Tema 2: Tecnologías LAN.

1. Tema 2: Tecnologías LAN. Evolución de Ethernet. Ethernet para MANs VPLS EtherChannel Resilient Ethernet: HSRP

2. Overview • Ethernet is the dominant LAN technology. • Easy to implement; flexible. • 10BASE5, 10BASE2, & 10BASE-T Ethernet • Manchester encoding • Ethernet timing limits • 10BASE-T wiring parameters • 100-Mbps Ethernet (Fast Ethernet) • Gigabit Ethernet • MAC, frame formats, & transmission process • media and encoding • pinouts and wiring • Gigabit and 10-Gigabit Ethernet

3. 10 Mbps Ethernet • 4 common features of Legacy Ethernet: • timing parameters, frame format, transmission processes, & basic design rule. • Asynchronous • Uses Preamble and SFD for synchronization • Slot Time • For speeds ≤1000 Mbps, minimum transmission time

4. 10BaseT • Introduced in 1990 • UTP cheaper & easier to install than co-ax. • Star or extended star topology. • Supports half- & full-duplex. • 10 Mbps at half-duplex; 20 Mbps at full-duplex. • Manchester encoding • Max unrepeated distance 100m • UTP Categories: • 3 - 16 Mhz, 100 ohms • 4 – 20 Mhz, 100 ohms • 5 – 100 Mhz , 100 ohms • 5e – 350 Mhz, 100 ohms

5. 10BaseT Wiring & Architecture • Star topology • Hub or switch as concentration point. • Switch divides into separate collision domains. • Design concern – minimize delay between distant stations.

6. 100 Mbps or Fast Ethernet • Two technologies: • 100Base-TX : copper UTP • 100Base-FX : multimode optical fiber • Same frame format as 10 Mbps Ethernet • 10x faster than 10Base-T • Timing is more critical; • more susceptible to noise. • Uses two encoding steps • 4B/5B • Actual line encoding.

7. 1000 Mbps or Gigabit Ethernet • Standards • IEEE 802.3ab – Gigabit using Cat 5, or higher. • IEEE 802.3z - Gigabit over optical fiber. • 1000Base-TX, 1000Base-SX, & 1000Base-LX use same timing, transmission, & frame format. • Uses two separate encoding steps: • At physical layer, bit patterns from the MAC layer are converted into symbols. • frame is coded into control & data symbols to increase in network throughput.

8. 1000Base-T • Designed for Cat 5e or better UTP. • uses all four pairs of wires; full-duplex transmissions on each wire pair! - 250 Mbps per pair; 1000 Mbps for 4 wire pairs. • Data is divided into 4 parallel streams, encoded, transmitted, detected, and reassembled. • Supports both half and full duplex. • Full-duplex is widespread. • 4D-PAM5 – Pulse Amplitude Modulation

9. 1000Base-SX and LX • IEEE 802.3 standard recommended preferred backbone technology • Timing, frame format, & transmission are common to all versions of 1000 Mbps. • Uses 8B/10B encoding; and NRZ line encoding.

10. 1000Base-SX and LX (2) • SX vs LX • SX is short-wavelength • 850 nm; multimode. • LX is long-wavelength • 1310 nm; single or multimode. • MAC method treats link as point-to-point. • Separate fibers for Tx and Rx. • Inherently full duplex. • Gigabit Ethernet permits only a single repeater between two stations.

11. Gigabit Ethernet Architecture • Distance limitations of full-duplex links • limited only by the medium; not round-trip delay. • Auto-Negotiation recommended for all links between station & hub or switch. • to permit highest common performance.

12. 10 Gigabit Ethernet • IEEE 802.3ae standard (2002). • 10 Gbps full-duplex transmission over fiber. • Use in LANs, MANs, WANs. • distance to 40 km over single-mode fiber. • compatibility with SONET and SDH networks. • Properties • Same Frame format • Compatible with legacy, fast, & gigabit, with no reframing or protocol conversions. • Bit time is 0.1 nanoseconds. • Full-duplex only (CSMA/CD not necessary). • IEEE 802.3 sublayers within OSI Layer 2 are preserved. • Some additions to accommodate 40 km fiber links and interoperability with SONET/SDH technologies. • Flexible, efficient, reliable, relatively low cost end-to-end Ethernet networks become possible.

