Wireless Communication and Networking.

Presentation OutlineWireless Communications

Wireless Technology overview

The IEEE 802.11 WLAN Standards

Secure Wireless LANs

Migrating to Wireless LANs (Cutting the cord)

WIRELESSAny type of electrical or electronic operation without use of wires

Wireless connections use air to connect sending and receiving devices

Channel is a division in transmission medium

COMMUNICATIONIt is transmission of signals i.e. sending of electromagnetic waves by electronic transmitters

WIRELESS COMMUNICATIONCommunication networks are generally implemented with some type of remote information transmission system that uses electromagnetic waves.

Wireless communication may be via:

Radio frequency communication

Microwave communication

Infrared short range communication

Types of NetworksLAN – Local Area Network

MAN – Metropolitan Area Network

WAN – Wide Area Network

GSM – Global System for Mobile Communications

PCS – Personal Communication Services

Wi-Fi – Wireless Fidelity

GPRS – General Packet Radio Service

AMPS- Advanced Mobile Phone System

Wireless NetworkWhat is a wireless network?◦ A technology that enables two or more entities to communicate without

network cabling

Common TopologiesThe wireless LAN connects to a wired LAN

There is a need of an access point that bridges wireless LAN traffic into the wired LAN.

The access point (AP) can also act as a repeater for wireless nodes, effectively doubling the maximum possible distance between nodes.

Common TopologiesComplete Wireless Networks

The physical size of the network is determined by the maximum reliable propagation range of the radio signals.

Referred to as ad hoc networks

Are self-organizing networks without any centralized control

Suited for temporary situations such as meetings and conferences.

How do wireless LANs work?Wireless LANs operate in almost the same way as

wired LANs, using the same networking protocols

and supporting the most of the same

applications.

How are WLANs Different?They use specialized physical and data link protocols

They integrate into existing networks through access points which provide a bridging function

They let you stay connected as you roam from one coverage area to another

They have unique security considerations

They require different hardware

They offer performance that differs from wired LANs.

Physical and Data Link LayersPhysical Layer:

The wireless NIC takes frames of data from the link layer, scrambles the data in a predetermined way, then uses the modified data stream to modulate a radio carrier signal.

Data Link Layer:

Uses Carriers-Sense-Multiple-Access with Collision Avoidance (CSMA/CA).

Integration With Existing NetworksWireless Access Points (APs) - a small device that bridges wireless traffic to your network.

Most access points bridge wireless LANs into Ethernet networks.

Integration With Existing Networks

Roaming Users maintain a continuous connection as they roam from one physical area to another

Mobile nodes automatically register with the new access point.

Methods: DHCP, Mobile IP

IEEE 802.11 standard does not

address roaming, you may need

to purchase equipment from one

vendor if your users need to roam

from one access point to another.

What is 802.11?A family of wireless LAN (WLAN) specifications developed by a working group at the Institute of Electrical and Electronic Engineers (IEEE)

Defines standard for WLANs using the following four technologiesFrequency Hopping Spread Spectrum

Direct Sequence Spread Spectrum

Infrared

Orthogonal Frequency Division Multiplexing

Versions: 802.11a, 802.11b, 802.11g, 802.11n

WIFI Standard..802.11a

offers speeds with a theoretically maximum rate of 54Mbps in the 5 GHz band

Pros of 802.11a - fast maximum speed; regulated frequencies prevent signal interference from other devices

Cons of 802.11a - highest cost; shorter range signal that is more easily obstructed

802.11b July 1999

offers speeds with a theoretically maximum rate of 11Mbps at in the 2.4 GHz spectrum band

Pros of 802.11b - lowest cost; signal range is good and not easily obstructed

Cons of 802.11b - slowest maximum speed; home appliances may interfere on the unregulated frequency band

WIFI Standard..802.11g 2002 and 2003

is a new standard for data rates of up to a theoretical maximum of 54 Mbps at 2.4 GHz.

Pros of 802.11g - fast maximum speed; signal range is good and not easily obstructed

Cons of 802.11g - costs more than 802.11b; appliances may interfere on the unregulated signal frequency

802.11n (Recently)

Specifications providing for up to 300 Mbps of network bandwidth. 802.11n also offers somewhat better range over earlier Wi-Fi standards due to its increased signal intensity

MIMO technology(Multiple Input Multiple output) MESH

http://compnetworking.about.com/od/wireless/f/80211n-300-mbps.htm

WIFI StandardPros of 802.11n - fastest maximum speed and best signal range; more resistant to signal interference from outside sources

Cons of 802.11n - standard is not yet finalized; costs more than 802.11g.

