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Periodo 2013
GESTION DE REDESAREA DE LA ENERGA LAS INDUSTRIAS
Y LOS RECURSOS NATURALES NO
RENOVABLESCARRERA DE INGENIERA EN SISTEMAS
GESTION DE REDES Parte III
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MEDIOS FISICOS
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Se enfocar a los medio de red ms comunes y sus caractersticas,describiremos entonces:
Cable STP
Cable UTP
Cable Coaxial
Fibra pticaAtmsfera (redes inalmbricas)
MEDIOS FISICOS
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CableSpecifications
Cables have different specifications and expectations pertaining toperformance.
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Coaxial Cable
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Coaxial Cable
Advantages: Requires fewer repeaters than twisted pair Less expensive than fiber It has been used for many years for many types of
data communication, including cable television Disadvantages:
More expensive and more difficult to install thantwisted pair
Needs more room in wiring ducts than twisted pair
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Unshielded Twisted Pair (UTP)
Unshielded twisted-pair cable (UTP) is a four-pair wiremedium used in a variety of networks.
TIA/EIA-568-A/B contains specifications governing cable
performance. RJ-45 connector
When communication occurs, the signal that is transmitted bythe source needs to be understood by the destination.
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Shielded Twisted Pair (STP and ScTP)
Shielded twisted-pair cable (STP) combines the techniques of
shielding, cancellation, and twisting of wires. Each pair of wires is wrapped in metallic foil. The four pairs of wires are wrapped in an overall metallic braid or
foil. Screened UTP (ScTP), also known as Foil Twisted Pair (FTP).
ScTP is essentially UTP wrapped in a metallic foil shield, or screen.
STP Shielded Twisted Pair ScTP Screened Twisted Pair
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Fiber Optic Cabling
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ST and SC Connectors
The type of connector most commonly used withmultimode fiber is the Subscriber Connector (SC
connector); LC connector smaller than the sc , FCReplacement by ST Y SC
On single-mode fiber, the Straight Tip (ST)connector is frequently used. MT-Array (array defiber)
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Fiber Optic Patch Panel
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Medio inalmbrico Ondas electromagnticas, que pueden recorrer el
vaco del espacio exterior y medios como el aire.
No necesitan un medio fsico para propagarse. Muy verstil para el desarrollo de redes. La aplicacin ms comn de las comunicaciones de
datos corresponde a los usuarios mviles. Cualquier persona o elemento que necesite
comunicar datos a travs de una red sin laslimitaciones de la FO o el cobre .
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Wireless WAN Standards IEEE is the prime issuer of standards for wireless
networks. 802.11 standard is Direct Sequence Spread Spectrum
(DSSS). DSSS applies to wireless devices operating within a 1
to 2 Mbps range.
802.11b may also be called Wi-Fi or high-speedwireless and refers to DSSS systems that operate at 1, 2,5.5 and 11 Mbps. The majority of 802.11b devices still fail to match the
11 Mbps throughput and generally function in the2 to4 Mbps range.
802.11acovers WLAN devices operating in the 5 GHZtransmission band. throughput 54 Mbit/s
802.11g provides the same throughout as 802.11a butwith backwards compatibility for 802.11b devices.
802.11 n provides throughout as 300 Mbps
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Wireless devices
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How wireless LANscommunicate
Since radio frequency (RF) is a sharedmedium, collisions can occur just as theydo on wired shared medium.
The major difference is that there is nomethod by which the source node is ableto detect that a collision occurred.
For that reason WLANs use Carrier
Sense Multiple Access/CollisionAvoidance (CSMA/CA). This is somewhat like Ethernet
CSMA/CD.
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Prctica: Utilizar el software Packet Tracer 5.0 o mas
para simulacin de una red de campus condiferentes tipos de medios de comunicacin
con WLAN con APs y laptops.
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Tecnologas de la Capa 2 Desempea funciones especficas como:
Proporcionar una interfaz de servicio biendefinida para la capa de red.
Determinar la manera como los bits seagrupan en tramas, suministrando trnsitode datos confiable a travs del enlace fsicoutilizando las direcciones MAC.
Manejar los errores de transmisin y Regularel flujo de tramas para que los
receptores lentos no sean saturados por
transmisores rpidos.
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Capa de Enlace de Datos
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Implementaciones Prcticas Token Ring, FDDI y Ethernet. Todas especifican
aspectos de la Capa 2 (LLC control de enlacelgico, denominacin, entramado y MAC), as comotambin aspectos de los componentes desealizacin y de medios de la Capa 1.
Ethernet: topologa de bus lgica y en estrella fsicao en estrella extendida.
Token Ring: topologa de anillo lgica y unatopologa fsica en estrella.
