames • 48 bit destination and source addresses • EtherType (upper layer protocol, e.g. IP)

5. Main characteristics • CSMA/CD (Do we still need it in switched Ethernet?) • Simplicity (plug n’play) and cost effective • The switching logic (self-configuration) • Listen, Learn and Forward • Redundancy through xSTP • VLAN known as a broadcast domain • Connection-less (single hop)

6. Why did Ethernet “win” in the customer domain? • There are LOTS of LAN protocols • Price! • Performance • Availability • Ease of use • Scalability • ….

7. Why Carrier Ethernet ? • SP infrastrucure based on legacy circuit-switched SDH/SONET, ATM, frame relay etc. • Ethernet as the technology of choice in the customer domain (85% of all networks and 95% of all LANs) • Internet is packet-switched • Eliminate potential internetworking problems • High bandwidth with simplicity and low cost

8. Carrier Ethernet Definition The MEF1) has defined Carrier Ethernet as “an ubiquitous, standardized, carrier-class Service and Network defined by five attributes that distinguish Carrier Ethernet from familiar LAN based Ethernet” • Standardized services • Scalability • Reliability • QoS • Service Management 1) http://metroethernetforum.org/index.php

9. Carrier Ethernet Challenges Moving Ethernet from the LAN to the carrier network brings out requirements/challenges: • Scalability • Support for 10exp6 customers of an SP • Evolving the VLAN-tagging standards • Protection (Reliability and Resiliency) • Achieve the required 50ms recovery time • Problems with xSTP recovery time • Other protocols required

10. Carrier Ethernet Challenges 3. Quality of Service • Hard QoS comparable with the guaranteed service from existing leased lines • Service Management • Service provisioning based on SLAs • Service Monitoring • Troubleshooting • TDM support • Inter-working with existing technologies (leverage the customer-driven investment)

11. Standardization Milestones

12. Scalability: Virtual LANs • IEEE 802.1Q Virtual LAN: • Management, security and scalability reasons. Layer3 between VLANs • 4094 available VLANs not enough for an SP! • Transparency problem within the SP backbone network! • A failure in the customer’s domain still affects the spanning-tree • of the provider’s core (transport) network

13. Q-in-Q Virtual LAN • IEEE 802.1ad Provider Bridges • Add a new S-VID to the frame (VLAN stacking) • Use the same MAC addresses through all the networks • A maximum of 4094 VLANs is a limitation for the provider!

14. MAC-in-MAC Virtual LAN • IEEE 802.1ah Provider Backbone Bridges (PBB) • Add a backbone MAC header (encapsulate the customers frame)

15. VLAN hierarchy evolution - MAC-in-MAC header encapsulation - 24 bit I-SID - Dedicated set of MAC addresses

16. IEEE 802.1ah (PBB) Provider Backbone Bridges provides: 1. 24 bit I-SID identifying the service in the SP => 16exp6 services 2. Total separation of the customer and SP networks • The MAC header is added at the edge of the SP • The backbone B-VID used for traffic engineering, ”zone”separation • SP control frames are independent from the customer’s ones 3. Tunneling Ref: «IEEE 802.1ah Update” Paul Bottorff, Editor 802.1ah

17. IEEE 802.1ah (PBB) Ref: «IEEE 802.1ah Update” Paul Bottorff, Editor 802.1ah

18. IEEE 802.1ah (PBB) • An I-SID uniquely identifies an S-VLAN with the Backbone • The I-SID to/from S-VID mapping is provisioned when a new service instance is created • B-VID : Separate the providers ID space : Many S-VLANs carried in a single B-VLAN Ref: «IEEE 802.1ah Update” Paul Bottorff, Editor 802.1ah

19. Ethernet Services • MEF defines the services as Ethernet Virtual Connections (EVC): • Point-to-point E-LINE • Point-to-Multipoint E-Tree • Multipoint-to-Multipoint E-LAN 1.1 Ethernet Private Leased Lines (EPL) • dedicated bandwidth 1.2 Ethernet Virtual Leased Lines (EVPL) • shared bandwidth

20. PBB-Traffic Engineering PBB-TE 802.1Qay introduced connection-oriented forwarding mode and Ethernet tunnels: • Forwarding is not based on the MAC learning mechanism but provided by the OAM plane • Turning off xSTP • Deterministic service delivery, QoS • Resiliency • OAM requirements

21. Carrier network with PBT

22. Operation, Administration and Maintenance (OAM) • Important building block toward carrier services Ethernet, multiple working/standardization bodies. • IEEE 802.1ag and ITU-T Y.1731: • Fault detection : Continuity Check Messages • Fault verification : Loopback and reply messages • Fault Isolation : Linktrace and Reply messages • ITU-T Y.1731 • Fault notification through Alarm Indication Signal • Performance monitoring • Frame Loss Ratio • Frame Delay • Frame Delay Variation

23. OAM example

24. Carrier Ethernet: What we looked into? Traffic Engineering OAM VLAN standards 1) http://metroethernetforum.org/index.php

25. Conclusions • Its simplicity and cost-effectiveness makes Ethernet a desirable technology for the NGN carrier networks • Can Ethernet still be considered ”simple” after the discussed changes??? • Native Ethernet is lacking capabilities for MAN and WAN environment. • PBB, PBB-TE and OAM aim to enhance Ethernet and provide the required carrier-grade services as from SONET/SDH, ATM and MPLS. • The competing carrier technologies OTN and IP/MPLS will be discussed in the course as well! • Resiliency? • Work in progress!

26. For further leisure reading • Examples taken from “The road to Carrier-grade Ethernet” K. Fouli, M. Maier http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4804387 • Metro Ethernet Forum MEF http://metroethernetforum.org/index.php

27. IP over Optical (1) Basic requirements: • High capacity optical layer network • Support high utilization of resources • Support high granularity • Support quality needed for strict real-time services • Support variable length packets

28. IP over Optical (2) • Legacy technology, e.g. SDH/SONET network infrastructures have provided a guaranteed level of performance and reliability for voice calls and leased lines. • Existing networks have been designed for telephony : static traffic patterns • Inefficient in handling the new traffic patterns that are dominated by data services. Increased traffic demands (e.g. from broadband home users/businesses and new services) => Fat pipes needed.

29. IP over Optical (3) ”IP everywhere” and development in optical technology => Focus on simplifications: What does the network look like?

30. IP over Optical (4)

31. IP over Optical (5) • Traffic bypassing intermediate IP routers == Less load on routers • smaller and cheaper • In meshed networks:Used to directly connect node pairs with high traffic load between them. Ref [1]

32. Optical cross-connect example • Wavelength switching done all-optically e.g. (transit traffic) • Locally destined wavelengths dropped/added (processed electronically)