Shahab Ali, Author at Networkustad

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Wireless Access Points (APs)

In the LAN (Wired Network) each client connects to a switch. The switch is the centre point for each client to gain access to the network. The wireless Access Points also connects to the switch. Wireless clients discover nearby APs using their wireless NIC. The wireless Access Points are advertising their SSID for the client. Clients select wireless Access Points and attempt to connect using authentication. After being authenticated, wireless users can access network resources. The wireless Access Points has two types: autonomous APs and controller-based APs.

Autonomous APs

Autonomous APs are useful in situations where only a couple of APs are required in the network. We can configure autonomous APs using the Cisco CLI or a GUI. We can control multiple APs using wireless domain services (WDS) and managed using Cisco Works Wireless LAN Solution Engine (WLSE). The home router is an example of an autonomous AP. In the case of increased wireless demands, more APs would be required. Each AP has its network and operates independently from other APs. The APs can be independently configured. The figure below illustrates the Autonomous APs.

Controller-Based APs

It is server-dependent APs that not need any initial configuration. Controller-based APs are helpful where many APs are required in the network. When new AP is added to the network, the controller automatically configures and manage the APs. The benefit of the controller is that it can be used to manage many APs. The figure below illustrates the controller-based APs.

Wireless Access Points (APs) 2

Wireless Home Router

A Wireless home router is a device that communicates between the internet and the devices in your home that connects to the internet. It routes traffic between the devices and the internet. The selection of the right kind of router for your home is very important. A wireless home router usually serves as:

Access point– It usually provides connectivity for 802.11a/b/g/n/ac wireless access
Switch– A Wireless home router also contains four full-duplex switch-port with the speed of 10/100/1000 to connect wired devices
Router– The router server as the default gateway for connecting to other network infrastructures

Wireless router server as a small business or residential wireless access device. It is connected to the Internet Server Provider modem and share internet services using RF signals. Internal devices wirelessly determine the router by its SSID and attempt to connect and authenticate with it to access the Internet. The SSID is the abbreviation of Service Set Identifier. The figure below illustrates the working of the wireless home router.

Most wireless routers provide advanced features, for example, high-speed access, video streaming, IPv6 addressing, QoS, configuration utilities, and USB ports to connect printers or portable drives. The quality we should consider for choosing a good router is as under:

Wi-Fi coverage

Wi-Fi signal availability mostly depends on the size of the home and the barriers that prevent signals from reaching their destinations. So look for a router that has the potential to reach the far-off corners of the home.

Wi-Fi performance

Router technology has changed time to time, so selects the latest technology and has updated firmware. The multi-user, multiple-input, multiple-output (MU-MIMO) technology is the latest technology. The MU-MIMO allows WI-FI router to communicate with multiple devices simultaneously.

Wi-Fi security

Wi-Fi security is an important aspect. Cybercriminals can enter to your home network and can copy your data; they can also install malware and viruses in your devices. They can also get your personal and financial information. So having a router providing network-level protection can help protect against cyber-attacks at the port of entry.

Wireless Network Interface Card (WNIC)

To communicate without wire, computers and end devices require a wireless network interface card (WNIC). A wireless network interface card (WNIC) is a network card which connects to a wireless radio-based network. It is just like other NICs, functioning on the Layer 1 and Layer 2 of the OSI Model. It performs the same operation as a normal network card, except instead of operating through network cables, it operates wirelessly. The card contains an antenna to send and receive microwave signals.

Laptops, tablets, smartphones now all include built-in wireless NICs. However, if a device does not have a built-in wireless NIC, then we can use a USB wireless adapter.

If we need a wireless network interface card (WNIC) in a desktop computer, we can install the WNIC in the PCI bus. The card is also available in the shape of USB and PC card. The figure below illustrates both USB WNIC and WNIC for PC’s expansion slot.