FDDI: topologa de anillo lgica y topologa fsica deanillo doble.
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Entramado o Enmarcado de
Datos Para entregarservicios a la Capa de red, la
Capa de enlace de Datos debe utilizarlos
servicios proporcionados por la Capa fsica. La capa 1 acepta un flujo de bits en bruto y lo
entrega al destino o intenta hacerlo y nogarantiza ausencia de errores.
El # de bits recibidos puede ser mayor, menoroigualque el # de bits transmitidos.
Es responsabilidad de la Capa de enlace deDatos detectar y corregir estos errores.
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Entramado o Enmarcado deDatos
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Es un concepto terico, que ayuda a entender la tec-nologa y las tramas (802.3, 802.5, FDDI), lospaquetes (IP) y los segmentos (TCP y UDP)especficos.
Tiene secciones llamadas campos formados por bytes campo de inicio de trama
campos de direccin campo de longitud/tipo/control campo de datos campo de secuencia de verificacin de trama
campo de fin de trama
Formato de Trama Genrica
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Tecnologas de la Capa 2
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802.0 SEC
802.1 High Level Interface (HILI)
802.2 Logical Link Control (LLC)
802.3 CSMA/CD Working Group
802.4 Token Bus
802.5 Token Ring
802.6 Metropolitan Area Network (MAN)
802.7 BroadBand Technical Adv. Group (BBTAG)
802.8 Fiber Optics Technical Adv. Group (FOTAG)
802.9 Integrated Services LAN (ISLAN)
802.10 Standard for Interoperable LAN Security (SILS)
802.11 Wireless LAN (WLAN)
802.12 Demand Priority
802.14 Cable-TV Based Broadband Communication Network
802.15 Wireless Personal Area Network (WPAN)
802.16 Broadband Wireless Access (BBWA)
RPRSG Resilient Packet Ring Study Group (RPRSG)
IEEE 802 Committees
IEEE 802.3 - 10 Mbps
IEEE 802.3u - 100 Mbps
IEEE 802.3z - 1000 Mbps
IEEE 802.3ab - 1000 Mbps
IEEE 802.11
IEEE 802.11a
IEEE 802.11b WiFi
IEEE 802.11g
IEE 802.11 n
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LAN: Ethernet
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Tipos de Ethernet
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Tipos de Ethernet
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Frames Ethernet
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Frames Ethernet 802.3 con 802.2
DSAP (Destination Service Access Point) y SSAP (Source Service Access
Point)
Service Access Point
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100-Mbps Ethernet
100-Mbps Ethernet is also known as Fast Ethernet
100BASE-TX is copper UTP
100BASE-FX is multimode optical fiber
Frame format
100-Mbps frame format is the same as the 10-Mbps frame
Parts of the transmission process
Two separate encoding steps are used
The first part of the encoding uses a technique called
4B/5B
The second part of the encoding is the actual line
encoding specific to copper or fiber
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4B/5B Cada 4 bits de datos se codifica en
cdigos de 5-bit los cdigos de 5 bits son seleccionados
para tener no mas de un 0 inicial y no masde dos 0s finales. As, nunca se tienen mas de tres 0s
consecutivos
La palabra de cdigo de 5 bit sontransmitidas usando NRZI Se logra 80% de eficiencia
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1000-Mbps Ethernet
1000-Mbps Ethernet or Gigabit EthernetTransmission
Fiber and copper media
The 1000BASE-X IEEE 802.3z
Specifies 1 Gbps full duplex over optical fiber
1000BASE-TX, 1000BASE-SX, and 1000BASE-LX
Frame Format Same format used for 10 and 100-Mbps Ethernet
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1000-Mbps Ethernet
1000BASE-T (IEEE 802.3ab) was developed toprovide additional bandwidth for:
Intra-building backbones
Inter-switch links
Server farms Connections for high-end workstations
Supports both half-duplex and full-duplex
Fiber-based Gigabit Ethernet (1000BASE-X)
Uses 8B/10B encoding (similar to 4B/5B)
Uses encoding ZRZI Non Return to Zero Invertive
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1000Base-LX/SX
NRZ signals are pulsed into the fiber Short-wavelength (1000BASE-SX ) Long-wavelength (1000BASE-LX)
Separate fibers
Transmitting (Tx)
Receiving (Rx)
Inherently full duplex
Gigabit Ethernet is the dominant technology for: Backbone installations
High-speed cross-connects
General infrastructure
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10 GigabitEthernet
10GBASE-SR Short distances, supports a range between 26 m to 82 m 10GBASE-LX4
Uses wide wavelength division multiplexing (WWDM)
240 m tHo 300 m over multimode fiber
10 km over single-mode fiber 10GBASE-LR and 10GBASE-ER
Support 10 km and 40 km over single-mode fiber 10GBASE-SW, 10GBASE-LW, and 10GBASE-EW
Known collectively as 10GBASE-W
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Future of EthernetFuture of Ethernet
The future of networking media is three-fold:1.Copper (up to 10-1000 Mbps, perhaps
more)
2.Wireless (approaching 1000 Mbps, perhaps
more)3.Optical fiber (currently at 10,000 Mbps and
soon to be more)
