Ethernet and its evolution towards Carrier Grade Ethernet

1. Ethernet and its evolution towards Carrier Grade Ethernet Marina Settembre

2. Agenda Ethernet and IEEE 802.3 Introduction on Ethernet origin and IEEE.802 project Frame format Medium Access Control Layer (CSMA/CD protocol, full duplex) Physical Layer (10 BASE-X, Fast Ethernet, Gigabit Ethernet) Switched Ethernet Bridges/switches Bridging process Spanning tree protocol Virtual LAN Basic VLAN concepts IEEE 802.1Q Carrier Grade Ethernet and Ethernet services Ethernet in MAN Ethernet services ( E-Line, E-LAN) Provider Backbone Transport

3. Why Ethernet? 98% of all data traffic start and end on an Ethernet port Easy to understand Low cost Strong industry support Continuous development Extensive topological flexibility Most dominant standard in the networking industry IEEE802.3 /ISO 8802.3 30 years of history Developed in 70s 1989 Standardized �90s : Switched Ethernet 1997: Fast Ethernet 1999: Gigabit Ethernet 2001 Metro Ethernet Forum 2002: 10 Gigabit Ethernet From LAN to MAN

4. Ethernet origin Invented by Metcalfe at Xerox in 1973 and patented in 1976 Xerox convinced Intel and Digital in joining and making products (hence the group called DIX) IEEE standard in 1989

5. Original Ethernet Ethernet was designed as a LAN technology: A Lan connects different computers together in a relatively small area through a single high transmission rate and low error rate(< 10-6, 10-7) physical channel In a LAN all computers/users share LAN resources with the same priority Transmission is broadcast: Need of medium access control (MAC is specific of each LAN solution) Bus topology Carrier Sense Multiple Access/Collision Avoidence (CSMA/CD) protocol is required (CSMA/CD) to avoid collisions Limitation to the physical dimension of the network and the bit rate.

6. MAC Half Duplex: CSMA/CD CS: Carrier sense (Is someone already talking?) MA: Multiple Access (I hear what you hear!) CD: Collision Detection ( Hey, we are both talking!) CSMA/CD rules: If the medium is idle, transmit anytime If the medium is busy, wait and transmit later If a collision occurs, send 4 bytes Jam, backoff for a random period, then go back to 1

7. MAC: collision domain Half-duplex Ethernet network must be configured to allow a station to detect a collision within a specified interval time Minimum packet size imposes a maximum network length

8. Full Duplex Transmission (for FE and GbE) Remember CSMA/CD and related physical limitations? Now forget it! Full duplex operation is an optional MAC capability that allows simultaneous bidirectional transmission over point-to-point links: transmitting while receiving! It is functionally simpler than half duplex since it involves: No media contention No collisions No need to schedule retransmissions Distance limitations are not due to MAC but on the physical media It must respect a minimum InterFrame Gap (IFG)

9. IEEE 802.3 IEEE802.3 is considered as the evolution of Ethernet and they are often considered as synonyms Covers Ethernet family of LAN products Supports two transmission modality: Half Duplex (CSMA/CD protocol) Full duplex (only for FE,GbE and 10 GbE) Defines four data rates for operation over optical fiber and/or twisted-pair cables: 10 Mbps 100 Mbps � Fast Ethernet 1000 Mbps � Gigabit Ethernet 10 Gbps � 10-Gigabit Ethernet

10. Ethernet Frame Frame size varies from 64 to 1518 Bytes, except when VLAN tag is supported (more on that later..)

11. The Ethernet Physical Layer The naming convention is a concatenation of three terms indicating the transmsission rate, the transmission method, and the media type/signal encoding (Es: 10 Base-T)

13. Switches Switches allow to create larger Ethernet systems by linking multiple collision domains together

14. Bridges/switches Switches operate at the Data Link Layer (Layer 2) IEEE 802.1D bridge operates in store and forward mode (complete reception of the frame before transmission)

15. Hubs vs Switches

16. Main processes in a bridge (IEEE 802.1D Transparent Bridge) The bridging process deals with: Frames forwarding from input to output port Build and update the database for forwarding decisions The spanning tree process this process is essential in presence of loops

17. Forwarding and filtering data base Each bridge maintains a forwarding database/routing table (filtering data base) with the following entries: < MAC address, port, age> MAC address: host address port: port number of bridge age: aging time of entry

18. Frame forwarding

19. Address Learning Creating a new entry in the database with source MAC address, if not existing Flooding on all the ports but the source one Database updating

20. Danger of Loops Consider the two LANs that are connected by two bridges Assume host n is transmitting a frame F with unknown destination

21. Spanning Tree A solution is to prevent loops in the topology IEEE 802.1d has an algorithm that organizes the bridges as spanning tree in a dynamic environment Bridges exchange messages to configure the bridges (Configuration Bridge Protocol Data Units (BPDUs)) to build the tree