Comparison Between WLAN and LAN

A WLAN allows devices to connect and communicate without using wires or cables. But in the traditional wired LAN devices communicate over Ethernet cables. Both WLAN and LAN share a similar origin. The IEEE has chosen the 802 network standards for LAN/MAN portfolios of computer network architecture. The two main 802 standards are 802.3 Ethernet and 802.11 WLAN. Though, there are significant differences between both. Wireless LANs use Radio Frequencies instead of cables at the physical layer and MAC sublayer of the data link layer. The main differences between WLAN and LAN are as under:

The first difference between both is that 802.13 uses Ethernet cable but 802.11 uses RF waves. The RF allows data frames travelling without wire and available to anyone who can receive the RF signal.
RF is insecure from outside signals, but the cable is in an insulating sheath. Radios working alone in the same geographic area, but using the same or a similar RF can interfere with each other. The signal varies as it reflects, refracts and lost depending on the environment.
In the WLAN when the RF signal travels further away from the source, radio stations could start playing over each other and static noise increases. Finally, the signal is lost. But LANs have cables with appropriate length to maintain signal strength.
Wireless LAN is more susceptible to attacks because it is more exciting. But in the LAN, attacks depend on whom and what was installed into devices as well as what is being connected.
The use of Wireless LANs is a question to additional regulations and sets of standards that are not applied to wire LANs.
Wireless APs and wireless Routers have a limit of several users connected to a single Wireless Router depending on the type of Wireless Router. But LAN depends on the number of Ethernet ports that a router or a switch has. We can increase the number of port adding additional switches.
WLAN 802.11 advised collision-avoidance (CSMA/CA) instead of collision-detection (CSMA/CD) for media access to dynamically avoid collisions within the media.
The frame format of WLANs is different than wired Ethernet LANs. So, WLANs require additional information in the Layer 2 header of the frame.
WLANs increase privacy issues because radio frequencies can reach anyone outside the required location.

IEEE 802.11 Standards

The IEEE 802.11 WLAN represents the IEEE designation for wireless networking. IEEE 802.11 standard defines how RF in the unlicensed ISM frequency bands is used for the physical layer and the MAC sub-layer of wireless links. Several implementations of the IEEE 802.11 standard has defined by IEEE over the years. All the standards use the Ethernet protocol and the CSMA/CA access method. The highlights of these standards are:

802.11– 802.11 was released in 1997. This is the original WLAN standard. The operating frequency of that standard is 2.4 GHz band. The speeds of this standard are up to 2 Mbps. This standard is now obsolete. When 802.11 standards were providing 2 Mbps speed, at the same time wired LANs was operating at 10 Mbps speed.
IEEE 802.11a– 802.11a was released in 1999. The speed of this standard is 54 Mbps and the operating frequency is 5GHz. It is incompatible with the 802.11b and 802.11g wireless standards. Due to high frequency, the coverage area of this standard is smaller and the devices contain one antenna for transmission and reception of signals.
IEEE 802.11b– The standard was released in 1999. Operating frequency of this standard is 2.4 GHz and offering speed is up to 11 11Mbps. The range of devices with 802.11b standard is long-range than 802.11a because the operating frequency is lower than 802.11a. The devices can better penetrate building structures than devices based on 802.11a standard. Wireless devices contain a single antenna to transmit and receive signals.
IEEE 802.11g– 802.11is a popular wireless standard today is the successor of 802.11b. It was released in 2003. The operating frequency is 2.4 GHz band; the standard offers speeds of up to 54 Mbps. The frequency band is the same as 802.11b but with better speed than 802.11b. The devices have one antenna to transmit and receive wireless signals. It is also compatible with 802.11b. The speed of the device is reduced when supporting an 802.11b client.
IEEE 802.11n– This is the first standard specify MIMO, was released in 2009. The standard allows operating with two frequencies – 2.4 GHz and 5 GHz and is referred to as a dual-band device. The data rates range is between 150 Mbps to 600 Mbps covering the distance range of up to 70 m. APs and wireless client using 802.11g required multiple antennas for multiple-in multiple-out (MIMO) technology. MIMO required multiple antennas for both the transmitter and receiver. Up to four antennas can be used with 802.11n devices. The standard is also is backwards compatible with 802.11a/b/g devices.
IEEE 802.11ac– Current home wireless routers are likely 802.1ac-compliant, and operate in the 5 GHz frequency space was released in 2013, providing data rates ranging from 450 Mbps to 1.3 1300 Mbps. It also uses MIMO technology to get better communication performance. The standard can support up to eight antennas. The standard is backwards compatible with 802.11a/n devices but it limits the expected data rates.
IEEE 802.11ad – The standard is expected to be approved in November 2019. It is also known as “WiGig”, uses tri-band: 2.4 GHz, 5 GHz, and 60 GHz, and offers theoretical speeds of up to 7 Gbps. However, this speed can achieve only if the client device is situated within 3.3 meters or 11 feet of the access point. Because 7 Gbps speed is possible on 60 GHz which required line-of-site, therefore, it cannot penetrate through walls. It switches to 2.4 GHz and 5 GHz bands for backward compatibility with existing Wi-Fi devices. The compatibility environment limits the expected data rates.
The table below illustrates the comparison between all IEEE 802.11 standards including the backwards compatibility.

