The Internet uses Internet Protocol (IP) as its exclusive Layer 3 network protocol. Corporate networks, however, have run many other protocols over the past 20 years and find themselves wanting to migrate to an IP-only network. IP has become the de-facto network protocol for nearly every data-based application.

However, other network protocols still in existence are Layer 3 routed protocols such as the NetWare Internetwork Packet Exchange (IPX) and AppleTalk and layer-bridged protocols such as Systems Network Architecture (SNA) and NetBIOS. Today’s routers and switches allow these other protocols and IP to coexist on the same physical network.

Managing multiple networks adds complexity and extra cost. Companies are working to converge as much network traffic as they can into single-protocol IP networks. The advantages to a converged network include the following:

The primary mechanism for converging traffic onto a common IP network involves tunneling. Simply put, IP tunneling is the process of putting one type of packet into an IP packet. The packet traverses the IP network to the IP destination, in which the receiving device extracts the original packet from the IP packet and then passes it onto the destination device on its native network.

Cisco is a prominent player in multiple non-IP network markets primarily because of its ability to tunnel. Examples of technologies that can tunnel through IP networks include the following:

Because these technologies tunnel through IP networks, they benefit from IP services such as QoS and availability functions such as Hot Standby Router Protocol (HSRP). As a result, you can apply a single comprehensive strategy for prioritizing important traffic and handling network outages across application types.

The singular approach also presents problems that network designers must address. Certain SNA protocols require quick and consistent response time. As a result, network congestion that prevents tunneled SNA traffic from achieving expected response times can result in loss of connectivity to a mainframe.

The same applies to tunneling telephony. Network congestion can detrimentally affect the quality of one or more calls. The caller whose call meets congestion will experience strange choppy conversations or notice his call drop altogether. For companies consolidating their telephony and IP networks, a lack of quality can prohibit a successful rollout.

As a result, you must give special consideration when migrating one network technology, such as SNA or telephony, onto another such as IP. You must design the network in such a way that the network devices have enough bandwidth and processing power to deliver time-sensitive traffic while throttling back less sensitive traffic.

You can also use tunneling for security purposes. For example, corporations might want their employees to access the corporate network from the Internet. Although firewalls and other systems can protect the internal networks, corporate traffic traversing a public network can still be a problem. With readily available tools, hackers can intercept and perhaps alter the traffic as it travels between the Internet-based employee and the corporate network.

Through the use of protocols such as Internet Protocol Security (IPSec), the corporation can encrypt (scramble) the traffic such that it cannot be recognized unless the user knows certain keys. IPSec essentially tunnels the corporate traffic in the following way: Before traffic hits the Internet, a device (such as a router or PC) encrypts the contents of the traffic.

Generic routing encapsulation (GRE) is a type of tunneling that lets you tunnel any type of traffic. GRE is often used to tunnel unroutable protocols through an IP network.

Aside from tunneling, application and file server vendors are migrating their traditionally proprietary protocols to IP. For example, Novell NetWare and AppleTalk operate natively over IP.

At-A-Glance—IP Convergence

<division> <title>Why Should I Care About Internet Protocol Convergence?</title>

Over the past several years, many protocols have competed for a dominant position among users, and the Internet Protocol (IP) is the winner. With the positive results of network effects (where more users create the need for more applications and services, which draws still more users, and so on), most companies have converted their networks to IP. Virtually all new networks and devices, from computers, to phones, to wristwatches, are compatible with IP.

IP has many benefits over other protocols, especially with the ability to transport non-IP protocols. This benefit helps companies still using legacy systems because it gives them the ability to fully convert to IP at a pace that makes sense for them.

</division><division> <title>What Are the Problems to Solve?</title>

Converting to IP can be a slow and expensive process, and many companies want to use IP to transport their information across a WAN but keep their legacy systems in place. Using IP as a third-party transport requires that the original data be modified in some way. IP uses a process called encapsulation to transport the data through point-to-point tunnels (tunneling).

Although all this movement toward convergence is good for IP, the huge increase of traffic on IP networks sometimes results in congestion, which can seriously affect the quality of time-sensitive information such as live voice data. IP’s ability to use quality of service (QoS) allows network administrators to prioritize certain types of traffic, which can be expedited through the network.

IP convergence can also address the issue of security. IP uses a public network for long-haul transport of information, which means that companies risk their private information being eavesdropped or stolen. Security schemes such as Internet Protocol Security (IPSec) allow strong encryption so that if information is stolen, it is unreadable.

</division><division> <title>Who’s the So and So Guy?</title>

One of the biggest issues with maintaining separate networks is the staffing requirements for maintenance, upkeep, and after hours (on-call) personnel. Whenever assistance is needed, the first question tends to be “Who is the so and so guy?” where “so and so” refers to the network in question. By running separate networks, companies spread their support resources thin among competing interests such as IP, time-division multiplexing (TDM) voice, and other legacy systems such as Systems Network Architecture (SNA), AppleTalk, or other proprietary protocols. The choice then becomes hiring additional staff or overworking existing staff, risking burnout.

With IP convergence, you can train all IT staff on a single protocol and support a single converged network.

IP convergence is the concept of tunneling one type of network through another. Examples include the tunneling of SNA through an IP network, and encrypting IP traffic and tunneling the encrypted data through an unsecure IP network.

The sender drops a packet in its native language into a standard IP packet, which is then sent across the IP network to its destination. At the IP destination, the native packet is extracted from the IP packet, and then sent on its native way.

The key to tunneling is to make the IP network in the center invisible to the endpoints.

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