Network wireless switch: networking – Why are there no wireless switches?

networking – Why are there no wireless switches?

Modern MU-MIMO (Multi-user MIMO) access points are the closest we have to switched Wi-Fi.

Detail

There are two main features we associate with ethernet switches.

1. Non broadcast packets are sent only to the nominated user device.
2. The switch fabric overall has a higher bandwidth than any individual link.

Until recently, Wi-Fi access points could do neither of these things, but with modern beamforming techniques they can do both.

An analogy

We normally think of radio as being like standing in the middle of a field shouting. As long as only one person is shouting, everyone else in the field can hear them clearly, but if more than one person is shouting at once it starts to get garbled, so we take it in turns (Time-division multiplexing). It is a shared medium.

Beamforming is more like speaking into a parabolic dish pointed at someone else’s ear. Because the signal is directed at a specific location, there is no need to shout, and it is almost inaudible for everyone else. Not only this but many pairs of people in the field can do the same, with none of their conversations interfering with each other.

This, this beamforming technique fulfils both of our criteria for ‘wireless switching’.

MIMO

The practical implementation of these techniques in WiFi is MU-MIMO.

In radio, multiple-input and multiple-output, or MIMO (/ˈmaɪmoʊ, ˈmiːmoʊ/), is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation.

Effectively, if you have multiple antennae, so each signal takes a slightly different path from access point to user device, MIMO can potentially use much of the the bandwidth of each ‘stream’ simultaneously (like pointing one parabolic dish at your left ear and another at your right *8′).

MU-MIMO is an enhancement to MIMO which allows access points to maintain connections to multiple user devices simultaneously.

Multi-user MIMO (MU-MIMO) can leverage multiple users as spatially distributed transmission resources, at the cost of somewhat more expensive signal processing.

Without MU-MIMO, access points connect to only one user device at a time, so access to different user devices has to be spread out over time. With MU-MIMO that limitation doesn’t apply.

Wi-Fi 5 (802.11ac) supported MU-MIMO in the Downlink direction – so multiple user devices could receive packets simultaneously, but would have to wait their turn to acknowledge receipt of those packets. This functionality was only optionally supported on devices with “Wave 2” certification.

Wi-Fi 6 (802.11ax) supports MU-MIMO in both the Downlink and Uplink directions. With multiple bi-directional spacial streams, equivalent to separate Cat5 cables coming from an Ethernet switch, this is the closest Wi-Fi currently gets to switched ethernet.

MU-MIMO in practice

MU-MIMO technology is not very widely supported yet, and all devices (access point and user devices) have to support it for it to be used.

Just one device within rance of the access point which doesn’t support MU-MIMO will prevent all MU-MIMO devices from making use of their MU-MIMO capability for the duration of it’s transmissions.

What is a Wireless Network Switch? Does It Exist?

PAGE CONTENT:

What Is a Wireless Network Switch?

Why Are There No Wireless Switches?

Have you ever wondered if a wireless network switch exists? The advancement in networking technology in recent years has made many people consider the possibilities of going beyond traditional networking via switches and routers.

In this article, you will learn what wireless network switches are if they exist and how it is expected to function if such exist.

What Is a Wireless Network Switch?

From the knowledge of a regular network switch, the wireless network switch can be considered a device connecting various IT devices (such as servers, routers, other controllers, printers, and PCs) within a single Local Area Network without the physical input/ output ports or RJ45 cables.

This technology differs from the usual network switch because it uses the wireless network to achieve the same purpose as a regular network switch. In addition, unlike the traditional network switches, there is no limitation to the number of ports connected to them.

Hence, it has many advantages over its traditional counterpart, making it reliable and budget-friendly, especially in an enterprise setting. Information and resource sharing is seamless, using each device’s MAC addresses.

Why Are There No Wireless Switches?