Radio Frequencies

Radio frequencies refer to the rate of oscillation of electromagnetic radio waves in the range of 3 kHz to 300 GHz. This band is used for communications transmission and broadcasting. Different radio frequencies are useful for different wireless technologies. For example, some frequencies are used to fore radio broadcasting; some frequencies are used for television broadcasting.

The use of radio waves is in many different types of communication which are defined in the electromagnetic spectrum. The electromagnetic spectrum contains all the frequencies of electromagnetic waves including visible light waves, microwaves, and radio waves. The radio wave spectrum is included in the electromagnetic waves spectrum having the frequency range between 3 kHz and 300 GHz.

The radio frequency spectrum is divided into different ranges called radio frequency bands for a huge number of applications including AM Radio, FM radio, television, cellular networks, Bluetooth, walkie-talkies, satellite communications, military applications, and much more. All wireless devices operate in the radio frequencies range of the electromagnetic spectrum.

The radiofrequency allocation from the spectrum is the responsibility of the International Telecommunication Union – Radiocommunication Sector (ITU-R). The radio frequency bands are allocated for different purposes. Some bands in the electromagnetic spectrum are used for applications, such as air traffic control and emergency responder communications networks. Some bands are free of license, for example, the Industrial, Scientific, and Medical band (ISM) and the unlicensed national information infrastructure (UNII) band.

The frequency range for wireless communication is 3 Hz to 300 GHz. The WLANs, Bluetooth, cellular, and satellite communication all operate in the microwave UHF, SHF, and EHF ranges. The WLAN frequency is 2.4GHz ISM bands and 5 GHz UNII bands. Specifically, the following frequency bands are allocated to 802.11 wireless LANs:

4 GHz (UHF)- 802.11b/g/n/ad
5 GHz (SHF)- 802.11a/n/ac/ad
60 GHz(EHF) – 802.11ad

The components of the electromagnetic spectrum are gamma-rays, x-rays, ultra-violet, visible light, infra-red, microwaves and radio-waves. We will discuss the radio-waves in detail. Radio wave has the longest wavelengths, from a few centimetres to thousands of meters. The figure below illustrates the radio frequency band.

Wireless Technologies

Wireless technologies refers to technology that makes possible to communicate over a distance without using wires or any other conductors. We can use wireless technology for both long and short distance. Wireless technologies network has based on electromagnetic waves like radio frequencies (RF), infrared (IR), satellite, etc. We can broadly classify wireless technologies as:

Wireless Personal-Area Networks (WPAN)– This type of wireless operates in the range of a few feet. The Bluetooth and Wi-Fi Direct-enabled devices are used in Wireless Personal-Area Networks (WPAN).
Wireless LANs (WLANs)– The WLAN devices can communicate in the range of a few hundred feet such as in a room, home, office, and in the campus.
Wireless Wide-Area Networks (WWANs)– The WWAN devices can communicate as long-range such as a metropolitan area network, cellular network, and between intercity links through microwave relays.

