LAN Switching and Wireless Basic Switch Concepts and Configuration

Objectives  Summarize the operation of Ethernet as defined for 100/1000 Mbps LANs in the IEEE standard.  Explain the functions that enable a switch to forward Ethernet frames in a LAN.  Configure a switch for operation in a network designed to support voice, video, and data transmissions.  Configure basic security on a switch that will operate in a network designed to support voice, video, and data transmissions.

Summarize the operation of Ethernet as defined for 100/1000 Mbps LANs in the IEEE standard Key elements of Ethernet/802.3 networks

Communication types reminder  Unicast – to a single host address e.g. most user traffic: http, ftp, smtp etc.  Broadcast – addressed to all hosts on the network e.g. ARP requests.  Multicast – to a group of devices e.g. routers running EIGRP, group of hosts using videoconferencing. IP addresses have first octet in range 224 – 239.

Summarize the operation of Ethernet as defined for 100/1000 Mbps LANs in the IEEE standard Design considerations for Ethernet/802.3 networks

Network Latency  NIC delay – time taken to put signals on medium from one end and to translate it on the other end.  Propagation delay – time spent travelling on medium  Latency from intermediate devices e.g. switch or router. Depends on number and type of devices. Routers add more latency than switches.

key elements of Ethernet networks  CSMA/CD (Carrier sense multi access / Collision detection): it is the IEEE standard. Carrier Sense In CSMA/CD, all devices that have messages to send must listen before transmitting. If a device detects a signal from another device, it waits before attempting to transmit. When there is no traffic detected the device starts transmitting its message. While this transmission is occurring, the device continues to listen for traffic on the LAN. After the message is sent, the device returns to its default listening mode. Multi-access If the signals of one device are not detected by a second device, the second device may also starts to transmit. The media now has two devices transmitting messages at the same time. The messages travel across the media and once they meet each other then a collision happens and the messages are destroyed. Note: CSMA/CD is only used with half-duplex communication typically found in hubs. In full-duplex mode the collision detect circuit is disabled.

key elements of Ethernet networks  Collision Detection When a device is in listening mode, it can detects a collision that might happens in the media.  Jam Signal and Random Back off When collision is detected, the transmitting devices send out a jamming signal. The jamming signal notifies other devices of a collision and that they need to back off and stop transmitting for a random amount of time.

Explain the Functions that Enable a Switch to Forward Ethernet Frames in a LAN

Configure a Switch for Operation in a Network

Cisco IOS help facilities

Configure a Switch for Operation in a Network Cisco IOS commands to access the command history

Configure a Switch for Operation in a Network

Prepare the switch to be configured

Configure a Switch for Operation in a Network The basic switch configuration console Ethernet

Configure a Switch for Operation in a Network

Configure Basic Security on a Switch

Cisco IOS commands used to disable unused ports Configure Basic Security on a Switch

Questions Describe the operation of Ethernet as defined for 100/1000 Mbps LANs in the IEEE standard. What functions enable a switch to forward Ethernet frames in a LAN? How do you configure a switch for operation in a network designed to support voice, video, and data transmissions?

Summary  LAN Design Process that explains how a LAN is to be implemented Factors to consider in LAN design include Collision domains Broadcast domains Network latency LAN segmentation

Summary  Switch forwarding methods Store & forward – used by Cisco Catalyst switches Cut through – 2 types Fast forwarding Cut through

Summary  Symmetric switching Switching is conducted between ports that have the same bandwidth  Asymmetric switching Switching is conducted between ports that have unlike bandwidth

Summary  CISCO IOS CLI includes the following features Built in help Command history/options  Switch security Password protection Use of SSH for remote access Port security