Despite the technological advancement and level of civilization in the world today, there are presently no wireless network switches. There are many reasons this technology is still in the development pipeline. Let’s take a look at some of those reasons:

1. The functions of a network switch are enormous, and forcing all of that functionality (without the regular fiber cables and input/ output ports) into a virtual overlay requires in-depth research, resource, and technicality.
2. Wireless network switches must beat the fiber optics speed to gain significant relevance. At the moment, fiber optic still offers one of the best connectivity. Some network switches use fiber optic connectivity to send data packets from one device to another in the same network.
3. Other dependent technologies will become extinct with a wireless network switch in vogue. Different network types (Ethernet, RapidIO, ITU-T G.hn, 802.11, ATM, Fibre Channel) that could be connected in a single network will become almost impossible.
4. Security attacks may also increase because everything is connected to one network. An entry into any device is a total compromise on the whole system.
5. Other operational benefits like network intrusion detection, firewall, and performance analysis modules with the regular network switch will be suspended or added later as an update to the technology.

Final Words

In conclusion, whether wireless network switches exist or not, there is no harm in speculating what this technology will look like. This article has helped bridge the gap between the traditional and the wireless network switch. Now, you are confident about what a wireless network switch is and why they do not exist at the moment.

Wireless network infrastructures | Network Solutions/LAN Magazine

WLAN switches are now a new type of device for use in large enterprise wireless LANs. These infrastructure components concentrate access from the wireless network to the local area network. In doing so, they offer management and security features for access points. The article discusses various technical approaches and WLAN switching architectures.

Up until the last year, the development of wireless LANs was limited by an “arms race” in the development of access points. Manufacturers have responded to criticism regarding security and management by implementing even more relevant features, often coupled with an intelligent control chip to optimize wireless traffic performance. With the advent of access points operating in two and three bands (802.11b, a and g), their further growth is even more dramatic. However, the structural weaknesses of access point-based infrastructure cannot be addressed by better equipping them, as the key problems that enterprises have to face in their wireless installations cannot be solved in this way. Clearly, a new infrastructure layer needs to be introduced and tasks such as security and management combined at a central site, preferably a switch.

In most WLAN switching solutions, the intelligence for resource-intensive encryption and authentication methods (DES, TKIP, AES, and respectively EAP/TLS, 802.1x, and RADIUS) has actually been moved to this central site. In the extreme case, an external access point can be reduced to a “bare” radio, and its basic functions are reduced to bridge functions. As a result, very cheap access points can be created. When using them, the network designer no longer has to consider every last detail, at least in terms of cost, since expanding the network by installing additional access points turns out to be very cheap.

Traditional WLAN players Nortel Networks, Proxim and Symbol Technologies have to contend with newcomers whose first products were wireless switches. These include Airflow, Airspace, Aruba Wireless Network, Legra, Trapeze Networks and Vivato. Earlier this year, Extreme Networks also introduced a wireless switch, and Hewlett-Packard announced its intention to enter the WLAN switching market. So far, 3Com and Cisco have not announced any official plans. Experts expect that in the near future Cisco will offer one of the start-up manufacturers to go under its wing, and the industry leader will not surprise the general public with his own solution. Among the newcomers – everyone is like one from the USA, only Trapeze made an attempt to enter the European market: in July, the company, many of whose employees previously worked at Extreme, had a distributor and intermediary in Germany. Aruba has moved its German market entry to the end of the year (originally scheduled for early summer), with a European debut in England and France expected in the fall at Networld + Interop in Paris (see Figure 1).

The rest will have to wait until the beginning of next year, as well as intending to settle in the new market segment of Chantry Networks, whose Beacon MasterSwitch is more of an IP router from a technological point of view. However, its functionality is largely the same as that of WLAN switches. There are several other products on the market that are not “true” switching solutions: Bluesocket’s Wireless Gateway 1100/2100 and Reefedge’s Connect System. Both concentrate the security and management functions of the wireless network on a server basis. Reefedge’s solution is further equipped with a “border controller” plugged directly in front of the access point, whose role is to apply centrally defined rules to access points.

A NEW KIND OF SWITCHES

Wireless LAN switches are “network devices that integrate 802. 11 wireless devices into an Ethernet switching infrastructure and centralize functions such as network management, security, mobility, and compliance.” So Gabriel Brown from the American analytical company Unstrung is trying to describe something for which there has not yet been a generally accepted definition. Looking at the functions of WLAN switches gives a differentiated picture. If a conventional Ethernet switch essentially distributes packets according to the Media Access Control (MAC) addresses of the respective ports and is responsible for high data rates, then the WLAN switch has to do a little more. Along with MAC addresses, it manages IP addresses, takes care of user accounting (security and management), and partially hosts a number of applications.

