all you need to know about enterprise network technologies

Over the last 30 years computer networks have established themselves as a cornerstone of modern business. With the commercialization of the Internet in the 1990s, networks have become fundamental in how companies share knowledge, operate, and interact with customers, partners, suppliers and other third parties.

 

Local area networks (LAN), which linked computers in the same or adjacent buildings, were the first to make an impact in businesses. Nowadays, the wide area network (WAN) is just as important as it allows companies to share information and business applications countrywide or even across the globe. Smaller versions of WANs that offer citywide or regional connectivity are sometimes labeled as metropolitan area networks (MAN).

 

Underlying the flow of all this information is the physical network. Copper cable, fiber optics, satellites and radio waves support the network technologies that send and receive data and give access to information.

 

Over the last five years, two technologies have come to dominate fixed enterprise networks: multiprotocol label switching (MPLS) and Ethernet. Demand for both MPLS IPVPN and Ethernet services are booming. Analyst Infonetics says that worldwide Ethernet service revenue grew 33% to $12.5 billion in 2007, and IP MPLS VPN service revenue grew 20% to $13 billion ; it predicts that both will grow strongly through to 2011.

 

MPLS was first conceived in the late 1990s to improve the performance of IP traffic over the network. For this it uses classes of service that allow enterprises to put time-sensitive applications such as VoIP in a priority class, and batch traffic such as email in a 'best-effort' class. MPLS IP VPNs are popular with enterprises because they offer quality of service and security guarantees, and allow them to utilize a single network for all voice, video and data traffic. Unlike older hub-and-spoke networks, MPLS IP VPNs allow individual sites to communicate directly, which cuts down on the total network traffic and improves performance.

 

MPLS is a packet-switched network; packets entering the network are assigned a label and passed along a label switched path (LSP). This allows a service provider to create private networks for their customers. Another advantage of MPLS is that it can create end-to-end circuits across multiple networks, including ATM, Frame Relay and Ethernet, which allows enterprises to integrate different networks into a single solution. For more details on how MPLS works and its advantages read this tutorial.

 

Ethernet is a much more venerable network technology, having been first conceived in the 1970s. For many years it was primarily a LAN technology, where it eventually beat off all comers to completely dominate in-building networking. More recently, advances in Ethernet technology  have seen it take over the MAN market, establish itself as the next-generation backhaul network of choice for mobile operators and make major inroads into the enterprise WAN. The main drivers for its popularity are: ubiquity, which makes equipment economical; flexibility, as enterprises can scale bandwidth up and down easily; and its support for IP.

 

Carriers have marketed Ethernet services under a variety of names over the years, so to clear up the confusion the Metro Ethernet Forum has defined three distinct services: point-to-point services called E-Line, multipoint-to-multipoint services called E-LAN, and point-to-multipoint services called E-Tree. E-LANs are ideal for multi-site WANs and support differentiated classes of services, much like MPLS IP-VPNs.

 

Internet Protocol (IP) is a protocol for communicating data over a packet-switched network and is the fundamental language of Internet communications. Packet switched means that data is divided up into discrete segments and sent across the network and reassembled at the other end. It is distinct from circuit switching, where a fixed channel is set up between two points for the time of the transmission. The advantage of packet switching is that it allows multiple transmissions to share the same network, so that one ‘converged’ network can carry all information and services – voice, data, and video. It is simpler and more economical for a large enterprise to run operations for the entire organization on a single network. The convergence of voice and data services also opens the way for new multimedia applications like presence-based technology and video-conferencing.

 

Quite simply a managed network is where a service provider will manage the network for its customers. They will offer a service level agreement (SLA) for the network and handle all the traffic engineering, deployment, management and maintenance. The customer will be provided with a router for their site, through which all the traffic will pass. Unmanaged, or self-managed networks, were traditionally popular in the US, but even here managed networks are becoming more popular. Self-managed networks require the enterprise to build, manage and design the network themselves. While the enterprise will have total control, they will also need to have the necessary internal skills and resources. As networks have become more complex, the majority of enterprises have chosen the route of managed network services.

 

The two main network legacy technologies are asynchronous transfer mode (ATM) and Frame Relay. ATM was a backbone network technology used by carriers and large enterprises to connect local-area networks. It provided guaranteed capacity for voice, data and multimedia applications, and dealt well with suddenly demanding levels of traffic. Frame Relay circuits were often deployed in conjunction with an ATM backbone. Sites were permanently connected, using capacity on a service provider’s network at the bandwidth required; any site could communicate with many destinations via one access link. Voice, data and video were relayed in packets called frames which carried the information needed to send them to their destination.