13. 10 Gigabit Ethernet (3) • Implementations being considered: • 10GBASE-SR • for short distances (26 – 82 m) over multimode fiber. • 10GBASE-LX4 • distances 240 m to 300 m over multimode fiber, and 10 km over single-mode fiber. • 10GBASE-LR & 10GBASE-ER • 10 km & 40 km over single-mode fiber. • 10GBASE-SW, 10GBASE-LW, & 10GBASE-EW • to work with OC-192 synchronous transport module SONET/SDH WAN equipment.

14. 10 Gigabit Ethernet Architecture • Issues of synchronization, bandwidth, and Signal-to-Noise Ratio: • 10-Gigabit Ethernet uses two encoding steps. • uses codes (symbols) for user data give efficient transmission. • encoded data provides synchronization, efficient use of BW, and improved Signal-to-Noise Ratio. 

15. Future of Ethernet • Ethernet is evolving into LAN, MAN, & WAN technology. • Standards for 40, 100, or even 160 Gbps are being developed. • Full-duplex high-speed Ethernet technologies are taking over even QoS-intensive applications. • Like: IP telephony & video multicast.

16. Evolución de Ethernet Acceso Distribución Metro Metro Core Casa Residencial MDU ATM ADSL T1/E1 FR ATM ATM SONET/SDH ATM SONET/SDH Global Internet STU Empresa MTU Optical Ethernet EoMPLS VPLS EoRPR NG-SONET(EoS) Metro DWDM Optical Ethernet EoMPLS VPLS RPR NG-SONET(EoS) Metro DWDM IP ADSL IP VDSL EPON EFM Optical Ethernet EoRPR NG-SONET(EoS) Global Internet

17. Servicios Metropolitanos • Algunos servicios son: • Conectividad Internet • Transparent LAN service (punto a punto LAN to LAN) • L2VPN (punto a punto o multipunto a multipunto LAN to LAN) • Extranet • LAN a Frame Relay/ATM VPN • Conectividad a centro de backup • Storage area networks (SANs) • Metro transport (backhaul) • VoIP • Algunos se están ofreciendo desde hace años. La diferencia está en que ahora se ofrecen usando conectividad Ethernet !!

18. Servicio Ethernet – Modelo de referencia • Customer Equipment (CE) se conecta a través de UNI • CE puede ser un • router • Bridge IEEE 802.1Q (switch) • UNI (User Network Interface) • Standard IEEE 802.3 Ethernet PHY and MAC • 10Mbps, 100Mbps, 1Gbps or 10Gbps • Soporte de varias clases de servicio (QoS) • Metro Ethernet Network (MEN) • Puede usar distintas tecnologías de transporte y de provisión de servicio • SONET/SDH, WDM, PON, RPR, MAC-in-MAC, QiQ (VLAN stack), MPLS CE UNI Metro Ethernet Network (MEN) CE UNI CE

19. Servicio Ethernet – Modelo (2) • Sobre el anterior modelo, se añade un cuarto ingrediente: una Ethernet Virtual Connection (EVC) • EVC: es una asociación entre dos o más UNI • Es creada por el proveedor del servicio para un cliente • Unatramaenviada en un EVC puede ser enviada a uno o más UNIs del EVC: • Nuncaseráenviada de vuelta al UNI de entrada. • Nuncaseráenviada a un UNI que no pertenezca al EVC. • Las EVC´s pueden ser: • Punto a punto (E-Line) • Multipunto a multipunto (E-LAN) • Cada tipo de servicio ethernet tiene un conjunto de atributos de servicio y sus correspondientes parámetros que definen las capacidades del servicio.

20. Atributos de un servicio en particular Ethernet • Multiplexación de servicios • Asocia una UNI con varias EVC. Puede ser: • Hay varios clientes en una sóla puerta (ej. En un POP UNI) • Hay varias conexiones de servicios distintos para un solo cliente • Transparencia de VLAN • Significa que proveedor del servico no cambia el identificador de la VLAN ( el MEN aparece como un gran switch) • En el servicio de acceso a Internet tiene poco importancia • “Bundling” • Más de una VLAN de cliente está asociada al EVC en una UNI • Etc.

