Upgrading from 10BASE-2 or 10BASE-T
Twisted-pair wiring pretty much
100BASE-T and gigabit Ethernet solutions are now the de facto standards for creating a new network. If you're creating a network from scratch, it's best to start with the latest and greatest if your budget allows.
Like 10BASE-2 networks, you should ask yourself why you would even want to
For more information about network topologies and how the physical network should be laid out, see Chapter 3, "Network Design Strategies."
For this reason, this chapter skips upgrading from 10BASE-2 to 10BASE-T because such an upgrade really isn't a good investment. If you're going to swallow the expense of pulling new cabling to replace older coaxial cabling, there's no reason to go to 10BASE-T today. Category 5 cabling can handle both, and almost every network adapter card produced today can operate at 10Mbps as well as 100Mbps. After you've upgraded the cable plant, you might as well go for the added bandwidth of 100Mbps instead.
The rest of this chapter quickly looks at some of the things to consider when planning to replace an older Ethernet network with more modern technology.
Hardware and Software Factors to Consider for 10BASE-2, 10BASE-T, and 100BASE-T
Obviously, it's the hardware that you'll have to replace when making this kind of upgrade. Network protocols, such as TCP/IP, don't care what the underlying physical network is made up of as long as they can get data segments from one place to another. However, you might still be using older software, and if so, you might want to consider upgrading it in addition to the hardware when you plan for this kind of upgrade. As discussed in other
For a historical overview, 10BASE-2 and 10BASE-T have more differences than just the type of cables they use. Although both of them use the same messaging technique (CSMA/CD), their topologies are basically different: 10BASE-2 uses a bus topology, whereas 10BASE-T (and 100BASE-T) installations use a star topology, implemented by a switch, although you might find an older hub still being used. The distances that can be covered by cable segments are also different. The network adapters transmit signals at different speeds. When preparing for an upgrade, check your network inventory to determine which parts of the hardware you'll have to upgrade in addition to the cabling. The major considerations that need to be researched when upgrading from 10BASE-2 to a twisted-pair network are as
To learn more about how hubs and switches function, see "Bridges, Repeaters, and Hubs," on the upgradingandrepairingpcs.com Web site and Chapter 8, "Network Switches."
For example, if you're using a multiport repeater, replacing it with a more functional hub or switch seemed a natural thing to do a few
Chapter 14, "Ethernet: The Universal Standard," covers in more detail the different cabling distances you'll need to consider.
Today, however, using switching technology to replace hubs is about the only option you have today. As stated earlier, you'll find it difficult, if not
The main consideration here is the topology requirements used for earlier Ethernet networks. If the cable doesn't provide the distance or bandwidth requirements you need today, you'll have to replace the cabling to accommodate modern networks. In a small LAN environment, this usually isn't the case. In a larger environment, you might have to replace cabling to reach the distances you need, yet still provide the same bandwidth that older equipment (such as hubs) can give to users.
Because 10BASE-2 uses thinnet coaxial cabling, the first upgrade issue you must address is getting the appropriate network cabling.
This should be the simplest decision you have to make. Although it's quite possible to use Category 3 wiring to construct a 10BASE-T (and even a 100BASE-T) network, the only good reason I can think of to do so would be that you already have the wiring in place and can use it with few modifications. Other than that, if you're going to install a 100BASE-T network to replace a network based on coaxial cables, you would be better
Both of these technologies require Category 5 cables or higher. Although it might seem like Gigabit Ethernet is something that's far in the future, keep in mind that many network administrators didn't think that video on demand would be a requirement today. It's easy to underestimate the network bandwidth that you'll need for future requirements. And because installing the cabling is one of the most labor-
The amount of cable you need might work out to be a lot more than you used for the 10BASE-2 network. Remember that in the bus topology that thinnet (coaxial) networks such as 10BASE-2 use, you can daisy chain one workstation to another using a linear bus. A 50-ohm terminator terminates each end of the bus. The total amount of cable needed is simply the sum of all the cables that are daisy chained together. When using a hub or switch, you can have two workstations sitting right
If you instead use a multiport repeater on an existing 10BASE-2 network, and if only one computer is attached to each port, you'll find that replacing the cables is a simple matter of stringing Category 5 (or greater) cables through the same route used by the current coaxial cables. Then all you need to do is replace the repeater with a switch. If you have segments on a multiport repeater that have more than one computer attached, you'll have to plug each computer into a separate port on a switch. Another possibility is to place these computers on a separate switch and connect it to the network backbone.
