1. The world is going to wireless …

2. Wireless Networking
CCNP Switch
Hossein Shamloo

3. IEEE
In IEEE terminology, any group of wireless devices is known as a service set. The devices must share a common service set identifier (SSID), which is a text string included in every frame sent. If the SSIDs match across the sender and receiver, the two devices can communicate.

4. IEEE
Network Types

5. A) IBSS (Independent basic service set)
IEEE Network Types
A) IBSS (Independent basic service set)
The standards allow two or more wireless clients to communicate directly with
each other, with no other means of network connectivity

6. B) BSS (basic service set)
IEEE Network Types
B) BSS (basic service set)
An BSS centralizes access and control over a group of wireless devices by placing
an access point (AP) as the hub of the service set.
Any wireless client attempting to use
the wireless network must first arrange a membership with the AP

7. B) BSS (basic service set)
IEEE Network Types
B) BSS (basic service set)
Requirement for membership :
■ A matching SSID
■ A compatible wireless data rate
■ Authentication credentials

8. B) BSS (basic service set)
IEEE Network Types
B) BSS (basic service set)
Membership with the AP is called an association
The client must send an association request
message, and the AP grants or denies the request by sending an association reply
message

9. B) BSS (basic service set)
IEEE Network Types
B) BSS (basic service set)
Keep in mind that regardless of the association status, any PC is capable of listening
to or receiving the frames that are sent over a wireless medium. Frames are freely available
over the air to anyone who is within range to receive them

10. B) BSS (basic service set)
IEEE Network Types
B) BSS (basic service set)
An AP manages its wireless network, advertises its own existence so that clients can associate, and controls the communication process
For example, recall that every data frame sent successfully (without a collision) over a wireless medium must be acknowledged. The AP is responsible for sending the acknowledgment frames back to the sending stations

11. B) BSS (basic service set)
IEEE Network Types
B) BSS (basic service set)
An AP manages its wireless network, advertises its own existence so that clients can associate, and controls the communication process
For example, recall that every data frame sent successfully (without a collision) over a wireless medium must be acknowledged. The AP is responsible for sending the acknowledgment frames back to the sending stations

12. IEEE Network Types
An AP can also uplink into an Ethernet network because it has both wireless and wired capabilities.

13. IEEE Network Types
B) ESS (extended service set)

14. B) ESS (extended service set)
IEEE Network Types
B) ESS (extended service set)
If APs are placed at different geographic locations, they can all be interconnected
by a switched infrastructure

15. B) ESS (extended service set)
IEEE Network Types
B) ESS (extended service set)
In an ESS, a wireless client can associate with one AP while it is physically located near that AP. If the client later moves to a different location, it can associate with a different nearby AP. The standards also define a method to allow the client to roam or to be passed from one AP to another as its location changes

16. IEEE Network Types
B) ESS (extended service set)

17. Access Point Operation

18. Access Point Operation
An AP’s primary function is to bridge wireless data from the air to a normal wired network
An AP can also act as a bridge to form a single wireless link from one LAN to another over a long distance. In that case, an AP is needed on each end of the wireless link. AP-to-AP or line-of-sight links are commonly used for connectivity between buildings or between
cities

19. Point to Point

20. Access Point Operation
APs act as the central point of access

21. Access Point Operation
Any client attempting to use the WLAN must first establish an association with an AP
The AP can allow open access so that any client can associate, or it can
tighten control by requiring authentication credentials or other criteria before allowing associations
The AP can control many aspects of its WLAN by requiring conditions to be met before clients can associate. For example, the AP can require that clients support specific data rates, specific security measures, and specific credentials during client association and …

22. Access Point Operation
You can think of an AP as a translational bridge, where frames from two dissimilar media are translated and then bridged at Layer 2

23. Access Point Operation
For example :
the AP is in charge of mapping a VLAN to an SSID.

24. Access Point Operation
For example :
the AP is in charge of mapping a VLAN to an SSID.

25. Wireless LAN Cells
An AP can provide WLAN connectivity to only the clients within its range
The signal range is roughly defined by the AP’s antenna pattern. In an open-air setting, this might be a circular shape surrounding an omnidirectional antenna. At least the pattern will appear as a circle on a floor plan

26. Wireless LAN Cells An AP’s coverage area is called a cell
Clients within that cell can associate with the AP and use the wireless LAN
This concept is shown in Figure. One client is located outside the cell because it is beyond the AP’s signal range

27. Wireless LAN Cells
keep in mind that the pattern is three-dimensional, also affecting floors above and below, in a multilevel building

28. Wireless LAN Cells
The AP’s location must be carefully planned so that its range matches up with the coverage area that is needed

29. Wireless LAN Cells
Good
Bad

30. Wireless LAN Cells
Good
Bad

31. Wireless LAN Cells
Good
Bad

32. Wireless LAN Cells
Good
Bad

33. Wireless LAN Cells
The best approach to designing an AP’s location and range or coverage area is to perform a site survey

34. Wireless LAN Cells
The best approach to designing an AP’s location and range or coverage area is to perform a site survey
A test AP is placed in a desirable spot while a test client moves about, taking live measurements of the signal strength and quality. The idea is to plot the AP’s range using the actual environment into which it will be placed, with the actual obstacles that might interfere with the client’s operation.

