Users and administrators always want more bandwidth on their Lans - that is a fact of networking life. Bandwidth has simply not kept pace with the abilities of software, with the consequence that for increasing numbers of networks, 10Mbps Ethernet and 4Mbps Token Ring are simply no longer good enough. So what's the next step? For many network managers, Fast Ethernet seems like a sensible medium-term solution, even if it does not offer an answer to all future challenges. At a stroke it increases bandwidth, thus answering the most common problems posed by today's client/server, multimedia applications.
Of course, Fast Ethernet comes in more than one flavour - the two main ones being 100VG and the other 100BaseT. In this benchtest we review six leading 100BaseT hubs, each suited in its own way to a different type of network. Within the 100BaseT standard there are three different types of encoding scheme for three different types of media. There is 100BaseTX, designed to run over two pair category 5 unshielded twisted pair (UTP).
There is 100BaseFX, designed to run over a pair of fibres. And there is 100Base T4, designed to run over category 3 UTP by using all four pairs in the cable. Fast Ethernet hubs are also either class I or class II.
A class II hub simply rebroadcasts the signal coming in on one port to the other ports, in the same manner as 10BaseT. This means that all ports must use the same media and encoding schemes. A class I hub is more sophisticated since it decodes the signal coming in on one port and re-encodes and transmits it to other ports. The advantage is different media on each port, but the disadvantage is high internal latency.
The main thing to remember is that there is a wide variance within the world of Fast Ethernet hubs, and your customer will want help in deciding which solution suits their specific needs and size of network.
Hopefully this guide should offer some sort of starting point.
3Com Link-Builder FMS 100
This versatile product is both rackmountable and stackable. There are two stacking connectors on the back of the hub, one labelled 'up' and the other 'down'. These look like SCSI2 connectors and can be used to daisy-chain a maximum of eight hubs. The cable needed to stack the hubs is an optional extra. A management module that provides management facilities for an entire stack of hubs is available as a further optional purchase.
It will take up one of the eight units in the stack, so only seven can be managed.
The LinkBuilder has a good range of activity and LED lights that present a variety of status information. As well as the standard activity, link and partition lights for each port, the 3Com hub includes a set of LEDs that correspond to fan failure and temperature. If a management unit is installed, temperature conditions can be reported to a management console, but the LEDs are a useful backup and can alert the user if an unmanaged hub runs into problems. The hub has two LEDs that indicate whether the hub is operating in class I or class II mode. As the hub only operates in class I mode at present, this is redundant information.
For a stackable configuration, the hub has a seven-segment display that indicates a hub's unit number. This shows the hub's position in a stack, and which unit number is dynamically assigned at start-up. Unit number one is at the top of the stack, and unit eight is at the bottom. The 3Com hub includes a slot for a transceiver interface module.
The 3Com hub comes into its own on a larger network that has multiple hubs and management modules. Many of its features are only available when it is part of a stack. For example, the hubs can be configured to power up with all ports disabled, allowing you to enable only the ports that you want. Consequently, any faulty devices connected to the Lan can be excluded. The main problem with the Linkbuilder is that it is a class 1 device. If you can construct the network topology to use class I devices and stack the hubs together, the 3Com will suit your needs.
Compaq Netelligent 3612
This was originally a Networth product, now rebadged under Compaq's Netelligent band name. It is available in two forms: the 3512 version, which is unmanaged, and the 3612, which includes an installed network management module. The 3612 is a stackable unit that allows up to five hubs to be stacked as a single unit. he hub uses that same type of connector as the other stackable hubs we tested, and a cable that allows stacking capability is an optional extra. Up to five units can be stacked, with a single hub managing the stack.
Other features in the hub come into their own when the hub is arranged in a stacking configuration. There are three collision domains on the backplane that are used to stack the hubs. Each of the hubs can be assigned to one of the collision domains, effectively segmenting Lan traffic and thereby reducing the number of collisions.
