The first decision Terra Flora needs to make is which protocol to adopt as the protocol-of-choice for their network, which protocols to retain, and which to abandon.
Terra Flora elected to use Transmission Control Protocol/Internet Protocol (TCP/IP) as their network protocol of choice, while retaining Systems Network Architecture (SNA) protocols for connection to the legacy systems.
TCP/IP is a standard set of networking protocols that govern how data passes between the networked computers. With TCP/IP, Terra Flora networks will interoperate by using the Windows NT Workstation and Windows NT Server platforms with devices that use Microsoft Windows 95, other Microsoft networking products, and non-Microsoft operating systems, such as UNIX.
Many reasons supported the Terra Flora decision to use TCP/IP as the preferred network protocol.
TCP/IP is the primary protocol of the Internet and the World Wide Web. One of the primary goals of Terra Flora is to establish a presence on the Internet, allowing customers, nurseries, retail stores, and manufacturing sites to place orders directly. Terra Flora sees this as essential to keeping Terra Flora competitive.
TCP/IP is a very clean and efficient suite of standard protocols that can be used on both local and wide-area networks (WANs) to provide communications between all the basic operating systems on the network.
TCP/IP has the advantage of already being in place in parts of the Terra Flora network. TCP/IP currently supports communications between all UNIX-based systems and the AS/400 at Terra Flora, and is running on the following equipment.
For a detailed discussion on TCP/IP see Chapter 6, "TCP/IP Implementation Details."
SNA Protocol enables communication between the department and divisions servers and the enterprise mainframe and AS/400 legacy application services. In the near future, SNA will remain, but Terra Flora plans to review the options of moving all the SNA dependent services to TCP/IP in a cost effective manner. If this is not an option, SNA will remain on the network as the protocol to access the legacy applications.
Three other protocols are currently in place in various parts of the Terra Flora networks. The decisions to abandon these protocols as network standards were based on the reasons given in each case, as described below.
In the past, Terra Flora used the IPX/SPX protocol only in the Nursery Products division, to support NetWare services. IPX is easy to install and is dynamic in that it requires no configuration changes for either mobile or relocated network nodes.
Despite these advantages, the expense and performance degradation anticipated under this protocol for such a large and diverse network deterred Terra Flora from establishing IPX/SPX as a protocol standard. The protocol's reliance on network-wide broadcasts make overhead unreasonably high for effective WAN implementations.
IPX/SPX protocol depends on broadcasts of Service Advertising Protocol (SAP) and Routing Information Protocol (RIP) packets for network name-resolution services built into NetWare. SAP and RIP broadcasts are updated every sixty seconds by each server and sent to the entire network. These ongoing broadcasts are negligible within a local LAN environment. However, when IPX networks are connected in an enterprise manner, SAP and RIP broadcasts can dramatically erode the available bandwidth.
For the immediate future, Terra Flora will continue to use IPX/SPX for interchange of files between NetWare and other networking clients. Within the next year, Terra Flora aims to replace all hardware that depends on the IPX/SPX protocol with hardware that utilizes TCP/IP, and to phase out the IPX/SPX protocol.
AppleTalk is a Macintosh-based protocol that runs primarily in peer-to-peer situations and has very limited support on other platforms.
At Terra Flora, AppleTalk has been used locally in the Retail Services division for graphics-art communications between Macintosh computers, which store the graphic software. Due to the small number of machines, the Macintosh computers were hooked together to form a peer-to-peer network.
Under the new Terra Flora plan, Windows NT Server Services for Macintosh will be added to the departmental servers running Windows NT Server, to provide file interchange and primary support for the Macintosh computers and the rest of the network. Although the Macintosh computers don't support TCP/IP, AppleTalk is enabled on the routers, allowing the Macintosh computers to communicate with the Department-level servers running Windows NT Server Services for Macintosh.
NetBEUI is a non-routed, broadcast-based protocol. The master browser on TCP/IP networks cannot see or display computers that use NetBEUI to communicate with the network in the network browser list.
NetBEUI was used as a legacy protocol for networking between Windows 3.1 and MS-DOS clients. Terra Flora has already removed NetBEUI from all bridges and routed networks. Within the next six months, the Terra Flora client computers that rely on NetBEUI will be removed from the network or upgraded to Windows 95. The plan at Terra Flora is that no NetBEUI traffic will exist on any network segment after the next six months.