Transcript T2_tecnologias LAN

Tema 2:
Tecnologías LAN.
 Evolución de Ethernet.
 Ethernet para MANs
 VPLS
 EtherChannel
 Resilient Ethernet: HSRP
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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
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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
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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:
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3 - 16 Mhz, 100 ohms
4 – 20 Mhz, 100 ohms
5 – 100 Mhz , 100 ohms
5e – 350 Mhz, 100 ohms
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10BaseT Wiring & Architecture
 Star topology
 Hub or switch as concentration point.
 Switch divides into separate collision domains.
 Design concern – minimize delay between distant stations.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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 Flexible, efficient, reliable, relatively low cost end-to-end
Ethernet networks become possible.
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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.
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10 Gigabit Ethernet Architecture
 Issues of synchronization, bandwidth, and Signal-toNoise 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.
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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.
Acceso
Distribución Metro
ATM ADSL
T1/E1
FR
ATM
ATM
SONET/SDH
ATM
SONET/SDH
Optical Ethernet
EoMPLS
VPLS
EoRPR
NG-SONET(EoS)
Metro DWDM
Optical Ethernet
EoMPLS
VPLS
RPR
NG-SONET(EoS)
Metro DWDM
Metro Core
MDU
Global
Internet
STU
Empresa
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Casa
Residencial
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Evolución de Ethernet
MTU
IP ADSL
IP VDSL
EPON
EFM
Optical Ethernet
EoRPR
NG-SONET(EoS)
Global
Internet
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Servicios Metropolitanos
 Algunos servicios son:
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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
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conectividad Ethernet !!
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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
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CE
 SONET/SDH, WDM, PON, RPR, MAC-inMAC, QiQ (VLAN stack), MPLS
UNI
Metro
Ethernet
Network
(MEN)
CE
UNI
CE
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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
 Una trama enviada en un EVC puede ser enviada a uno o más
UNIs del EVC:
 Nunca será enviada de vuelta al UNI de entrada.
 Nunca será enviada a un UNI que no pertenezca al EVC.
 Las EVC´s pueden ser:
 Punto a punto (E-Line)
 Multipunto a multipunto (E-LAN)
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 Cada tipo de servicio ethernet tiene un conjunto de
atributos de servicio y sus correspondientes parámetros
que definen las capacidades del servicio.
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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.
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Atributos
 Atributos de UNI:
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 Atributos de EVC:
 Parámetros de tráfico (CIR, EIR, in, out, etc)
 Committed Information Rate (CIR)
 Excess Information Rate (EIR)
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identificador, tipo de medio, velocidad, duplex, etc
Atributo de soporte de VLAN tag
Atributo de multiplexación de servicio
Security filters attribute
etc
Parámetros de prestaciones (delay, jitter, etc)
Parámetros de Clase de Servicio (VLAN-ID, valor de .1p, etc)
Multicast frame delivery
etc
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Servicio Ethernet Line (E-Line)
Point-to-Point
Ethernet Virtual Circuits
(EVC)
Servers
UNI
IP Voice
IP PBX
Metro
Ethernet
Network
CE
Data
CE
1 or more
UNIs
IP Voice
UNI
CE
2
2
Data
Video
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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 (service level agreement)
 Es similar al Frame Relay
 Se suele implementar con canales TDM compartidos ó con redes
de conmutación de paquetes usando SW´s y/o routers
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Servicio Ethernet LAN (E-LAN)
Multipoint-to-Multipoint
Ethernet Virtual Circuit
(EVC)
IP Voice
Servers
UNI
UNI
Data
IP PBX
CE
Metro
Ethernet
Network
CE
IP Voice
CE
UNI
UNI
CE
IP Voice
Data
Data
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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 Private Lan Service
 TLS: Transparent Lan Service
 VPSN: Virtual Private Switched Network
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Un ejemplo: ONO
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Un ejemplo: ONO
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Otro ejemplo: Telefonica
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Otro ejemplo: Telefonica
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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
CE
PE
PE
CE
CE
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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
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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)
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VPLS is defined in IETF
Application
VPWS, VPLS, IPLS
ISOC
General
L2VPN
Formerly PPVPN
workgroup
IAB
L3VPN
Internet
PWE3
IETF
Ops and Mgmt
Routing
Security
As of 2-Nov-2006
Transport
MPLS
BGP/MPLS VPNs (RFC
4364 was 2547bis)
IP VPNs using Virtual
Routers (RFC 2764)
CE based VPNs using IPsec
Pseudo Wire Emulation
edge-to-edge
Forms the backbone
transport for VPLS
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Ethernet
Classification of VPNs
VPN
Network
Based
CPE
Based
Layer 2
P2P
Layer 3
VPWS
VPLS
IPLS
MPLS
VPN
Layer 3
Virtual
Router
IPSec
GRE
Ethernet (P2MP)
Ethernet (MP2MP)
Frame Relay
PPP/HDLC
ATM/Cell Relay
Ethernet (P2P)
Frame Relay
ATM
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L2VPN Models
L2VPN
MPLS
IP
Like-to-Like
Any-to-Any
Like-to-Like
VPWS
Point-to-Point
PPP
HDLC
Ethernet
VPLS/IPLS
Multipoint
PPP
HDLC
ATM
AAL5/Cell
FR
L2TPv3
Point-to-Point
Ethernet
Ethernet
ATM
AAL5/Cell
FR
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IP LAN-Like Service (IPLS)
 An IPLS is very similar to a VPLS except
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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
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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
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VPLS Components
Pseudo Wires within LSP
Virtual Switch Interface (VSI)
terminates PW and provides
Ethernet bridge function
Attachment circuits
Port or VLAN mode
CE router
Mesh of LSP between N-PEs
N-PE
N-PE
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
CE switch
N-PE
Attachment CE
can be a switch or router
Tema 2:
Tecnologías LAN.
EtherChannel
Resilient Ethernet: HSRP
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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
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An Etherchannel can be defined on Ethernet, Fast Ethernet, Gigabit Ethernet or 10 Gigabit
Ethernet Ports
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Etherchannel Concepts
Multichassis 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
Regular Etherchannel on single chassis
Virtual Switch
Multichassis EtherChannel across 2 VSLenabled Chassis
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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
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Solution is HSRP (Hot Standby Routing Protocol)
Cisco-proprietary
protocol
Provides Layer 3
redundancy
Transparent to end
stations
RP (Route Processor)
monitors the status of
other RPs and
provides a quick
failover when primary
default gateway fails.
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HSRP
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HSRP
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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.
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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
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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
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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.