Security means that the switch performs various functions: encryption at the link layer, firewall and virtual private network (Virtual Private Network, VPN) support at the network layer, integration with the corporate authentication process, and much more. Moreover, the WLAN switch manages not one user per port (usually the number of 10/100 Mbps Ethernet ports reaches 20), but as many as are currently registered on the access points assigned to the switch. Thus, with a static average load of five users per access point, a 20-port switch manages the access rights of hundreds of users, including all rules associated with them. Connection to the corporate network is usually organized via Gigabit Ethernet.

If the LAN switch guarantees the user a certain bandwidth through a dedicated connection between ports, then the WLAN switch solves this problem at a higher level. It would be hardly possible to do this at the level of a single port, since there are no physically isolated interfaces in the air. In the case of WLAN switches, the air also remains a shared medium. However, in this case, bandwidth can be reserved and guaranteed through user administration or at the application level, regardless of where the user physically establishes a wireless connection to the network. The maximum wireless throughput (11 Mbps for 802.11b and 56 Mbps for 802.11a and g) of course determines the upper limit. In fact, WLAN switches are more like Layer 2-7 switches (if there are applications) and Layer 2-4 switches if they are not.

Switching nodes must be able to handle many tasks, and therefore they are equipped with many high-performance processors and application-specific integrated circuits (Applications Specific Integrated Circuit, ASIC). This makes it clear that WLAN switching capability is not achievable by simply “upgrading” a conventional Ethernet switch, and indeed it is a completely new class of devices (see Figure 2). This is the main argument, based on which newcomers to the WLAN market are going to compete with established switch vendors.

In almost all cases, WLAN switch manufacturers seek peaceful coexistence with existing LAN switches. The exception is Proxim. The manufacturer views its Maestro as full-fledged Layer 2 LAN switches that, among other things, can work with wireless networks. Accordingly, the company aims to replace existing Layer 2 switches. What advantages or disadvantages this approach brings for “WLAN switching” will be shown by the first tests. In any case, Proxim points to the benefits of integrating wired and wireless switching in the same chassis.

DIFFERENT ARCHITECTURES

Most manufacturers’ concept of WLAN switches is to be in cabinets from which cable runs to individual access points (usually on each floor). Each access point connects directly to a switch port (see Figure 3 ). Aruba and Chantry prefer another option where the data center/data center hosts something like a backbone WLAN switch (however, both companies also offer cabinet switches) (see Figure 4 ). There is no direct physical connection between access points and dedicated WLAN switch ports. It is carried out through the local network and conventional Ethernet switches. By the way, almost all switching solutions in wireless networks support the power supply of their access points over an Ethernet cable (Power over Ethernet, PoE). In the case of an indirect connection, this standardized power supply function must be supported by the intermediate LAN switch.

The centralized architecture is proposed to be used primarily in large enterprises with a common information technology department and a corresponding computer center. A centralized component is easier to control and less expensive than multiple distributed devices. On the other hand, the central WLAN switch must be much more powerful than the switch on the floor, and requires more costs. With a decentralized structure, it is much easier to respond flexibly to changes in bandwidth requirements. As for aspects such as scalability and availability, they should be approached much more critically in a centralized structure than in a distributed one. In the latter, if one WLAN switch fails, the rest will continue to work, while in a centralized structure, such an incident would mean disconnecting all wireless users from the network. Aruba offers a solution with a redundant WLAN backbone switch that will continue to process traffic in the event of a failure.

Both architectures are scalable: if more users and therefore more access points need to be served, or more bandwidth is required, then another WLAN switch is installed on the desired floor. And while additional switches can be placed in data centers, however, the requirement expressed in this way is not so easy to satisfy. In either case, you can implement nodes that support up to 1000 access points.

