V Qos

Capítulo V
1.QoS
a)Bandwidth
b)Delay
c)Jitter
d)Loss

2.Características de tráfico
a)Características del tráfico de voz
b)Características del tráfico de video
c)Características del tráfico de datos

3.Planeación de las políticas de QoS

4.Herramientas de QoS
a)Queuing
b)Shaping y Policing
c)Evitar congestión
d)Eficiencia de enlace
e)Control de admisión de llamada (CAC)5.Administración de la congestión
a)Conceptos de encolamientos en ruteadores

6.Conceptos de clasificación y marcado
a)Campos de QoS en el encabezado de IP: Precedencia y DSCP
b)Clase de servicio de LAN (CoS)
c)Problemas de clasificación cuando se usan VPNs

7.Traffic Policing y Shaping
a)Cuando y donde usar Shaping y Policing
b)Como trabaja Shaping
c)Como trabaja Policing

8.Políticaspara evitar la congestión y tirado de paquetes
a)Conceptos para evitar la congestión y Random Early Detection (RED)
b)Weighted RED (WRED)

9.Herramientas para eficientar el enlace
a)Compresión del encabezado
b)Fragmentación del enlace e intercalado




1.QoS
Quality of Service (QoS) refers to the capability of a network to provide better service to selected network traffic over varioustechnologies, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks, SONET, and IP-routed networks that may use any or all of these underlying technologies. The primary goal of QoS is to provide priority including dedicated bandwidth, controlled jitter and latency (required by some real-time and interactive traffic), and improved loss characteristics. Also important ismaking sure that providing priority for one or more flows does not make other flows fail. QoS technologies provide the elemental building blocks that will be used for future business applications in campus, WAN, and service provider networks.

a)Bandwidth
The amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits persecond(bps) or bytes per second. For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).

b)Delay
Delay is the time taken from point-to-point in a network. Delay can be measured in either one-way or round-trip delay. One-way delay calculations require expensive sophisticated test gear and are beyond the budget and expertise of most enterprise customers. However,measuring round-trip delay is easier and requires less expensive equipment. To get a general measurement of one-way delay, measure round-trip delay and divide the result by two. VoIP typically tolerates delays up to 150 ms before the quality of the call is unacceptable.

c)Jitter
Jitter is the variation in delay over time from point-to-point. If the delay of transmissions varies too widely in a VoIPcall, the call quality is greatly degraded. The amount of jitter tolerable on the network is affected by the depth of the jitter buffer on the network equipment in the voice path. The more jitter buffer available, the more the network can reduce the effects of jitter.

d)Loss
Packet loss is losing packets along the data path, which severely degrades the voice application.
Prior to deployingVoIP applications, it is important to assess the delay, jitter, and packet loss on the data network in order to determine if the voice applications work. The delay, jitter, and packet loss measurements can then aid in the correct design and configuration of traffic prioritization, as well as buffering parameters in the data network equipment.






2.Características de tráficoa)Características del tráfico de voz
✓ Latency menor o igual a 150 ms
✓ Jitter menor o igual a 30 ms
✓ Loss menor o igual a 1%
✓ 17-106 kbps guaranteed priority bandwidth per call
✓ 150 bps (+layer 2 overhead) guarteed bandwidth voice control traffic per call

b)Características del tráfico de video
✓ Latency igual a 150 ms
✓ Jitter igual a 30 ms
✓ Loss igual a 1%...