 

The virtual in a VPN allows you to create a private network within a much larger network, such as the Internet or a service provider's backbone. There are two types of VPNs: trusted VPNs and secure VPNs. MPLS IP VPNs are an example of the former. They allow service providers to create virtual circuits within their IP network and sell these as VPN services. MPLS isolates the traffic streams from one another so that customers can share the same network, much like legacy ATM or Frame Relay services.

 

Secure VPNs are designed to carry traffic over unsecured public networks such as the Internet, and include IPSec and SSL VPNs. IPSec technology requires software on the remote machine and uses it to create a secure tunnel through the public network. This encrypted tunnels means that no third party is able to intercept data traveling across the network. Although secure, the IPSec client software is costly to maintain and manage. SSL VPNs are much newer invention and use the secure SSL protocol that is already built into Internet browsers. Instead of providing a tunnel to the corporate network, SSL VPNs provide remote links into specific applications using a browser. Users get secure access to corporate applications through any Internet connected terminal and IT departments get better control over which resources users can access.

 

A multi-site enterprise WAN will typically comprise an access and a core network. Also called backbones, core networks such as MPLS IP VPNs and Ethernet consist of the service providers' high-speed worldwide infrastructure, to which it provides access through a series of points-of-presence (PoP). Access networks are essentially the link between those core network PoP and the enterprise site. Network technologies used here include xDSL, T1/E1, fiber, Ethernet, ISDN, dial-up, wireless networks such as WiMax and microwave, and satellite.

 

The choice of access network depends primarily on the nature of the site being connected to the network. Increasingly enterprises are choosing one DSL broadband to connect smaller sites. The most common version of this is symmetric DSL (SDSL) that offers the same upload and downloads speeds and doesn't suffer from the same contention issues as consumer ADSL. The older staple of T1/E1 leased lines is less common now.

 

Large sites have many more access network options and the choice will depend on the network services they plan on running and the bandwidth required. Companies running MPLS networks are well served by connectivity options as the service can be delivered over just about any network from copper pairs to fiber. Ethernet services typically run over fiber links, with fully scalable bandwidth widely available up to 1Gbps. Sites, especially important locations, will also have a backup network, and these are typically ISDN, or for small locations dial-up. Both of these offer low bandwidth and as such are nowadays only suitable for emergency use.

 

In countries where there is little or no telecoms infrastructure, enterprises are increasingly reliant on satellites. Fixed satellite broadband systems use very small aperture terminals (VSAT) technology to provide interactive multimedia communications and broadband access to the Internet. VSAT technology requires a dish attached outside a building that can download data at up to 4 Mbps, linking to the corporate intranet or Internet. The PC or network is connected to a broadband modem linked to a satellite dish that transmits data to a satellite ground station hub. Here high-speed connections provide Internet access, email, VPNs, VoIP, broadcast and satellite navigation services.

 

Doing business away from the workplace is convenient and productive. IDC expects the global mobile worker population to increase to more than 1 billion in 2011 - just over 30 percent of the worldwide workforce. Mobile workers can connect to their corporate networks through a variety of methods, including traditional dial-up, Wi-Fi hotspots and mobile broadband. Wi-Fi hotspots are available at all sorts of locations such as hotels, airports and coffee shops. Users pay for access to the local Wi-Fi network and can access the Internet, and through a VPN, their own corporate networks. Wi-Fi cannot match the ubiquity of mobile broadband. Using 3G HSPA technology mobile operators are offering multimegabit, low-cost broadband on the move. The key disadvantage currently is the high cost of data when roaming in another country.

 

An emerging contender for the ultimate solution for broadband wireless networks is WiMAX (Worldwide Interoperability for Microwave Access), Wi-Fi has a limited range compared to WiMax, which can connect devices at multimegabit speeds up to 50 kilometers from an access point. WiMax has two varieties: fixed and mobile. In its fixed form, it is useful as an access network for enterprise WANs. In its mobile form, it can provide hotzone-type access to laptops and smartphones.

 

3G mobile provides wider geographical coverage and higher bandwidth. Successful bidding for more radio spectrum could decide whether WiMAX, or an upgrade of 3G, Long Term Evolution (LTE) will prove the winning technology. LTE builds on existing systems and its greater efficiency could lead to affordable wireless broadband services with faster downloads, video sharing, and mobile TV.