© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Growing the Network Maximizing the Benefits of Switching

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Outline Overview Microsegmentation Full-Duplex Communication The Need for Different Media Rates in an Enterprise Network Physical Redundancy in an Ethernet LAN Loop Resolution with Spanning-Tree Protocol Summary

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Microsegmentation Microsegmentation of the Network

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Half Duplex versus Full Duplex

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v The Hierarchy of Connectivity

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Enterprise LAN Ethernet Connectivity

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Loops

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Spanning-Tree Protocol

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Summary Switched LANs provide microsegmentation, which means that each device on a network segment is connected directly to a switch port and receives its own bandwidth; each device does not have to contend for bandwidth with any other device on the network. Half-duplex communication in an Ethernet LAN allows data transmission in one direction at a time only (either sending or receiving); full-duplex communication allows both sending and receiving of data simultaneously. Switches provide full- duplex communication capability.

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Summary (Cont.) Employing a hierarchy of Ethernet connectivity is usually the most effective way to provide speed where it will be most effective in a campus network, implementing Fast Ethernet and Gigabit Ethernet primarily in workgroup and backbone connections. Switches provide the valuable feature of redundancy to ensure availability of the network, but redundancy can cause loops.

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v Summary (Cont.) Loops result when switches connected to the same segment transmit the same data. The data frames circulate between the two paths without being removed from the network and may cause inaccurate data in the MAC address tables. The solution to loops is STP, which manages the paths to given network segments. STP provides path redundancy in an Ethernet LAN while preventing undesirable active loops in the network.

© 2005 Cisco Systems, Inc. All rights reserved. INTRO v