TOTAL FREEDOM OF MOVEMENT

No matter where the switches are physically located, they serve to provide mobility. 802.11 standards support link layer mobility so users can move between different access points transparently. IP, as a network layer protocol, does not have a corresponding standard mechanism to support mobility. This has led to WLAN installations that have been implemented so far centered on the access point being located on a single backbone subnet through which all access points of the enterprise were connected to each other. Given that in the case of large installations and network structures with a large number of subnets in a similar situation, the effectiveness of this approach decreases and the cost increases, wireless networks designed in this way will have scalability problems (at the latest after the implementation of the VPN): when passing through one firewall traffic from the subnet where all access points are located, the firewall can be a bottleneck.

All WLAN switching solutions consider mobility through the lens of layer 2 switch functionality. Bluesocket, Chantry and Reefedge use special network layer mechanisms: for example, Mobile IP is Reefedge’s own extension.

MANY SWITCHES, FEW APs

Figure 5. Symbol introduced its WLAN switches to the market last year, then under the Mobius name. Today’s WS 5000 series WLAN switches are identical to the Mobius series right down to the name.

The illusion of thinning access points in different WLAN switching solutions from different manufacturers is expressed in many ways. Bluesocket and Reefedge don’t play this game as they offer more than just their own hotspots. Perhaps the most radical approach to simplification of access points today is taken by industry veteran Symbol. In addition to the radio (802.11b or 802.11a/b in dual mode), there is only one omnidirectional antenna on the access points in the WS 5000 WLAN Switch system (see Figure 5). The intelligence is completely embedded in the switches. The goal is to minimize the cost of access points, including in large installations. To distinguish them from regular access points, Symbol refers to them as WLAN switch access ports.

When an access point is overloaded, the WLAN switch tries to find a less congested access point within range, to which the user is immediately transferred. Other WLAN switches support this load balancing, but Symbol advertises “forward” load balancing. Even before it reaches the critical overload of the access point, the switch will identify a threatening trend and find an alternative to access. With Airbeam, Symbol offers a security solution for its WLAN switches that allows you to organize the VPN connection between participants according to your own settings. A feature of this solution is end-to-end implementation – VPN functionality is a standard offer of all companies except Trapeze.

Aruba follows a similar philosophy of simplifying access points. Its access points also lack most of the traditional features, with one exception: in the Aruba 5000 system, they have one feature – a monitoring function to observe the surrounding area and instantly identify “untrusted” access points (see sidebar “Untrusted Access Points” ). If, for example, someone tries to use an unauthorized access point in the corporate network, the monitor will immediately notify the switch and the administrator. After that, within the framework of predefined procedures, it is even possible to automatically isolate an unauthorized access point and suppress all access attempts for WLAN users. With the help of the monitor, Aruba is able to calibrate the radio emission of its access points on the territory or in the building in real time. Moreover, when an access point fails, neighboring points are automatically reconfigured so as to cover the resulting free sector in the radio emission.

Trapeze has also centralized control and management functions in its switchboard. However – and this is the difference between its approach and all the others – the solution does not use a VPN, but offers features to support the quality and class of services provided (Quality of Service, QoS). Trapeze believes that encrypted tunnels are too complex to handle and too time consuming to build, especially in the case of voice services. The necessary security measures should be provided by various encryption technologies built into the access points.

Trapeze’s WLAN Mobility System differs in software. Along with the switch (Mobility Exchange) and access point (Mobility Point), the solution includes a package with system software, as well as the RingMaster Tool Suite. Under one shell, functions are integrated that will be useful to the administrator already when planning and designing the network, since, according to the manufacturer, they make time-consuming measurements inside the building unnecessary. Building plans in Autocad, JPG and TIF formats can be read and used directly as a planning basis. The capacity calculation is done mostly automatically, including for the case of network expansion. In addition, RingMaster offers numerous management tools, among which Trapeze, not least due to its approach to identity-based security, includes advanced user administration.

Nortel develops WLAN switches not only for enterprises, but also for carriers and service providers. The WLAN Security Switch 2250, together with the WLAN Access Point 2220, offers support for a range of features for use in public hot spots. These include the property of “double image” (Dual Image), when the access point switches to the standard mode of operation when its operating parameters are lost. Necessary repairs can thus be delayed until an appropriate time, rather than carried out immediately. The access point supports IP roaming across different domains, including between 802.11a and 802.11b networks. What’s more, the Nortel program also lists the WLAN Mobile Voice Client i2050 to support wireless IP telephony via PDAs.