35. Wireless LAN Coverage Area
Suppose that a typical indoor AP cell has a radius of 100 feet covering several rooms or part of a hallway. Clients can move around within that cell area and use the WLAN from any location. However, that one cell is rather limiting because clients might need to operate in other surrounding rooms or on other floors without losing their connectivity.

36. Wireless LAN Coverage Area
To expand the overall WLAN coverage area, other cells can be placed in surrounding areas simply by distributing other APs throughout the area

37. Wireless LAN Coverage Area
The idea is to place the APs so that their cells cover every area where a client is likely to be located. In fact, their cell areas should overlap each other by a small percentage, as shown in Figure

38. Wireless Roaming
When a client associates with one AP, it can freely move about. As the client moves from one AP’s cell into another, the client’s association is also passed from one AP to another.

39. Moving from one AP to another is called roaming
Wireless Roaming
Moving from one AP to another is called roaming

40. Wireless Roaming
When a client moves from one AP to another, its association must be established with the new AP. As well, any data that the client was sending just prior to the roaming condition is also relayed from the old AP to the new AP. In this way, any client connects to the WLAN through only one AP at a time. This also minimizes the chance that any data being sent or received while roaming is lost

41. Wireless Roaming
If the client maintains its same IP address as it roams between APs, it undergoes Layer 2 roaming.
If the client roams between APs located in different IP subnets, it undergoes
Layer 3 roaming

42. WLAN Architecture Traditional WLAN Architecture
Traditional WLAN architecture centers around the wireless access point. Each AP serves as the central hub of its own BSS, where clients located with the AP cell gain an association. The traffic to and from each client has to pass through the AP to reach any other part of the network.

43. WLAN Architecture Traditional WLAN Architecture
Notice that even though an AP is centrally positioned to support its clients, it is quite isolated and self-sufficient. Each AP must be configured individually, although many APs
might be configured with identical network policies. Each AP also operates independently.
the AP handles its own use of radio frequency (RF) channels, clients associate with
the AP directly, the AP enforces any security policies unassisted, and so on

44. Cisco calls this an autonomous mode AP
WLAN Architecture
Traditional WLAN Architecture
Cisco calls this an autonomous mode AP

45. WLAN Architecture Traditional WLAN Architecture
Because each AP is autonomous, managing security over the wireless network can be difficult. Each autonomous AP handles its own security policies, with no central point of entry between the wireless and wired networks. That means no convenient place exists for monitoring traffic for things like intrusion detection and prevention, quality of service, bandwidth policing, and so on

46. WLAN Architecture
Traditional WLAN Architecture

47. WLAN Architecture Traditional WLAN Architecture
In the figure, SSID A and SSID B are offered on two APs. The two SSIDs correspond to VLAN A and VLAN B, respectively. The APs must be connected to a common switched network that extends VLANs A and B at Layer 2. This is done by carrying VLANs A and B over an 802.1Q trunk link to each AP. Because SSIDs and their VLANs must be extended at Layer 2, you should consider how they are extended throughout the switched network. In Figure 15-7, SSID A and VLAN A have been shaded everywhere they appear. Naturally, they form a contiguous path that appears on both APs so that wireless clients can use SSID A in either location or while roaming between the two

48. WLAN Architecture Traditional WLAN Architecture
In the figure, SSID A and SSID B are offered on two APs. The two SSIDs correspond to VLAN A and VLAN B, respectively. The APs must be connected to a common switched network that extends VLANs A and B at Layer 2. This is done by carrying VLANs A and B over an 802.1Q trunk link to each AP. Because SSIDs and their VLANs must be extended at Layer 2, you should consider how they are extended throughout the switched network. In Figure 15-7, SSID A and VLAN A have been shaded everywhere they appear. Naturally, they form a contiguous path that appears on both APs so that wireless clients can use SSID A in either location or while roaming between the two

49. WLAN Architecture Traditional WLAN Architecture
This concept becomes important when you think about extending SSIDs to many APs over a larger network

50. WLAN Architecture Cisco Unified Wireless Network Architecture
Cisco has collected a complete set of functions that are integral to wireless LANs and called them the Cisco Unified Wireless Network
This new architecture offers the following capabilities, which are centralized so that they affect wireless LAN devices located anywhere in the network:
■ WLAN security
■ WLAN deployment
■ WLAN management
■ WLAN control

51. WLAN Architecture
Cisco UWNA Vs Legacy Model

52. WLAN Architecture Cisco Unified Wireless Network Architecture
In the Cisco unified wireless network, a lightweight access point (LAP) performs only the real-time operation.

53. WLAN Architecture Cisco Unified Wireless Network Architecture
The management functions are all performed on a wireless LAN controller (WLC)

54. WLAN Architecture
Cisco Unified Wireless Network Architecture

55. WLAN Architecture
Cisco Unified Wireless Network Architecture