6-9 Yu

The primary use of NAT

In NAT terminology, the set of networks that is subject to translation

In NAT terminology, all networks other than the ones subject to translation

The perspective from which NAT terminology is always applied

The address of the device which is being translated by NAT

The address of the destination device

Any address that appears on the inside portion of the network

Any address that appears on the outside portion of the network

Uses a one-to-one mapping of local and global addresses

Uses a pool of public addresses and assigns them on a first-come, first-served basis

Maps multiple private IPv4 addresses to a single public IPv4 address or a few addresses

The reason NAT increases forwarding delays

The reason NAT complicates the use of tunneling protocols like IPsec

Command to display all static translations that have been configured and dynamic translations created by traffic

Command to clear dynamic entries before the timeout has expired

Developed with the intention of making NAT for IPv4 unnecessary

Similar to RFC 1918 private addresses in IPv4 but have a different purpose

Provides for protocol translation between IPv4 and IPv6

Required to connect beyond the boundary of the LAN

A connection that is dedicated to a single customer

A connection typically provided by an ISP or telecommunications service provider using the internet

Logical topologies used to implement WANs

Provides redundancy and increases network availability by negotiating separate SLAs with two different service providers

Enables the company to use the internet to securely connect with employees and facilities around the world

Recognized authorities that define and manage modern WAN standards

Layer 1 optical fiber protocol standards

Layer 2 protocols that define how data will be encapsulated into a frame

Transmits bits sequentially over a single channel

Simultaneously transmits several bits using multiple wires

The two most common types of circuit-switched WAN technologies

Common types of packet-switched WAN technologies

Define how to transfer multiple data, voice, and video communications over optical fiber using lasers or LEDs over great distances

Provided circuit-switched connections

A circuit-switching technology that enables the PSTN local loop to carry digital signals

Segments data into packets that are routed over a shared network

A simple Layer 2 NBMA WAN technology used to interconnect enterprise LANs

A technology built on a cell-based architecture capable of transferring voice, video, and data through private and public networks

Modern WAN connectivity options

A high-performance service provider WAN routing technology capable of encapsulating all types of protocols to interconnect clients

An alternative to using dedicated WAN options

Examples of wired broadband connectivity

Examples of wireless broadband

A high-speed, always-on connection technology that uses existing twisted-pair telephone lines to provide IP services

A high-speed always-on connection technology that uses a cable company coaxial cable to provide IP services

Newer developments in wireless technology

Routed through the internet from the private network of the company to the remote site or employee host

ISP connectivity options

Keeps data confidential while it is transported across the public network by encrypting traffic

Benefits of VPNs

Lets remote and mobile users securely connect to the enterprise by creating an encrypted tunnel using IPsec or SSL

Used to connect networks across an untrusted network such as the internet

The VPN terminating device in a site-to-site VPN

A non-secure site-to-site VPN tunneling protocol

A Cisco software solution for easily building multiple, dynamic, scalable VPNs

Simplifies the configuration process required to support multiple sites and remote access

Protects and authenticates IP packets between source and destination

Layers at which IPsec can protect traffic

Provided by the IPsec framework

Protocols used by IPsec to encapsulate packets

Determines the degree of confidentiality in IPsec

Provides a way for two peers to establish a shared secret key over an insecure channel

Created by voice and live video transmissions, prompting a need for Quality of Service (QoS)

What happens without QoS mechanisms in place during congestion

The reason queuing packets causes delay

Two types of delays

Sources of delay

The variation in the delay of received packets

Traffic that is smooth and benign, but sensitive to drops and delays

Traffic that is demanding, bursty, greedy, drop sensitive, and delay sensitive

Traffic that uses TCP applications, can retransmit data, and is not sensitive to drops and delays

When the QoS policy implemented by the network administrator becomes active

A congestion management tool that can buffer, prioritize, and reorder packets before transmission

Buffers and forwards packets in the order of their arrival with no concept of priority

An automated scheduling method that provides fair bandwidth allocation by applying weights to identified traffic

Extends standard WFQ functionality to provide support for user-defined traffic classes based on match criteria

Brings strict priority queuing (PQ) to CBWFQ

The three models for implementing QoS

Architecture model developed to meet the needs of real-time applications

Specifies a simple and scalable mechanism for classifying and managing network traffic, overcoming previous model limitations

The three categories of QoS tools

Determines the class of traffic to which packets or frames belong

Methods of classifying traffic flows at Layer 2 and 3

Used to classify traffic at Layers 4 to 7

Includes queuing and scheduling methods where excess traffic is buffered or queued

Helps monitor network traffic loads to anticipate and avoid congestion at bottlenecks

A possible congestion avoidance solution included in Cisco IOS QoS