Telco Small to Medium Solutions

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3.2.1.2 Hardwaresoftware

VPNs and WANs require the same types of equipment at this level. ISDN or frame relay routers are available through such manufacturers as Cisco Systems, Farallon, Motorola, and Ascend Communications. Both sides of the connection require a router, which connects to the local ISP. The WAN requires no extraneous software to complete the solution. Use the same networking protocol on each end and the network is functioning. The VPN solution requires software of some kind to allow secure access to the central network. SSH, L2F, L2TP, and PPTP are solid solutions for small to medium network-to- network connections. Note that dedicated or specific hardware may be needed to support any of these VPN solutions. SSH is available for Unix servers, L2F and L2TP are supported on Cisco routers running IOS including ISDN and frame relay routers, and PPTP is currently available on Windows NT 4.0 Server, as well as some ISDN routers. Also note that these softwarehardware combinations are required on each end of the connection.

3.2.1.3 Administration

Expertise for a traditional WAN setup should be in a typical network administrators skill set. Total set-up time for both sides of the WAN should not exceed 10 to 20 hours, which includes tracking down the best equipment, ordering lines, and configuring the connection. These types of connections do not usually require much recurring maintenance, as they tend to stay solid once properly configured. As much as 10 hours a month in maintenance time is standard, even if there are major connection or configuration problems. The main failure point in this kind of connection is the telco provider, because they dont tend to communicate with their customers when lines are undergoing maintenance or fail completely. Another recurring issue is training end users in the use and general maintenance of the connection, as this scenario would not need a dedicated network administrator on both ends. When implementing a virtual private network, the initial consideration for a network engineer is research and training. Most network administrators need to know how a VPN works and how it fits with the organizations networking needs. This book should get the process started, but an internal needs assessment should be done as well. Initial setup of a VPN will consume a significant amount of time, possibly as much as 20 to 40 hours, including research, training, pitching the solution upstairs, and actually implementing the network. Recurring maintenance shouldnt be significantly different from the WAN solution presented earlier with two exceptions: the ISP used and security of the VPN. Both issues are discussed at length later in this section. However, suffice it to say that the network administrator can add about 5 to 10 hours a month to the WAN maintenance estimate a maximum of 30 hours total per month for dealing with security and the Internet service provider.

3.2.1.4 Security, scalability, and stability

The WAN connection is arguably the most secure and stable solution for a network of any size. The connections are entirely private and are using proven, industry standard technology. Any questions concerning the stability of a WAN would affect any network, LAN, WAN, or VPN. Failures of equipment, protocols, systems, and server, for example, while not common, 47 are a fact of life for any network. Where remote-to-central connections are concerned WAN and VPN, the additional failure point is the telco provider. These are beyond the network administrators control, for the most part, and the selection of a telco provider that communicates problems and planned downtimes to its customers is the best bet. VPNs strength is not its stability, in a general sense. VPNs are a new technology, running on an inherently unreliable technology the Internet. When dealing with Internet routing issues, communication between various platforms, encryption processes and the like, you can expect a less robust system. But as the world moves more to an interconnected society and as real standards emerge protocols, hardware, etc., VPNs will have a stabler base on which to operate. The real differences between the VPN and the WAN come to light when scalability is considered. Moving from our simple smallmedium to a large WAN requires a serious investment in equipment, workforce, and telco lines, especially when adding multiple networks across a nationwide organization. The main cost difference would be line charges for the upgrade. If the central office had to upgrade to a T1 with all the equipment necessary for this, the remote sites would likewise need at least a fractional T1 with the equipment necessary to make this work. With the VPN, initially only the central network would need an upgrade in bandwidth and equipment, even to accept connections from multiple networks. Then, boosting the VPN servers capacity becomes minuscule when compared to the equipment and line upgrades on the WAN solution.

3.2.2 Large Solutions

Large WAN or VPN scenarios can encompass many different configurations, from multiple large interconnected networks to a central network connecting many smaller networks. For simplicitys sake, we present the two scenarios in Figure 3-5 .