D-Link DES-3326 manual Introduction, Layer 3 Switching

DES-3326 Layer 3 Fast Ethernet Switch User’s Guide

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INTRODUCTION

This section describes the Layer 3 functionality and Layer 2 and Layer 3 features of the DES-3326. Some background information about Ethernet/Fast Ethernet, Gigabit Ethernet, and switching technology is presented. This is intended for readers who may not be familiar with the concepts of layered switching and routing but is not intended to be a complete or in-depth discussion.

Layer 3 Switching

Layer 3 switching is the integration of two proven technologies: switching and routing. In fact, Layer 3 switches are running the same routing routines and protocols as traditional routers. The main difference between traditional routing and Layer 3 switching is the addition of a group of Layer 2 switching domains and the execution of routing routines for most packets via an ASIC – in hardware instead of software.

Where a traditional router would have one, or at best a few, Fast Ethernet ports, the DES-3326 Layer 3 switch has 24 Fast Ethernet ports and optionally, 2 Gigabit Ethernet ports. Where a traditional router would have one or two high-speed serial WAN connections, the DES-3326 relies upon a Fast Ethernet port to connect to a separate device, which in turn, connects the network to a WAN or the Internet.

The DES-3326 can be thought of as 24 Fast Ethernet Layer 2 switching domains with a wire-speed router between each domain. It can be deployed in a network between a traditional router and the intranetwork. The traditional router and its associated WAN interface would then handle routing between the intranetwork and the WAN (the Internet, for example) while the Layer 3 switch would handle routing within the LAN (between the Fast Ethernet Layer 2 domains). Any installed Layer 2 switches, and indeed the entire subnetting scheme, would remain in place.

The DES-3326 can also replace key traditional routers for data centers and server farms, routing between these locations and the rest of the network, and providing 24 ports of Layer 2 switching performance combined with wire-speed routing.

Backbone routers can also be replaced with DES-3326 and a series of DES-3326 could be linked via the optional Gigabit Ethernet ports. Routers that service WAN connections would remain in place, but would now be removed from the backbone and connected to the DES-3326 via an Ethernet/Fast Ethernet port. The backbone itself could be migrated to Gigabit Ethernet, or faster technologies as they become available.

The DES-3326 accomplishes two objectives. First as a tool to provide high-performance access to enterprise data servers and infrastructure, and second, to enhance the performance of network equipment already installed. Many network segments display poor performance, but the Ethernet wire is only carrying a fraction of its total traffic capacity. The problem is not the network, but the ability of the connected devices utilize the full capacity of the network. The DES-3326 can eliminate network bottlenecks to high-traffic areas, and improve the utilization of the network’s installed bandwidth.

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