An optional utility called Hubview is a Windows-based program that allows you to set up these features using drag-and-drop. Compaq also plans to introduce features into Insight Manager to manage these hubs. Netelligent includes MAC address security, so MAC addresses can be locked to particular ports. An attempt to access the Lan by disconnecting one PC and replacing it with another would therefore be defeated by the network card's different MAC address. Another useful feature is the smart uplink module (SUM) that allows repeaters to be linked without the usual hop limitations characteristic of Fast Ethernet.
This is basically an excellent hub with a large number of innovative features, aimed at corporate users with 100Mbps network. It would be well suited for those building a larger corporate Fast Ethernet Lan, and is in all honesty hard to fault in any way. The price of the end-user configuration supplied is u1,870 for the managed version, and u2,510 for the unmanaged version.
One of the vendors reviewed here, who shall remain nameless, spoke disparagingly of Compaq's network offerings on the grounds that networking is not a core business for them. It has however bought in expertise wisely, and deserves respect.
Bay Baystack 100
This not one of the most flashy hubs we reviewed, in the sense that it is not festooned with banks of flashing lights. Instead, an unobtrusive panel in the right hand corner displays all the information you are ever likely to need. There are 12 UTP ports and two expansion slots, one of which is the media adaptor slot. The media adaptor slot can currently take a fibre uplink port, but there are plans to add a 100BaseT4 uplink port. The management unit has two ports on the front, a 9-pin RS232 console port and a 25-pin management port. There is no difference between the ports which can both be connected to a local console. There are plans to enable the 9-pin port to connect to a local console. The 25-pin port is designed for a modem, to enable remote out-of-band management. In future, the 25-pin port will be aimed at sophisticated graphics-intensive management utilities.
As well as the management unit, the hub stacks up to eight hubs in a single stack. The Baystack 100 uses the same type of connectors as the 3Com Linkbuilder, but unlike the 3Com product, the management unit does not take up a unit place in the stack, allowing eight hubs to be managed.
The redundant power supply module provides DC power for up to four hubs, so an eight-hub stack will require two redundant power supply modules.
The status panel has 24 LEDs for each port. The model that we reviewed had 12 ports, but it can be upgraded to a 24-port hub by replacing the management unit with a module that provides an additional 12 UTP ports.
Although a single management module can manage a stack of hubs, you can install a second management module for each stack. This provides redundancy in the unlikely event of either a hub or management module failure. In this scenario, the master network management module (NMM), which must be in the top hub, manages the stack. In the event of a failure the second unit automatically takes over the management of the stack, working from information detailed in the initial configuration. This is a serious hub for the corporate backbone, that can integrate into any management environment with ease.
CNet CNFH 1200
CNet CNFH 1200 is a basic unmanaged hub. It provides 12 unshielded twisted pair ports and an additional uplink port that can be used in place of the twelfth UTP port. The CNet is a class II device and consequently up to two hubs can be daisy-chained, but that is the limit of its expansion capabilities. In addition to the UTP ports, the front of the CNet has an LED that indicates power and collision, and two further LEDs for each port, one for traffic and the other for partitioning.
The minimalist approach to the unit extends to its documentation, which is a single A4-sized sheet. Since the only control on the hub is a power switch on the back, reams of documentation would be difficult to generate.
There are two fans at the hub's rear that provide a degree of redundancy should one fan fail. It also ensures that the hub will remain cool even in a poorly ventilated equipment rack.
For network managers that are looking for a straightforward, no-nonsense but reliable Ethernet hub, the CNet CNFH 1200 is an excellent choice.
It may not have rows of flashing lights or add-ons that other hubs offer (for a price), but it is excellent value for money from the end-user standpoint.
Its limited range of features, sparse documentation and lack of manageability mean that the CNet does not score well against the comparatively feature-laden hubs in this benchtest, yet it is a sound unit with a lot to offer the user looking for a bargain.
