Wide Area Network

1. 
Wide Area Networks
WAN

2. A Wide Area Network (WAN) is a telecommunication network that
spans a large geographic area. It usually connects two or more Local
Area Networks (LAN) by means of dedicated lines or packet/circuit
switching.

3. Characteristics of a WAN
The best example of a Wide Area Network is The
Internet!
 A WAN consists of a large numbers of nodes/hosts
that are interconnected by a subnet
 To be considered a WAN, the network must span
30+
miles

4. WAN Applications
 Wide Area Networks can be used in most any
application of transmitting voice, video, or data across
long distances
 Voice: most phone service providers merge hundreds &
thousands of analog phone calls onto a single digital
medium for transmission across town or across the country
 Video: dedicated WAN systems, such as ATM(explained
later) allow for high-quality video stream with low latency
 Data: the creation of a direct connection between twonodes
on a private WAN is much more efficient & secure that
sending data across with general Internet traffic

5. WAN Connection Types
WAN
Private
Dedicated
Leased
Lines
T1, T3,
E3….etc.
Switched
Circuit-
Switched
PSTN
ISDN
Packet-
Switched
Frame Relay
ATM
Public
Internet
Broadband
VPN
DSL
Cable
Modem

6. WAN Technologies
 A WAN can use multiple types of telecommunication mediums…
 Copper Wire
 Fiber Optic Cabling
 Radio Links
 Satellite Links
 The Data Link Layer (OSI layer 2) uses various protocols along these
mediums to describe how frames are encapsulated & transmitted.
Some common ones are…
 Public Switched Telephone Network (PSTN)
 Integrated Service Digital Network (ISDN)
 Frame Relay
 Asynchronous Transfer Mode (ATM)

7. Leased Lines
 Dedicated connections that are usually leased through a
network carrier
 Available in various capacities depending upon distance
between sites & bandwidth required.
 While very reliable, cost is considerably more than other WAN
options that utilize shared (switch) connections

8. Circuit Switching Networks
 These networks establish a dedicated circuit (or
channel)
between nodes for users to communicate
 This means that every switch along the network is
set in such a fashion that the data flows continuously
from node to node

9. Public Switched Telephone Network
 A Point-to-Point Protocol (PPP) network that may consist of more than
one leg between two hosts, however the source & destination are
connected by a direct connection
 Very popular option for using a dial-up telephone modems. This is an
example of a circuit-switched network
 Authentication is supported with Password Authentication Protocol
(PAP) & Challenge Handshake Authentication Protocol (CHAP)

10. Integrated Service Digital
Network
 International communication standard for sending
voice,
video & data via telephone wires
 Works much like PSTN, but offers higher speeds
closer to DSL rather than 56Kbps analog dial-up service

11. Packet Switching Networks
 In contrast to circuit switching, packet switching
splits traffic into packets that are individually routed
over a shared network
 DO NOT require a dedicated circuit to be
established; allows many pairs of nodes to
communicate over the same channel
 Each switch in the network routes a packet based
upon the addressing information in the header frame

12. Packet Switching Networks
(cont.)
 Connectionless Systems carry full addressing
information requiring each switch to completely evaluate
routing
 Connection-Oriented Systems predetermine the route
for each packet.
 Packets are only required to carry an identifier in the header
 Each switch has a table of predetermined routes that correspond
to different identifies stored in memory. The identifier on the
packet is checked with this listing & then assigned a route by the
router

13. Frame Relay
 Creates a private network connection through a carrier's network
 T1 Line (or other leased line) from network carrier along with a frame-
relay port. The network can be designed to include as many nodes as
needed, each connected via a Permanent Virtual Circuit (PVC). This is
an example of packet-switched network
 This option is fairly cheap because each connecting node only needs
a PVC & leased line to be connected with the WAN
 This technology is slowly
being replaced by faster services

14. Asynchronous Transfer
Mode
 ATM is a dedicated connection-oriented switching system that
organizes all data into 53-byte cells before digitally sending
them
 Each cell is processed asynchronously relative to other cells &
is queued before being multiplexed over the transmission path
 Low latency coupled with speeds up to 10Gbps, makes the
technology ideal with high intensity video data applications

15. WAN Connection Types
WAN
Private
Dedicated
Leased
Lines
T1, T3,
E3….etc.
Switched
Circuit-
Switched
PSTN
ISDN
Packet-
Switched
Frame Relay
ATM
Public
Internet
Broadband
VPN
DSL
Cable
Modem

16. Public WAN’s
The Internet
 In contrary to private WAN’s, public WAN’s have no isolation between
users/customers
 Cheaper, greater bandwidth (usually gigabit or higher)
 DSL, Cable Modem, Fiber Optic, etc.
 Companies can create virtual WAN’s by use of technologies such as
VPN that “tunnel” & encrypt traffic over the general-public Internet

17. Public WAN’s Threat
to Private WAN’s
 Virtual Private Networks (VPN) allows the creation
a ofvirtual point-to-point connection means of
dedicated connections, tunneling protocols, or traffic
encryption.
These networks are much cheaper than WAN’s & allow
more flexibility as they only need an Internet connection
to operate.
 Cloud computing is more cheaper & simple to utilize
in
most applications today.
In 2014, one survey of IT professionals indicated that nearly 50%
of those currently using WAN technologies were in the process of

19. REVIEW: WAN Connection Types
WAN
Private
Dedicated
Leased
Lines
T1, T3,
E3….etc.
Switched
Circuit-
Switched
PSTN
ISDN
Packet-
Switched
Frame Relay
ATM
Public
Internet
Broadban
d
VPN
DSL
Cable
Modem