Operating Frequency2.4 GHz

Indoor AP(Access Point) operate 2.4GHz due good penetration power.

5 GHz

Outdoor AP(Access Point) operate on 5GHz for maximum coverage.

Problem. If we have to install more than One AP at a single location what about the Frequency interference?

Frequency ChannelDivision of Frequency

To Avoid from interference we use non-overlapping frequency channel of same frequency band

(Band 2.4GHz , 5.0 GHz)

Different Devices Support different number of frequency channel.

2.4GHZ ChannelCHANNEL NUMBER LOWER FREQUENCY

MHZCENTER FREQUENCY

MHZUPPER FREQUENCY

MHZ

1 2401 2412 2423

2 2404 2417 2428

3 2411 2422 2433

4 2416 2427 2438

5 2421 2432 2443

6 2426 2437 2448

7 2431 2442 2453

8 2436 2447 2458

9 2441 2452 2463

10 2451 2457 2468

11 2451 2462 2473

12 2456 2467 2478

13 2461 2472 2483

14 2473 2484 2495

Non-overlapping Frequency Channel…

Non-overlapping Frequency Channel

Wireless Networking DevicesAP

WLC (WIRELESS LAN CONTROLLER)

CPI (CISCO PRIME INRESTRUCTRE)

BRIDGE

AP (ACCESS POINT)Is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards. The AP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself. AP emit the signal called SSID(Service Set Identifier).

AP ROLE

RAP (special scenario)

MAP (Special scenario)

Client

Repeater

RAP (Remote Access Point)Provide up link to it’s nearest AP

RAP is connected via Bridge to the NOC (network operation Center)

RAP also provide the services to end client

MAP (Mesh Access Point)Get uplink from RAP.

Provide services to end user

CLIENT

Single AP ,decently connected with network switch.

Bridge

A Bridge is used to provide uplink to a remote AP via Wireless

Repeater/Booster

Repeater and Booster are used to amplify the Signal on the behalf of other AP

WLC (Wireless LAN Controller)…Assign the role of RAP & MAP

Control the traffic of Wireless Device

Auto Shifting of RAP (Incase Parent RAP is down)

Has ability to differentiate between Voice and DATA

Traditional roles of access points, such as association or authentication of wireless clients, are done by the WLC

CAPWAP (Controlling and provisioning of wireless AP) IOS of WLC

CAPWAP is used to communicate between the controller and other lightweight access points on the network

WLC (Wireless LAN Controller)All the client (802.11) packets are encapsulated in a LWAPP packet by the AP and sent to the WLC.

Security Measures SSID hiding

A simple but ineffective method to attempt to secure a wireless network is to hide the SSID (Service Set Identifier).This provides very little protection against anything but the most casual intrusion efforts.

MAC ID filtering

One of the simplest techniques is to only allow access from known, pre-approved MAC addresses. Most wireless access points contain some type of MAC ID filtering. However, an attacker can simply sniff the MAC address of an authorized client and spoof this addresses.

Static IP addressing

Typical wireless access points provide IP addresses to clients via DHCP. Requiring clients to set their own addresses makes it more difficult for a casual or unsophisticated intruder to log onto the network, but provides little protection against a sophisticated attacker

802.11 security

IEEE 802.1X is the IEEE Standard Authentication mechanisms to devices wishing to attach to a Wireless LAN.

WEP (Wired Equivalent Privacy)

The 64-bit WEP data encryption method allows for a five-character (40-bit) input. Additionally, 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. data encryption method allows for a five-character (40-bit) input. Additionally, 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key.

WPAv1 (Wi-Fi Protected Access)

The Wi-Fi Protected Access (WPA and WPA2) security protocols were later created to address the problems with WEP.WAP and WAP2 support up to 14 character.

http://en.wikipedia.org/wiki/Wi-Fi_Protected_Accesshttp://en.wikipedia.org/wiki/Wi-Fi_Protected_Access

M Sabir SaeedICT-TRAININGG

ICT-INTEGRATORS

LAHORE PAKISTAN