21. Atributos • Atributos de UNI: • identificador, tipo de medio, velocidad, duplex, etc • Atributo de soporte de VLAN tag • Atributo de multiplexación de servicio • Security filtersattribute • etc • Atributos de EVC: • Parámetros de tráfico (CIR, EIR, in, out, etc) • CommittedInformationRate (CIR) • ExcessInformationRate (EIR) • Parámetros de prestaciones (delay, jitter, etc) • Parámetros de Clase de Servicio (VLAN-ID, valor de .1p, etc) • Multicastframedelivery • etc

22. Servicio Ethernet Line (E-Line) Point-to-Point Ethernet Virtual Circuits (EVC) Servers IP Voice UNI IP PBX Metro Ethernet Network CE Data CE 1 or more UNIs Video IP Voice UNI CE Data

23. Servicio Ethernet Line (E-Line) • Una E-Line puede operar con ancho de banda dedicado ó con un ancho de banda compartido. • EPL: Ethernet Private Line • Es un servicio EVC punto a punto con un ancho de banda dedicado • El cliente siempre dispone del CIR • Normalmente en canales SDH ó en redes MPLS • Es como una línea en TDM, pero con una interfaz ethernet • EVPL: Ethernet Virtual Private Line • En este caso hay un CIR y un EIR y una métrica para el soporte de SLAs (servicelevelagreement) • Es similar al FrameRelay • Se suele implementar con canales TDM compartidos ó con redes de conmutación de paquetes usando SW´s y/o routers

24. Multipoint-to-Multipoint Ethernet Virtual Circuit (EVC) Servers IP Voice UNI UNI Data IP PBX CE Metro Ethernet Network CE IP Voice IP Voice UNI CE CE UNI Data Data Servicio Ethernet LAN (E-LAN)

25. Servicio Ethernet LAN (E-LAN) • Una E-LAN puede operar con ancho de banda dedicado ó con un ancho de banda compartido. • EPLan: Ethernet Private LAN • Suministra una conectividad multipunto entre dos o más UNI´s, con un ancho de banda dedicado. • EVPLan: Ethernet Virtual Private LAN • Otros nombres: • VPLS: Virtual PrivateLanService • TLS: TransparentLanService • VPSN: Virtual PrivateSwitched Network

26. Un ejemplo: ONO

27. Un ejemplo: ONO

28. Otro ejemplo: Telefonica

29. Otro ejemplo: Telefonica

30. Virtual Private LAN Service (VPLS) • VPLS defines an architecture allows MPLS networks offer Layer 2 multipoint Ethernet Services • SP emulates an IEEE Ethernet bridge network (virtual) • Virtual Bridges linked with MPLS Pseudo Wires • Data Plane used is same as EoMPLS (point-to-point) VPLS is an Architecture PE PE CE CE CE

31. Virtual Private LAN Service • End-to-end architecture that allows MPLS networks to provide Multipoint Ethernet services • It is “Virtual” because multiple instances of this service share the same physical infrastructure • It is “Private” because each instance of the service is independent and isolated from one another • It is “LAN Service” because it emulates Layer 2 multipoint connectivity between subscribers

32. Why Provide A Layer 2 Service? • Customer have full operational control over their routing neighbours • Privacy of addressing space - they do not have to be shared with the carrier network • Customer has a choice of using any routing protocol including non IP based (IPX, AppleTalk) • Customers could use an Ethernet switch instead of a router as the CPE • A single connection could reach all other edge points emulating an Ethernet LAN (VPLS)

33. VPLS is defined in IETF VPWS, VPLS, IPLS Application ISOC L2VPN General Formerly PPVPN workgroup IAB L3VPN Internet BGP/MPLS VPNs (RFC 4364 was 2547bis) IP VPNs using Virtual Routers (RFC 2764) CE based VPNs using IPsec PWE3 IETF Ops and Mgmt Routing MPLS Pseudo Wire Emulation edge-to-edge Forms the backbone transport for VPLS Security Transport As of 2-Nov-2006

34. Classification of VPNs VPN NetworkBased CPE Based Layer 2 Layer 3 Layer 3 Ethernet P2P VPWS VPLSIPLS MPLS VPN VirtualRouter IPSec GRE Frame Relay ATM Frame Relay PPP/HDLC ATM/Cell Relay Ethernet (P2P) Ethernet (P2MP) Ethernet (MP2MP)

35. L2VPN Models L2VPN MPLS IP Like-to-LikeAny-to-Any Like-to-Like VPWSPoint-to-Point VPLS/IPLSMultipoint L2TPv3Point-to-Point PPPHDLC PPPHDLC ATMAAL5/Cell ATMAAL5/Cell Ethernet FR Ethernet Ethernet FR