The above classes of wireless technologies use different types of standards. Following is the short introduction about the various wireless technologies available to connect devices to these wireless technologies networks:

Bluetooth– Bluetooth is the original IEEE 802.15 WPAN standard. It uses a device-pairing process to communicate. Bluetooth can communicate for short distance up to 100m.
Wi-Fi (wireless fidelity)– This is an IEEE 802.11 WLAN standard providing network access to home and corporate users. It can send and receive data, voice and video up to the distance of 300m.
WiMAX (Worldwide Interoperability for Microwave Access)– An IEEE 802.16 WWAN define the WiMAX standards. It provides wireless broadband access for the distance up to 50 km. It is the alternative of cable and DSL broadband connections. WiMAX also provides cellular broadband services since 2005.
Cellular broadband– Cellular broadband includes different corporate, national, and international organizations providing cellular access to mobile broadband network connectivity. In 1991 the 2nd generation (2G) cell phones were introduced under cellular network. In 2001 third-generation (3G) and then in 2006 fourth-generation (4G) cellular technology was introduced with higher speed. Currently, the world is moving towards the fifth-generation (5G) cellular network. The 5G network is supposed to change your life with its revolutionary speed. The speed of 5G is measured in bytes instead of bits. The 5G peak download speed is 2.5 GB/s , or 2,560 MB/s. The 5G peak upload speed is 1.25 GB/s, or 1,280 MB/s
Satellite broadband– This is very important for network access to remote sites using the directional satellite dish that is aligned with a specific geostationary Earth orbit (GEO) satellite. Satellite broadband is a more expensive system. It is an option for those who live in rural areas where conventional fixed-line based broadband services like DSL are not available. The speed of satellite broadband is lower than in conventional broadband lines.

Introduction to Wireless

Wireless Communication is the fastest growing and most vibrant technological areas in the communication field. It can provide client mobility, the skill to connect from any location and at any time, and the skill to roam while staying connected. It is the technique of transmitting information from one point to other, without using any connection like wires, cables or any physical medium.

A WLAN is a category of wireless network commonly used in homes, offices, and campus environments. WLAN uses radio frequencies instead of cables; it is usually applied in a switched network. The frame format of the WLAN is similar to Ethernet. In the WLAN the transmitter transmits data and the receiver receives data within few meters

e.g. T.V. Remote Control and to thousand kilometres e.g. Satellite Communication. The current business wireless environments need connectivity to the networks while people are on the move. The current network support connectivity during the move and the people can use multiple devices such as laptops, tablets, and smartphones. There different type of architecture that makes this possible. The most important as of business point of view is the wireless LAN (WLAN).

Benefits of Wireless

It has many benefits for both in the business environment and at-home environment. The important benefits are the following:

Increased efficiency

Wireless network improves data communications between businesses network, partners and customers.

Access and availability

A wireless network allows users to communicate during the move, for example, a cell phone. We haven’t needed any cables or adaptors to access the network.

Flexibility

The wireless network provides services to workers without sitting at dedicated computers. They can carry on productive work while away from the office. This is the modern style of working, the worker can work directly from home.

Cost savings

Wireless networks also a cost-saving option for corporate and home users. It is an easy and cheaper way of networking, especially in the buildings or where the property owner does not permit the installation of cables.

EtherChannel Configuration

EtherChannel Configuration in the networking has a set of restrictions that state what you can do and what you cannot do. Before configure and establish the EtherChannel, it is important to know the restrictions. Here are some basic restrictions and guidelines on setting up EtherChannel:

EtherChannel support– Ethernet channel support on all interfaces must support with no requirement that interfaces be physically adjacent, or on the same module.
Speed and duplex– For EtherChannel configuration, all interfaces which joining the Channel must be operated with the same speed and duplex settings.
VLAN match– All interfaces in one EtherChannel bundle must be the member of the same VLAN, or be configured as a trunk.
Range of VLAN– An EtherChannel supports the same allowed range of VLANs on all the interfaces in a trunking EtherChannel. If the allowed range of VLANs is not the same, the interfaces do not form an EtherChannel, even when set to auto or desirable
Maximum Ports in Channel Group – We can assign up to eight ports to a channel group. Using LACP, we can configure 16 ports in the port group, eight ports can be active and the other eight ports are in Standby mode. This configuration is very useful when the active group is loose, the standby links will activate immediately.
EtherChannel between Different Switches – PAgP is a Cisco propriety protocol, and LACP is an open standard protocol. If we need to create EtherChannel with switches from other vendors, we will configure EtherChannel using LACP.
EtherChannel Connection Modes – EtherChannel uses two types of Protocols LACP and PAgP. LACP also has two configuration modes, Active and Passive. The PAgP is also two modes Auto and Desirable. LACP Active link attempts to start LACP session by sending out LACP negotiation packets and Passive link only respond to packets that it receives. Passive mode never starts a negotiation. As with Active link in LACP, Auto links in PAgP start negotiation, the PAgP Desirable is the same to LACP Passive links waiting for PAgP negotiation packet.