Copper and wireless media have certainphysical and practical limitations
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Ejercicios Extra-clase de anlisis de trficoutilizando la herramienta Wireshark
IP, ETHERNET, UDP, TCP, ARP, http, https
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Dispositivos de Capa 2
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Prove el puerto para la conexin dered
NICs
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Factores de Seleccin de la
NIC Al elegir la NIC se debe tener encuenta:
tipo de red Ethernet (10/100/1000 Mbps)
tipo de medios UTP, F.O., Wireless
tipo de bus del sistema
PCI, PCMCIA, USB
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PUENTES (BRIDGE) Dispositivo de capa 2 conecta
dos segmentos de LAN Trabajan a nivel de software
generando latencia Filtrar el trfico de una LAN
Verifica la direccin de cadadispositivo de la LAN
Crea una lista de MAC paratoma de decisiones
Cada NIC tiene una direccinMAC exclusiva El puente conecta solamente
dos segmentos a la vez Los routers y los switches han
desplazado al puente
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SWITCH
Dispositivo de la capa 2 Puente multipuerto
Toman decisiones basadosen las direcciones MAC
LANs mucho ms eficiente
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Segmenta una red endominios de colisin tantoscomo puertos activos posea
Conmutan" datos slodesde el puerto de origen alde destino
Suministra a cada puerto elancho de banda total
SWITCH
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Trabaja conmutando tramas de datos Aprende direcciones, reenviar, filtrar paquetes y
evitar bucles Controlar el trficos de mltiples segmentos
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Layer 2 and layer 3 switching
A layer 3 switch is typically a layer 2 switch that includes arouting process
Layer 3 switching has many meanings and in many cases isjust a marketing term.
Layer 3 switching is a function of the network layer. The Layer 3 header information is examined and the packet is
forwarded based on the IP address.
Symmetric and asymmetric
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Symmetric and asymmetricswitching
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Tres mtodos de conmutacin
Store-and-forward The entire frame is receivedbefore any forwarding takes place. The destination and source addresses are read and
filters are applied before the frame is forwarded. CRC (count of redundancy cyclical)| Check done is
forwarded Cut-through The frame is forwarded through the
switch before the entire frame is received. This mode decreases the latency of the
transmission, but also reduces error detection.
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Free of fragmenteste es una modificacion de metodo de corte, elswitch lee los primeros 64 bytes antes de transmitir la trama.
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Dominios de Broadcast Todos los hosts conectados al mismo
switch permanecen en el mismodominio de broadcast
Un broadcast desde un nodo ser vistopor todos los otros nodos conectadosen el mismo switch
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Dominios de Broadcast Todos los hosts conectados al mismo
switch permanecen en el mismodominio de broadcast
Un broadcast desde un nodo ser vistopor todos los otros nodos conectadosen el mismo switch
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APRENDIZAJE DE DIRECCIONES
Un switch crea circuitos Virtuales entresegmentos identificando lasdirecciones MAC de destino asociada
a un puerto Cuando un switch se inicia no posee
datos MAC por lo que inunda todos los
puertos para obtener la MAC
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Segmentacin con Routers
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Tarea Extra-Clase:Realizar un cuadro comparativo de
caractersticas tcnicas & estndares de 3
switches de diferentes fabricantes (Cisco,Enterasys, HP, D-link, TPLINK,
TRENDNET, ETC...).
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Capa de RedEnrutamiento y Direccionamiento
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Importancia de la Capa de
Red Identificacin
Segmentacin Comunicacin entre redes Determinacin de Ruta
Direccionamiento
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Airport
School
Gas Station
Hospital
Factory
Train Station
FD
Fire Department
Stadium
Sidew
City Str
Intersta
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Airport
School
Gas Station
Hospital
Factory
Train Station
FD
Fire Department
Stadium
Sidewalk
City Street
Interstate
Bomberos a la Escuela
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F
C
G
E
B
DA
Internet
56
T1 1.5Mbps
T3 45Mbps
A
D
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F
C
G
E
B
DA
Internet
56
T1 1.5Mbps
T3 45Mbps
Red C a Red G
B
C
D
E
FG
Direccionamiento (Capa de
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Direccionamiento (Capa deRed)
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Capa de Red
Direcciones IP dentro del
Encabezado IP