22. Routers Routers operate at the Network Layer (Layer 3) Interconnect IP networks

23. Interconnected devices

25. What are VLANs ? A Virtual LAN is a method of creating independent logical networks within a single physical network infrastrucure or in other words� A Virtual LAN is a logical segmentation of a broadcast domain (switched network) into different broadcast domains

26. Why VLANs? Advantages: Reduces the broadcast traffic and increases network security (both of which are hampered in case of single large broadcast domain) Reduces management effort to create subnetworks Reduces hardware requirement, as networks can be logically instead of physically separated Increases control over multiple traffic types

27. Why are VLANs needed? An example

28. A possible solution: Routers

29. Another solution: move users or cables

30. Easier solution: VLANs

31. VLAN Intra-Switch Switch Ports are grouped into different broadcast domains

32. VLAN Inter-Switch Sharing VLAN among switches is achieved by inserting a tag with a VLAN identifier in each frame (802.1Q VLAN standard specification)

33. VLAN Tagging Scheme: IEEE 802.1Q Tag Protocol Identifier (TPID): identifies the frame as a tagged frame Tag Control Information (TCI) with the following fields: User priority: carries priority information based on the values defined in the 802.1p standard Canonical Format Indicator (CFI): allows Source Routing control Information to be specified VLAN identifier (VID): uniquely identifies the VLAN to which the frame belongs

34. 802.1p Standard The 802.1p standard defines a scheme to prioritize different types of traffic in Ethernet The forwarding process may provide more transmission queues for each switch port Frames will be assigned to each queue according to their user_priority

35. Trunk links A trunk link attaches two VLAN switches It carries tagged frames only

36. Trunk links

37. Access Links Accees links are untagged for VLAN unaware devices The VLAN switch adds tags to received frames and removes taggs when transmitting frames

38. Agenda Ethernet and IEEE 802.3 Introduction on Ethernet origin and IEEE.802 project Frame format Medium Access Control Layer (CSMA/CD protocol, full duplex) Physical Layer (10 BASE-X, Fast Ethernet, Gigabit Ethernet) Switched Ethernet Bridges/switches Bridging process Spanning tree protocol Virtual LAN Basic VLAN concepts IEEE 802.1Q Carrier Grade Ethernet and Ethernet services Ethernet in MAN Ethernet services ( E-Line, E-LAN) Provider Backbone Transport (PBT)

39. In the beginning ..

40. Increasing proportion of packet traffic

41. Services driving demand for packet based technology Three main areas of broadband explosion are driving Carrier Ethernet: Business Services � where Gigabit connectivity becomes a must with requirement of data center consolidation, storage and disaster recovery, gigabit connectivity between businesses, and through supply chain. Residential Services � where Triply Play/IPTV becomes broadband driver to deliver >20 Mb to homes with TV, VoD, telephony and Internet services Mobile Services � where wireless 3G packet traffic , in addition to WiMAX and Wi-Fi backhaul, will surpass voice traffic just like in the wireline world. All of these broadband requirement drives a new packet friendly infrastructure, where Carrier Ethernet thrives.Three main areas of broadband explosion are driving Carrier Ethernet: Business Services � where Gigabit connectivity becomes a must with requirement of data center consolidation, storage and disaster recovery, gigabit connectivity between businesses, and through supply chain. Residential Services � where Triply Play/IPTV becomes broadband driver to deliver >20 Mb to homes with TV, VoD, telephony and Internet services Mobile Services � where wireless 3G packet traffic , in addition to WiMAX and Wi-Fi backhaul, will surpass voice traffic just like in the wireline world. All of these broadband requirement drives a new packet friendly infrastructure, where Carrier Ethernet thrives.

42. Ethernet drivers in the Metro Area Ease of use Widely available, well understood technology Simplifies network operations (OAM&P) Packet based technology IP compatible Flexibility Single interface can connect to multiple services Internet, VPN, Extranet supplier, Storage Provider Bandwidth can be added in 1Mbps increments Cost Effectiveness Widespread use of Ethernet interface Purchase bandwidth only when needed

43. Ethernet from a carrier perspective Ethernet as a service: Metro Ethernet Network Packet based telecom services that offer an Ethernet interface to the customer and ensure reliable delivery of Ethernet packet data. Ethernet as a transport technology in Metro Area: Carrier Grade Ethernet It is not a prerequisite for delivery Ethernet services and up to now has lacked the features that carriers require, but latest evolutionary steps in layer 2 networks seem to be very promising from a carrier perspective

44. Ethernet as a service Ethernet services are packet based services that offer an Ethernet interface ( or UNI) to the customer (CE) and ensure reliable delivery of Ethernet packet data Ethernet services do not have necessarily to be delivered using Ethernet tranport The services are defined only in terms that are observable to the CE

45. Ethernet service model defined by MEF CE can be router IEEE 802.1Q bridge (switch) UNI (User Network Interface) Standard IEEE 802.3 Ethernet PHY and MAC 10Mbps, 100Mbps, 1Gbps or 10Gbps Metro Ethernet Network (MEN) May use different transport and service delivery technologies SONET/SDH, WDM, RPR, MAC-in-MAC, Q-in-Q, MPLS Service frame With IEEE 802.1Q tag (up to 1522 bytes) Without IEEE 802.1Q tag (up to 1518 bytes)