Configuring Interfaces

EtherChannel configuration using LACO protocol has two different steps :

Select and identify the interfaces that will create the EtherChannel group. Then enter the“interface range interface_range” command in global configuration mode. Using the “range” keyword allows you to select multiple interfaces and configure them all at once.
The command syntax for creating a channel group is “channel-group identifier mode active command in interface range configuration mode. The identifier identifies a channel-group number. The mode can be active/passive/on The keywords active/ passive identify that this as an LACP EtherChannel.

By default, EtherChannel is disabled on Cisco switches. For EtherChannel verification, there are several commands we can use. The first command we can use to verify the EtherChannel is “show interface port-channel” command. The output of this command displays the general status of the port channel interface.

When several port-channel interfaces are configured on the same device, use the show EtherChannel summary command to simply display one line of information per port channel. In Figure 2, the switch has one EtherChannel configured; group 1 uses LACP. The figure below illustrates the output of this command.

We can use the show “etherchannel port-channel” command display full information about a particular port channel interface, The figure below illustrates the output of this command.

EtherChannel Configuration 4

We can display role information about any physical interface which is a member of an EtherChannel bundle using the “show interfaces etherchannel” command.

EtherChannel Protocols- PAgP and LACP

EtherChannel is used to bundle physical links into a single logical link. We can bundle maximum of 8 physical links into one logical link. When physical links bundled into a single logical link, the STP only sees a single logical link and is not able to block anything. There are two types of the protocol used for EtherChannel, PAgP and LACP. EtherChannel protocols remove any loops within the physical links.

The Etherchannel protocols also maintain a record of each physical link. In case of any physical link failure or restoration, the protocols manage the deletion and addition of the link without informing the STP about the change. Cisco switch uses the IEEE standard Link Aggregation Control Protocol (LACP) and Cisco proprietary PAgP. Each EtherChannel is called a channel group. We can add a physical port into the group using the “channel-group group-number mode on” command in the interface configuration mode. We can also create and configure the EtherChannel without the use of PAgP or LACP. This type of EtherChannel is called a static or Unconditional EtherChannel.

PAgP

Port Aggregation Protocol is a Cisco-proprietary protocol that can only work on Cisco switches or on switches licensed by vendors to support Port Aggregation Protocol. The protocol helps the automatic creation of Etherchannel using the exchange of PAGP packets. Port Aggregation Protocol packets are exchanged between EtherChannel-capable ports to negotiate the establishment of a channel. Port Aggregation Protocol also checks for configuration stability and manages link additions and failures between two switches. It ensures that when an EtherChannel is created, all ports have the same type of configuration.

PAGP packets contain all the information of the neighbour switch. The receiving switch learns the neighbour switch identity capability of supporting PAGP and then dynamically groups similarly configured ports into a single logical link. When PAgP is enabled, the PAgP packets are sent after every 30 seconds. The Port-Aggregation Protocol (PAgP) uses the layer 2 multicast address 01-00-0C-CC-CC-CC.

For establishing EtherChannel, all ports must have the same data speed, duplex setting, and VLAN information. Any modification on the port configuration can cause changes on all other ports of the channel. The figure shows the modes for Port Aggregation Protocol.

