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Dedicated LANs

This technology, sometimes called Ethernet switching (or LAN switching), can provide a dedicated LAN segment for a single station. Multiport servers and "power user" applications require this technology, for example.

In the case of multiport servers, shown in Exhibit 2-3-3, a server can have multiple 10M-bps connections active simultaneously from multiple, independent Ethernets. Exhibit 2-3-3 also shows that a power user can effectively have a dedicated port on a server while still being able to communicate with the rest of the enterprise.


Exhibit 2-3-3.  Ethernet Switching

In many ways, this is the ultimate segmentation solution and, as such, it preserves investment in the existing Ethernet infrastructure while allowing higher-bandwidth communication. In addition, it allows the sharing of resources, such as servers, among separate segments.

Backbone Connections

The hub of the future (as shown in Exhibit 2-3-4) supports uplinks to the backbone of various types, including connections to a collapsed backbone network using bridge/routers, direct connections to a backbone LAN such as FDDI, and connections to a backbone switch or router either through a dedicated LAN connection or an ATM connection.


Exhibit 2-3-4.  Ideal Hub of the Future

Routing

The hub incorporates integrated routing to tie the various LAN segments together and to attach to the backbone. This routing hub becomes extremely important when the backbone service is ATM but the attached stations are using traditional LAN technologies.

Virtual Networks

As organizations grow and change, users and their resources are constantly moving within the enterprise. Virtual networks are built using software from physical networks. Virtual networks require dedicated LAN connections to each user and each resource.

Although the cost to provide dedicated LANs to an entire enterprise may be noticeably higher as compared with traditional shared LANs, it is likely that portions (and sometimes all) of an enterprise will be able to operate with virtual network software that allows administrators to group together users and their resources, regardless of their physical location. Virtual networks also allow logical grouping for bandwidth planning, security, and private workgroup administration.

Port Switching. With current state-of-the-art technology, virtual networks require that users be placed on the most appropriate physical LAN. This is done through port switching, which is the ability to configure a user to one of the physical LANs in the routing hub. The port switching capability provides cost-effective virtual networks even as dedicated network ports become more widely used.

Expanded Internal Throughput

To provide both inexpensive, shared LAN connections as well as higher-speed dedicated LAN connections and ATM connections, the hub must contain two kinds of internal slot-to-slot connections: true LAN media and a high-speed connectivity option.

The LAN connections allow cost-effective concentration of the major LAN station technologies—namely, 10M-bps and 100M-bps Ethernet, 4M-bps and 16M-bps Token Ring, and FDDI, which are available today, and 1G-bps Ethernet in the near future. The high-speed alternative provides the bandwidth and characteristics required for dedicated LAN and ATM support.

SUMMARY

The trends in technology and applications mean that network managers face an increasing demand from users of business applications for bandwidth to the desktop. No matter which road network managers take, routing hubs are going to emerge as the primary means of connecting desktop devices to local backbones. The principal reasons are the ability of routing hubs to connect networks of different speeds and media types and their ability to segment the network internal to the hub—functions that cannot be performed with traditional wiring hubs designed primarily for repeating functions.


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