Switches in Networking B. Konkoth

Network Traffic  Scalability  Ability to handle growing amount of work  Capability of a system to increase performance  Latency  Amount of time it takes for a packet of data to get from one designated point to another  Network failure  Failure of a component of a network because of malfunction or natural or human-caused error  Collisions  Two devices on the same Ethernet network attempting to transmit data at exactly the same time.

3 Switches  A switch is a combination of a hub and a bridge.  It can interconnect two or more workstations, but like a bridge, it observes traffic flow and learns.  When a frame arrives at a switch, the switch examines the destination address and forwards the frame to the necessary connection.

4 Switches:  Isolating traffic patterns and providing multiple access.  Switches are easy to install and have components that are hot-swappable.  The backplane of a switch is fast enough to support multiple data transfers at one time. Major role

5 Workstations connected to a shared segment of a LAN

6 Workstations connected to a dedicated segment of a LAN

7 A Switch with Two Servers Allowing Simultaneous Access to Each Server

8 A server with two NICs and two connections to a switch

9 A pair of remote bridges and switch combination designed to isolate network traffic

10 Switch providing multiple access to an server

Switches vs Routers SwitchesRouters  Switches are considered layer-two devices  Uses MAC address  Faster  Switches are used within networks to forward local traffic intelligently  Routers are layer-three devices  Uses IP address  Because of the additional processing required have high latency  Routers are used between networks to route packets in the most efficient manner

Fully switched network  Switches replace all the hubs of an Ethernet network with a dedicated segment for every node  Since any segment contains only a single node, the frame only reaches the intended recipient  This allows many conversations to occur simultaneously

Full Duplex vs Half Duplex Full Duplex Half Duplex  A data communications term that refers to the ability to send and receive data at the same time  Information can move in only one direction at a time

14 Full duplex connection of workstations to a LAN switch

Network Segment  A network segment is a single span of physical connectivity between two computer devices  Also used to describe a group of computer equipment organized as a network using the same range of addresses

Network Segment

Cut-through switch  A packet switch where the switch starts forwarding that frame (or packet) before the whole frame has been received, normally as soon as the destination address is processed.  This technique reduces latency through the switch, but decreases reliability

Store and forward switch  Switch will save the entire packet to the buffer and check it for errors or other problems before sending  If the packet has an error, it is discarded.

Fragment-free switch  It works like cut-through except that it stores the first 64 bytes of the packet before sending it on.  The reason for this is that most errors, and all collisions, occur during the initial 64 bytes of a packet.