46. Ethernet Virtual Connection(EVC) An EVC is �an instance of an association of 2 or more UNIs� EVCs help conceptualize the service connectivity Like Frame Relay and ATM PVCs MEF has defined 2 EVC types Point-to-Point (It associates only 2UNIs) Multipoint-to-Multipoint (It associates 2 or more UNIs)

47. E-Line Services Provided by means of point-to-point EVC E-Line Services can be used to create Ethernet Private Line Services Ethernet Internet Access Ethernet Point-to-Point VPNs( EVPL) (service multiplexing can be supported at UNI to minimize power, space and cost)

48. E-LAN Services Provided by means of multipoint-to-multipoint EVC E-LAN Services can be used to create Multipoint VPNs Transparent LAN Service

49. E-Tree Services (1/2) Provided by point-to-multipoint EVC Ethernet Private Tree (EP-Tree), Ethernet Virtual Private LAN (EVP-LAN) Used for Triple Play services

50. E-Tree Services (2/2) At least one UNI should act as a �Root� The other UNIs are �Leaf� A frame can be sent from a Root to one or more Leaves A frame cannot be sent from a Leaf to a Leaf

51. Carrier Grade Ethernet Requirements

52. Technologies for Carrier Ethernet Services MEF defines service models, put requirements, but does not define the transport technologies Legacy transport technologies: WDM : it uses wavelenghts Bandwidth wasting for low bit rate EVC SDH: it uses Virtual Circuits and GFP Expensive �and circuit technology ATM: ATM LAN Emulation service (ATM LANE) Packet technology..but expensive IP/MPLS: Virtual Private LAN Service (VPLS) Packet technology ..but still expensive for metro area Emerging transport technologies: Ethernet-based technology: Provider Bridge (PB), Provider Backbone Bridge (PBB), and Provider Backbone Bridge � TE (PBT) MPLS-based technology:T-MPLS

53. Evolution of Ethernet towards Carrier Ethernet Two key issues to be addressed: Evolution from flat to hierachical approach IEEE 802.1Q ( Q-Tag) IEEE 802.1ad ( Q-in-Q) - Provider Bridge IEEE 802.1ah (MAC-in-MAC) - Provider Backbone Bridge Evolution from connectionless to deterministic connection oriented forwarding IEEE 802.1Qay - Provider Backbone Bridge �TE (or PBT)

54. Hierarchical tunneling in Ethernet: Q-tag First Hierarchical level: 802.1Q (Q-tag for VLAN support)

55. Hierarchical tunneling in Ethernet: Q-in-Q Second Hierarchical level: 802.1ad - Provider Bridges (PB) The original Q-tag (C-VID) is used to identify VLANs within the customer�s network The S-VID tag allows the service provider to administrate their own tags to identify individual customer networks and better manage its own traffic

56. Hierarchical tunneling in Ethernet:MAC-in-MAC Third Hierarchical level: 802.1ah - Provider Backbone Bridge (PBB) It encapsulates the customer MAC header with a service provider Mac header I-SID identify the Instance ID B-VID represent flood domains that interconnect multiple PB networks B-DA (B-SA) are the Backbone Destination (Source) addresses, which are totally indipendent of customer ones (those ones are transparently carried through the provider domain)

57. Evolution of Ethernet tunneling Without a hierarchy Ethernet networks have a flat structure Q-tag identifies VLAN Q-inQ identifies customer MAC-in-MAC allows to transparently transport customer frame from UNI to UNI

58. IEEE 802.1Qay - PBB-TE (PBT) Provider Backbone Bridge - Traffic Engineering (PBB-TE), also known as Provider Backbone Transport (PBT) has the following features: Introduces a connection oriented forwarding mode by turning off Mac learning and Spanning Tree Protocol Provides TE functionalities, hard QoS and resiliency Forwarding information is provided by an external agent (Management plane or Distributed Control plane) Does not change data plane behaviour of PBB Bridges (VID + D-MAC)

59. Ethernet evolution summary

60. GMPLS Controlled Ethernet Develop a native packet-oriented transport technology GMPLS to support CO-Ethernet provisioning and reconfiguration A common transport control plane can reduce errors due to manual database configuration A control plane can responds in real time

61. GMPLS Controlled Ethernet and ASON IETF CCAMP working group is extending the GMPLS control plane for PBB-TE Ethernet networks GMPLS controlled Ethernet label switching (GELS) Objective: Meet the requirements of ITU-T G.8080 framework architecture (ASON)

62. Forwarding technologies Routed (IP/MPLS) Bridged: 802.1ad (Q-in-Q) 802.1ah (MAC-in-MAC) Spanning tree variants Tunnelled: 802.1Qay PBB-TE T-MPLS