Because you must string cable from a central location to each workstation, you need to have a place you can use as a wiring closet to store the switch and any other
For all practical purposes, consider making backbone connections using fiber-optic cabling. Doing so will give you a much faster connection between LANs today and better prepare you for the future. Keep in mind that the old 80%/20% rule no longer applies. This rule stated that 80% of network traffic remained in the local LAN and 20% was sent to another segment of the LAN. Today, it's more typical to centralize large servers in a computer room and keep LANs separated by switches. Because computers on the LAN need to access these servers, and they might be separated by multiple switches or even routers, you should consider the 80%/20% rule to be
Network Adapter Cards
If you had the foresight to purchase the kind of network adapter cards called
, which have connectors compatible with both BNC connectors and RJ-45 connectors (see Figure 57.1), this is one piece of hardware you might not
Figure 57.1. A combo card contains connectors for both thinnet coaxial cables (BNC connectors) and a receptacle for an RJ-45 jack used with twisted-pair wiring.
To learn about the latest developments in network adapter cards, including technologies such as auto-negotiation, WOL, and even newer stuff such as PC Cards and wireless network adapters, refer to Chapter 7, "Network Interface Cards."
If you're going to have to upgrade a large number of workstations to newer NICs, think
Network Cable Connectors
As already pointed out earlier in this chapter, a 10BASE-2 network uses a different kind of connector than a 10BASE-T/100BASE-T network does. You should pay attention to the details when ordering connectors (if you plan to make cables yourself) or when ordering ready-made cables that have the connectors attached. When upgrading to twisted-pair wiring, I've already suggested that you use Category 5 cabling (or greater) instead of a less capable variety, such as Category 3. This enables you to use the cabling later when you decide it's time to install 100Mbps segments on part or all or part of the network. Keep in mind that Gigabit Ethernet adapters are already available and the standard for 10 Gigabit Ethernet has just been approved. Although you might not find these speeds required for a workstation connection, they will probably figure into server and backbone connections in just a few years or even less. And because
Connectors, like cables, can exhibit different performance characteristics depending on how they're manufactured. Be sure that the RJ-45 connectors you choose are compliant with the specifications for Category 5 cables. Inferior connectors can cause a lot of trouble later (such as noise or
In Chapter 6, you'll find more information about cables and connectors and the problems you can encounter when they aren't manufactured correctly.
Bridges, Hubs, Repeaters, and Switches
To extend the length of a LAN based on 10BASE-2 technology, the standard technique is to attach multiple segments with a bridge or a multiport repeater. A repeater works similar to a hub: It simply makes one large broadcast domain out of the various cable segments that are connected to it. A bridge connects two segments, but is capable of learning MAC addresses. Therefore, a bridge can reduce traffic by passing on
For more information about bridges and how they operate, see "Bridges, Repeaters, and Hubs" on the upgradingandrepairingpcs.com Web site.
You can use bridges on a 100BASE-T network for the same purposes you would use them in 10BASE-2. They can
Network applications are becoming more data intensive than ever before as computers become faster and more memory is added. A switch creates a small collision domain (that is, just the switch and the computer attached to a switch port) and can drastically reduce network congestion.
Also, in anything but a small network, you might need to use more than one switch to connect
A more important factor to consider when evaluating a switch is to find out whether it comes with management software that's compliant with SNMP and RMON standards. Check to find out whether each port can be set to a different speed. If it can, make sure that you know whether it's autosensing or if you must manually set it to operate at one speed or the other.
The Simple Network Management Protocol (SNMP) and RMON (Remote Monitoring) are discussed in detail in Chapter 53, "Network Testing and Analysis Tools."
If your existing network already uses a router to connect to a larger network, be sure that the hub or switch has a receptacle that can be used for the router connection. Most routers made today accept cables
For more information about using routers to join individual network subnets, refer to Chapter 10, "Routers," and Chapter 37, "Routing Protocols."