If your customer wants a cheap solution for a Fast Ethernet workgroup, they could opt for a smaller eight-port workgroup solutions. If, though, the customer has a structured wiring system and the 19in racks to go with it, the CNet hub represents an equally effective solution. A minimal hub that offers all the features that a user needs and with none of the extras that they might not. It is worth stressing that the hubs reviewed here are not exact equivalents of each other. They divide primarily between workgroup and corporate backbone hubs. The Farallon is unashamedly in the former catogory.
Digital Etherworks 8TX
This is an eight-port unit, and therefore aimed at the workgroup market rather than rackmounted backbone equipment. There are no expansion slots and no power switches. The front of the hub is devoted to a range of LEDs that indicate the hub's status. A range of LEDs indicate load, but the lights do not seem to go all the way up to 100 per cent. As well as a meter to show utilisation, a further meter indicates collisions. Together, these meters provide an at-a-glance status of the workgroup, and they can be used to manage the workgroup load. If either the red collision or red utilisation LEDs consistently illuminate, this indicates that the you are attempting to push too much traffic through the workgroup and need to make adjustments accordingly.
In addition to the meters, there are two LEDs for each port: one link/traffic LED that lights up to show a link and flashes to indicate traffic; and a partition LED. When a port has been partitioned, a red LED lights up above the port which normally indicates a problem with the workstation connected to that port. A partitioned port is isolated from the Lan, and will automatically rejoin when the problem has been fixed. Typically a part may be partitioned simply because of excess network traffic, in which case it will correct itself almost immediately. If you see an active partition light on a particular port, it probably means that either the network card is faulty, or there is a problem with the software on the workstation.
There are eight RJ45 ports and an optional uplink port at the back of the hub. The uplink port is simply an RJ45 connector with the transmit and receive pairs swapped over, allowing you to link two hubs with a single straight cable. The Etherworks TX8 has no expansion capabilities. as a class II device one can, of course, link two hubs by using the uplink port on one of the hubs, or connect it into a Fast Ethernet or ATM backbone through an appropriate routing device. The unit will sit unobtrusively on a desk or file server, and is quiet in operation. It makes an ideal workgroup hub.
Farallon Fast Starlet 100TX/8
The Farallon Fast Starlet is an eight port workgroup hub. Despite its unusual blue and grey colouring and its shape, the Fast Starlet has certain features that make it a good Fast Ethernet workgroup hub. All connections are made at the rear of the hub, where there are eight UTP ports, a power socket and, somewhat surprisingly, an on-off switch. Most manufacturers do not bother with an on-off switch, as a hub is likely to be plugged in and left running continuously which makes a power switch redundant.
An expansion port is a useful feature. In our review model, the expansion port was fitted with a 10/100 bridge card. The Fast Starlet bridge (priced at u865) enables connection to a legacy 10Mbps backbone, allowing users to see resources on the rest of the corporate network, and still have a 100Mbps workgroup locally. This is a major concern if the user is buying the hub to allow a small workgroup to migrate to Fast Ethernet on a trial basis, as they will still require access to the rest of the legacy 10Mbps Lan. The bridge has two RJ45 connections and an AUI port. The RJ45 connections can be used simultaneously, allowing you to link to an existing 10BaseT network and connect a printer to the other 10BaseT port. The AUI port can be in place of the RJ45 ports. The hub has three lights for each port, comprising receive, link and collision.
Green LEDs indicate linking, those that show partitioning are yellow, while receiving activity is displayed with orange LEDs. This makes a colourful show when the hub is in operation, and adds to its quirky appearance.
Farallon's hub is an excellent solution for small workgroups moving up to Fast Ethernet. As it is a class II hub, it is possible to cascade a second hub off one of the ports to provide a solution for larger workgroups.
The bridge option is a well thought out addition that enables a workgroup to move to 100Mbps independently from the networking infrastructure while maintaining communications with a 10Mbps corporate backbone.
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