SWITCH AND ACCESS POINT – A GOOD PAIR

So, in order to attract the attention of the consumer, manufacturers equip their solutions with a number of specific functions and capabilities. And when dividing functions between the switch and the access point, each finds its own measure of balance. This leads to a welcome diversity, but, on the other hand, has a serious drawback. A particular switch works only with specific non-standard access points: the components related to a certain solution can meaningfully be used only with “their” WLAN switches, and the latter, in turn, perceive standard access points only as “second-class” devices. True integration of standard access points with centralized management is also hardly possible, as is automatic provision of configuration parameters. Symbol, however, plans to release software that can solve these problems. With respect to the WLAN switch from Symbol, standard access points will behave the same as their own access points. Migration from conventional to switched wireless LANs would certainly make this process easier.

In the case of Trapeze, “alien” access points appear in the floor plans of the RingMaster software, but only when their configuration parameters are entered manually. However, if Trapeze mobile points are nearby, their channel numbers and transmission power are automatically adjusted according to the available access points. Thus, integration into a centralized control system seems to be the best option for using standard access points in the near future. However, specific functions, for which the WLAN switch and access points must be configured against each other, will not be possible with standard access points for a long time to come.

The lack of tight coupling between the switch and the access point does not apply to server-based solutions from Bluesocket and Reefedge, since they are able to manage absolutely any access point. Chantry follows the same philosophy with its Beacon Master router solution. At least as far as switched wireless network clients are concerned, vendors promise compliance. Every Wi-Fi card in any end device (such as a desktop or PDA) should work seamlessly with any Wi-Fi certified WLAN switching solution. Caution should be exercised if one of the products does not have Wi-Fi certification.

CONCLUSIONS

WLAN switching is clearly in its infancy. There is still much to be explored, developed and tested; there are still relatively few offers on the market – at least outside the United States. But one thing is already clear: With WLAN switching, enterprise wireless will get a new boost. In addition, real-time communications (voice, video, etc.) are moving beyond the cable with the advent of switches. In its more mature state, switch-based wireless networks may at least partly challenge the concept of structured wiring. The interests of all those who have moderate bandwidth requirements may well be satisfied with wireless capabilities in the future.

Stefan Mutschler is LANline’s chief correspondent. He can be contacted at: [email protected].

? AWi Verlag

Untrusted Access Points

Only access points that are trusted by the IT department should be present in a corporate environment. However, in reality, individual divisions of enterprises may have many access points that employees have installed themselves, without the knowledge of the administrator. Often, these points have full free access to the corporate network, but often do not provide even a basic security configuration, as a result of which the entire security policy of the company is no longer valid.

In this situation, an additional function of the WLAN switch can help: identifying similar access points and distinguishing them from “neighbors” with interference. However, today not all manufacturers solve such an urgent problem. And those who are trying to do this offer a variety of options. The main approaches to this issue will be illustrated by the example of the philosophy of Trapeze and Aruba. In addition to them, Airflow, Airspace and Symbol are engaged in serious development.

In the case of Trapeze, the IT manager can instruct Trapeze’s own access points (called “mobility points”) to conduct a coordinated RF scan. At the same time, the mobility points report each received radio signal in their coverage area to the RingMaster software, which compares this information about 802.11 wireless transmitters with the access points indicated in the floor plan. If any discrepancies are found, RingMaster shows the corresponding access point, including its position on the plan. From which the IT administrator can draw the necessary conclusions.

Aruba provides the Air-Monitor feature: by default, it runs all the time, i.e. the administrator does not have to run it (the reason is simple: Aruba uses monitoring to automatically calibrate the network). Aruba also compares the scanned data with existing MAC and IP configurations and thus detects access points installed without the knowledge of the IT department. In the case of Trapeze, the IT administrator will have to check whether the access point is dangerous, has access to the corporate network, or is it just a “neighbors” point, while in the case of Aruba, the system itself proceeds with further actions. By controlling both the air and the local network, the system is able to classify access points and at the same time distinguish points with access to the corporate network (dangerous) from those that cause only radio interference. Access points classified as “dangerous” are automatically quarantined and users will no longer be able to access them.

D-Link

Question: Universal (wired and wireless) D-Link access system based on DWS-3160 switches

Answer:

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