networking with remote clients and servers 1224573519876521 8

8/14/2019 Networking With Remote Clients and Servers 1224573519876521 8

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Chapter 7

Networking with Remote Clients

and Servers


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Remote Node

Today remote nodes connect via ISDN,DSL, cable modem, and Virtual Private

Networking (VPN) across the Internet, inaddition to dialing up using the plain oldtelephone system (POTS).

When connecting via remote node, a

computer makes a connection through apublic network to a remote access server(RAS).


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Remote Node

The remote access server then acts as a

router, exchanging traffic between the

remote computer and the network. This enables the remote computer to act as

though it is a network node, able to transfer

files, access database information andapplications, and print to network printers.


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Remote Node


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Remote Node

Remote computing is typically slow!

When the remote node accesses applications from a

network location, the application must first download to

the remote node before it is processed.Updates made to data must be uploaded across that slow

link as well.

A server handles requests the same way regardless of

whether the node is local or remote.


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Remote Node

Remote node computing is simply a point-

to-point link. The remote node connects

directly to a remote access server via anintervening network.


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Remote Node


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Remote Node

Remote nodes differ from local nodes in only

one way: Data travels through a modem to

access the network in a remote node when it

uses a dialup connection.

Data travels through a network interface card

(NIC) to access the network in a local node.

Therefore, a remote node simply treats itsmodem as though it were a NIC.


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Point-to-Point Connections

with PPP

When you create a dialup connection to RAS,

you must use a protocol to communicate.

The protocol most often used to create thepoint-to-point connection across the

telephone network is the aptly named Point-

to-Point Protocol (PPP).

It is based on an older protocol know as theSerial Line Internet Protocol (SLIP).


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with PPP

PPP offers several advanced capabilities.

When it is used to connect with a remote network, it

encapsulates the upper-layer protocols. This process enables a remote node to appear to be

connected locally.

PPPs link-control ability indicates when a

connection is poor, providing for automatic

termination and redialing.


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with PPP

PPP supports both Password Authentication

Protocol (PAP) and Challenge Handshake

Authentication Protocol (CHAP), which both

prompt users to log on to establish a

connection using encryption or clear text

passwords.


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with PPP


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Using DSL for Remote Node

ADSL

G.Lite (DSL lite)

HDSLVDSL


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Remote Access Service (RAS)

When you dial into a network as a remote

node, you log into a remote access server.

This is often the same server that providesremote node services across the Internet, via

tunneling protocols.

A variety of remote access servers is

available.


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Remote Access Service (RAS)


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Tunneling to a Virtual Private

Network (VPN)

VPN describes remote nodes that access a

network via the Internet in a secure fashion.

That security is provided by tunneling

protocols, along with encryption.

Many encryption schemes can encode data

with strengths up to 128 bits, an encryption

strength that virtually prevents decryptionaltogether.


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Network (VPN)

VPN is available to clients who connect to theInternet through nearly any type of link.

Whether the client connects via ISDN, DSL, cablemodem, or dialup line, a VPN session can usually

be created. VPN creates a virtual point-to-point connection to

the RAS. Tunneling is driven by the need to protect that virtual

point-to-point link from being interrupted oreavesdropped upon. Tunneling works by encapsulating data within IP

packets in an encrypted format.


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Network (VPN)


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Point-to-Point Tunneling

Protocol (PPTP)

Point-to-Point Tunneling Protocol (PPTP)

takes its name from PPP because it uses

PPP frames in its tunneling process.

PPTP encapsulates PPP frames within IP

datagrams, which are then transmitted across

the Internet.


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Remote Control

Remote control computing overcame some of

the issues with remote node computing.

Because the application ran only on the LAN-

connected computer, the remote computer

didnt need to be compatible with the network

applications, nor did it require any additional

hardware.


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Remote Control


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Independent Computing

Architecture from Citrix

Citrix developed its ICA protocol to facilitate

remote control sessions.

The protocol runs within the upper layers of

the OSI reference model, including the

application, presentation, and session layers.

It establishes the session, maintains it, and

terminates it.


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During the session, ICA carries keystrokes,

mouse clicks, and graphical data in the form of

compressed draw commands.

ICA is highly optimized in that it will update

only the graphical data that has changed on

the screen.

The protocol also allows file transfers betweenthe local and remote computers.


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ICA requires very little bandwidth and can

provide solid performance over a 20-Kbps

connection.

This means that the average computer using

a 56-Kbps modem connection will experience

exceptional performance with an ICA

session.


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Microsoft Remote Desktop

Protocol (RDP)

Remote Desktop Protocol (RDP) offers much

the same type of service as ICA.

It supplies the transport for keystrokes,

mouse clicks, and display data for a server

providing sessions to a thin client application.


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Microsoft Remote Desktop

Protocol (RDP)

RDP is limited in the protocols it will run

across; theres no direct dial method.

RDP clients will operate only across a TCP/IP

network.

If you need to run remote sessions across a

network that is solely IPX/SPX or NetBEUI,

you would be required to use CitrixMetaFrame.

networking with remote clients and servers 1224573519876521 8

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