PAgP

On– Interfaces configured with this mode do not exchange PAgP packets. On mode force the interface to channel without PAgP or LACP. Port with “on” mode, will be created EtherChannel only when another interface group in EtherChannel “on” mode.
PAgP desirable– Interface with PAgP desirable mode remain in an active negotiating state in which the interface initiates negotiations with other interfaces by sending PAgP packets after every 30 seconds.
PAgP auto– Interface with PAgP auto mode places the interface in a passive negotiating state in which the interface reply to the PAgP packets received, but does not initiate any Port Aggregation Protocolnegotiation.

For establishing EtherChannel the modes compatibility on both side is important. For example, if one side is configured to be in auto mode, waiting for the other side to initiate the EtherChannel negotiation. If the other side is also set to auto, the PAgP packet will never exchange and the EtherChannel does not form. If all modes are disabled, or if no mode is configured, then the EtherChannel is disabled. The figure below illustrates the mode of the Port Aggregation Protocol for EtherChannel establishment.

The on mode manually set the interface in an EtherChannel, without any negotiation. If one side is set to on the other side must be set to for establishing EtherChannel. If the other side is set to negotiate parameters through Port Aggregation Protocol, the EtherChannel is not possible, because the side that is set to on mode does not negotiate. The Etherchannel configuration for the above topology is as under:

Note:- PAgP Modes are: On, Desirable, Auto

Switch1

Switch1(config)#interface range e0/0-3
Switch1(config-if-range)#channel-group 1 mode auto
Switch1(config-if-range)#interface port-channel 1
Switch1(config-if)#switchport mode trunk

Switch2

Switch2(config)#interface range e0/0-3
Switch2(config-if-range)#channel-group 1 mode desirable
Switch2(config-if-range)#interface port-channel 1
Switch2(config-if)#switchport mode trunk

The Port Aggregation Protocol does a configuration check on participating interfaces and confirms that the neighbouring interfaces are also using Port Aggregation Protocol. In the Port Aggregation Protocol interfaces that don’t have similar configurations will not participate, and we won’t get an accidental switching loop.

LACP

LACP is an open protocol, published by IEEE under the 802.3ad specification. The IEEE also release a new definition of the LACP in IEEE 802.1AX standard for local and metropolitan area networks. LACP, similarly allows several physical ports to be bundled to establish a single logical channel. It allows a switch to negotiate an automatic bundle using the LACP packets. The function of the LACP is similar to PAgP with Cisco EtherChannel. The difference is that LACP is an IEEE standard and PAgP is Cisco Propiaritry. The LACP is used to establish EtherChannels in multivendor environments. On Cisco devices, we can use both protocols. The LACP uses multicast address 01-80-c2-00-00-02.

LACP is the same in the functioning and proved the same negotiation benefits as PAgP. It helps establish the EtherChannel link by detecting the configuration of each side and check the compatibility. The figure shows the different modes for LACP.

LACP

On– similarly the on mode ensure the interface to channel without LACP. Interfaces with this mode do not exchange LACP packets.
LACP active– The active mode places a port in an active negotiating state. The port starts negotiations with other ports by sending LACP packets.
LACP passive– The passive mode places a port in a passive negotiating state. In the passive mode, the port responds to the LACP packets that it receives, however the passive port does not initiate LACP packet negotiation.

Similar to PAgP, modes must be compatible on both sides for establishing EtherChannel. The on mode is repeated because it creates the unconditional EtherChannel configuration without PAgP or LACP dynamic negotiation. The simple configuration of LACP for the above topology is as under:

Note:- LACP Modes are: On, Active, Passive

Switch1

Switch1(config)#interface range e0/0-1
Switch1(config-if-range)#channel-group 1 mode active
Switch1(config-if-range)#interface port-channel 1
Switch1(config-if)#switchport mode trunk

Switch2

Switch2(config)#interface range e0/0-1
Switch2(config-if-range)#channel-group 1 mode passive
Switch2(config-if-range)#interface port-channel 1
Switch2(config-if)#switchport mode trunk

The configuration of LACP is almost same to PAgP configuration. The difference is only the use of the keyword. The keywords used by LACP is active and passive. The active keyword shows that the interface uses LACP protocol. The passive keyword indicates the use of LACP, however, it can only respond to requests but cannot send any LACP packet.