36. IP LAN-Like Service (IPLS) • An IPLS is very similar to a VPLS except • The CE devices must be hosts or routers not switches • The service will only carry IPv4 or IPv6 packets • IP Control packets are also supported – ARP, ICMP • Layer 2 packets that do not contain IP are not supported • IPLS is a functional subset of the VPLS service • MAC address learning and aging not required • Simpler mechanism to match MAC to CE can be used • Bridging operations removed from the PE • Simplifies hardware capabilities and operation • Defined in draft-ietf-l2vpn-ipls

37. VPLS Components Pseudo Wires within LSP Virtual Switch Interface (VSI) terminates PW and provides Ethernet bridge function Attachment circuits Port or VLAN mode Mesh of LSP between N-PEs N-PE N-PE CE router CE router CE router CE router CE switch CE switch MPLS Core Targeted LDP between PEs to exchange VC labels for Pseudo Wires CE router Attachment CE can be a switch or router CE switch N-PE

38. Tema 2: Tecnologías LAN. EtherChannel Resilient Ethernet: HSRP

39. Etherchannel Concepts An Etherchannel combines multiple physical links into a single logical link. Ideal for load sharing or link redundancy – can be used by both layer 2 and Layer 3 subsystems… Physical View Multiple ports are defined as being part of an Etherchannel group Logical View Subsystems running on the switch only see one logical link An Etherchannel can be defined on Ethernet, Fast Ethernet, Gigabit Ethernet or 10 Gigabit Ethernet Ports

40. Etherchannel ConceptsMultichassis EtherChannel (MEC) Prior to Virtual Switch, Etherchannels were restricted to reside within the same physical switch. In a Virtual Switch environment, the 2 physical switches form a single logical network entity - therefore Etherchannels can now also be extended across the 2 physical chassis… Virtual Switch Virtual Switch Regular Etherchannel on single chassis Multichassis EtherChannel across 2 VSL-enabled Chassis

41. Resilient Ethernet • How does a workstation get a default gateway? • DHCP: gives the workstation the default gateway • IRDP (ICMP Router Discovery Protocol): extension to ICMP that allows an end-station to automatically discover a default gateway. RPs (Route Processors) periodically generate special multicast packets that announce the router’s existence to the clients every 5 to 10 minutes. Multicast packet has the RP’s address and a life-time value. Could take up to 30 minutes. • Proxy ARP: host dynamically discovers default IP address and MAC of the default gateway. When default gateway fails, traffic is dropped. After a lengthy period of time, host will re-perform the Proxy ARP, but in most situations, host will continue using same failed default gateway. • What happens to the workstation when router fails? • Host can’t communicate with other networks

42. Solution is HSRP (Hot Standby Routing Protocol) • Cisco-proprietaryprotocol • Provides Layer 3redundancy • Transparent to end stations • RP (Route Processor) monitors the status of other RPs and provides a quick failover when primary default gateway fails.

43. HSRP

44. HSRP

45. HSRP Group • A group of 2 or more RPs that represent a single default gateway. It has a virtual IP address and a virtual MAC address. If the primary RP fails, another RP takes over. • One RP can be the backup for multiple primary default gateways • Only one RP forwards data for a LAN.

46. HSRP Group • Group has the following type of RPs: • Virtual RP • Active RP • Standby RP • Other RPs • Virtual RP • Provides a single RP that is available to end stations. • Not a real RP—the IP and MAC addresses are not physically assigned to any one interface on any of the RPs in the broadcast domain

47. HSRP Group • Active RP • Responsible for forwarding all traffic destined for the Virtual RPs MAC address. • Elected in an election process—RP with highest priority is active. If priorities are same, highest IP address wins. Default priority is 100. • Only one active RP per network/subnetwork/VLAN • Standby RP • Elected in an election process • Keeps tabs on Active RP by looking for HSRP multicast messages (HSRP hellos). Hellos are sent by active RP every 3 seconds. If standby doesn’t hear any hellos for 10 seconds, it promotes itself and becomes the active RP. • Sends out its own hellos every 3 seconds so that if it fails, one of the other possible HSRP RPs in the standby group will become the standby. • Only one standby RP per network/subnetwork/VLAN

48. HSRP Group • Other HSRP RPs • Listen for hellos from standby and active RPs. • If any end-station uses a REAL MAC address of one of the RPs in the broadcast domain, that specific RP (whether active, standby or other RP) will process and forward the frame. • Each standby group must have a unique virtual IP address and a virtual MAC address. • These addresses are unique across different VLANs. • End stations perform an ARP request with the virtual IP address and get the virtual MAC address of the default gateway RP.