COMMON LAYER 2 DEVICES AND FUNCTIONALITIES Introduction 7

COMMON LAYER 2 DEVICES AND FUNCTIONALITIES

Introduction 7 6 5 4 3 Routers, PAD’s, X. 25 switches 2 Bridges, LAN switches, ATM switches and terminal servers 1 Transceivers, repeaters, hubs, FDDI concentrators, MSAU’s, modems, terminal adapters, DSU’s, CSU’s, MUX and NIC’s 2

Bridges 7 6 5 4 3 2 1 • Bridges analyze incoming frames, make decisions based on the information and forward the frames to the destination • Bridges operate at the Data Link layer, allowing them to rapidly forward traffic representing any network-layer protocol • Bridges control data flow, handle transmission errors, provide physical addressing and manage access to the physical medium • Bridges are capable of filtering frames based on any Layer 2 fields • Bridges can be used to connect dissimilar networks, allowing communication between them. 3

Bridges 4

LAN Switches 7 6 5 4 3 2 1 • Switches provide dedicated bandwidth and high packet throughput to users and servers at low cost • Switches are designed to work with the existing cable infrastructures so they can be installed with minimal disruption to existing networks • Switches may replace shared hubs • LAN switches are a type of fast multi-port bridge designed to increase the performance of the LAN by separating collision domains and selectively forwarding traffic to the appropriate segments • LAN switches improve the performance of LANs as they create isolated collision domains • LAN switches have the benefits of increased capacity, segmentation, parallel conversations 5 and connectivity for LANs.

Switches 6