IT Life: January 2015

Public WAN Infrastructure

An overview of public WAN technologies: DSL, Cable, Wireless, 3G/4G LTE cellular, Site-to-Site VPN, and Remote access VPNs.

DSL

Always on high-bandwidth connection
Uses existing twisted pair copper phone lines
Uses a DSL modem to convert the Ethernet signal to DSL signals
Signal from the modem is sent on the local loop to the central office.
Uses a DLS Access Multiplexer (DSLAM)
DSLAMs use TDM technology to combine multiple subscriber links into a single line typically a T3 connection.

Cable

Always on high-bandwidth connection
uses existing coaxial television network
uses cable modem to convert Ethernet signals into broadband cable frequencies
Cable broadband local loops allow for greater bandwidth then the telephone local loop
signals from the cable modem are sent on the local loop to the headend
Uses Cable Modem Termination System (CMTS) to send and receive the cable modem data
Local subscribers share the same cable bandwidth so bandwidth may be below the expected rate

Wireless

Uses unlicensed radio spectrum to send and receive data
Wireless is limited by distance
New wireless technologies seek to overcome distance limitation

Municipal WIFI

Set up by cities for use by municipal workers (police and firefighters)
Needs a wireless modem to connect that has a stronger antenna than other wireless adapters
Wireless modems are provided by the service provider for free or for a fee.

Worldwide Interoperability for Microwave Access (WIMAX)

Described in the IEEE standard 802.16
Provides high speed broadband
Works like WIFI but covers a greater area, supports more users, and higher speeds
Uses a network of WIMAX towers that are similar to cell towers
Need to subscribe to a WIMAX provider
Tower must be within 30 Miles
Requires a WIMAX receiver and encryption code to get access to the base station.

Satellite Internet

Used where cable or DSL is not available
Provides two way communication (upload/download)
Upload speed is one tenth of the 500kbps download speed
Cable/DSL have a faster download speed but satellite systems are about ten times faster than analog modems
Subscribers need a satellite dish, two modems (uplink/downlink), and coaxial between the modems and the dish.

3G/4G

Short for third generation and forth generation cellular access.
Uses cell towers for voice/data/video transfer and internet
Used when other WAN connections are not available
Uses radio waves to communicate with nearby cell towers
Devices require antennas that communicate with the much larger antenna on the cell towers
Long Term Evolution (LTE) is newer and faster call technology considered part of 4G.

VPN Technology

Public connections incur security risks. VPN mitigates the risk of a worker connecting from a remote location or a branch office connecting to corporate headquarters over the internet.

VPNs create an encrypted tunnel (VPN tunnel) through the public connection to the private network of the organization. VPN connections connect to a secured VPN server. They provide security by using advanced encryption and authentication protocols to protect data from unauthorized access. This enables organizations to use the cheaper internet connection instead of an expensive dedicated line. This eliminates expensive WAN links and modem banks. It also allows for a company to grow with out adding to its (much) own network infrastructure cutting down costs again. VPN technology is supported by broadband and DSL so mobile workers or telecommuters can easily use their own home connection.

There are two types of VPN access, Site-to-Site and Remote Access

Site-to-Site VPNs connect entire networks together over a public connection; for example, they can connect a branch office to the corporate office securely over the internet. Each side needs a VPN gateway (router, firewall, VPN concentrator, Security appliance)

Remote Access VPNs enable individual hosts to connect to a company network securely over the internet. each host typically uses a VPN software/web-based client.

Choosing a WAN Link Connection

There are many factors to consider when selecting an appropriate WAN connection. Network administrators must answer a few questions to find the WAN connection that best meets the needs of the situation.

What is the Purpose of the WAN?

Does the wan need to connect to a local branch in the same area, remote branches, or a single branch?
Will the WAN be used to connect internal employees or external partners/customers or all three?
Will the Wan provide authenticated users limited or full access to the company intranet?

What is the Geographic Scope?

is the WAN local, regional, or global?
is the WAN one to one (single branch), one to many branches, or many to many (Distributed)?

What are the traffic requirements?

What type of traffic must be supported? (data only/VoIP/ video/ large files/ streaming files) This is key in determining the quality and performance requirements.
What volume of traffic type (voice/data/video) must be supported to each destination? (Bandwidth capacity)
What quality of service is required?
What are the security requirements?

Should the WAN use a private or public infrastructure?

Private lines are more secure but are expensive. public lines are cheap and flexible but require attention to security

Should the private WAN be dedicated or switched?

Real-time high-volume transfers require special consideration and work best on a dedicated line; for example, traffic between a datacenter and the corporate head office. However, the link between corporate and a branch can use a dedicated line it may be better to use a switched connection.

What VPN access is required for a public WAN?

Which connection options are available locally?

What does the WAN connection cost?

Finally the end of chapter 2!!!! The fun begins in chapter 3 with PPP!

IT Life

Tuesday, January 20, 2015

Chapter 2: Connecting to the WAN Part 5