Switching WhitePaper Essay Example for Free

Switching WhitePaper EssaySource mac consultationes are well-educated from incoming frames.A table of MAC addresses and their associated ports are built and maintained. Unknown unicast, broadcast and multicast frames are make full to all ports (except the incoming port) Bridges and switches communicate with each other using spanning tree protocol to resist bridging loops. stratum 2 SwitchingA layer 2 switch practices the same functionality as a transparent bridge, however a switch is like a multiport bridge that performs hardware-based-bridging. Frames are forwarded using vary hardware, called application-specific integrated circuits (ASIC). This hardware gives shifting great scalability, with wire-speed capital punishment, depleted latency, and high port density. As long as Layer 2 switch frames between two Layer 1 interfaces of the same media type, such as two Ethernet connection or an Ethernet connection and a Fast Ethernet connection, the frames do not have to be modified. However, if two interfaces are different media, such as Ethernet and Token Ring or Ethernet and Fibre Distributed entropy Interface (FDDI), the Layer 2 switch mustiness translate the frame contents before displace out the Layer 1 interface.Layer 2 SwitchingOne draw back to Layer 2 switching is that it sewer not be scaled effectively. Switches must forward broadcast business to all ports, causing medium-large switched networks to become a large broadcast domain. In addition, STP empennage have a slow convergence time when the switch topology changes. Layer 2 switching alone can not provide an effective, scalable network design. Layer 2 SwitchesFunctionsSource MAC Address learningFiltering/ forwardingLoop avoidanceFrame Switching ModesStore and forward make love throughFast ForwardingFragment FreeLayer 3 SwitchingPackets are forwarded at Layer 3, just as a router would do. Packets are switched using specialized hardware, ASIC, for high speed and low latency. Packets c an be forwarded with security restrain and quality of service (QOS) using layer 3 address translation. Layer 3 switches are designed to examine and forward packets in high-speed LAN environments. Whereas a router might impose a bottleneck to forwarding throughput, a Layer 3 switch can be placed anywhere in the network, with little or no performance penalty.Layer 4 SwitchingPackets are forwarded using hardware switching, based on layer 3 addressing and Layer 4 application information. (Layer 2 addressing is also inherently used) Layer 4 protocol types (UDP or TCP, for example) in packet headers are examined. Layer 4 segment headers are examined to determine application port numbers. Allows finer control over movement of information.Layer 4 SwitchingA Layer 4 switch must allocate a large amount of memory to its forwarding table. Layer 2 and Layer 3 addresses have forwarding tables based on MAC and network addresses, making those tables only as large as the number of network devices. Layer 4 devices, however, must keep track of application protocols and conversations occurring in the network. Their forwarding tables become proportional to the number of devices multiplied by the numberof applications.Multilayer SwitchingPackets are forwarded in hardware that combine Layer 2, Layer 3, Layer 4 switching. Packets are forwarded at wire speed.The traditionalistic Layer 3 routing function is provided using Cisco Express Forwarding (CEF), in which a database of routes to either destination network is maintained and distributed to switching ASICs for very high forwarding performance.Multilayer SwitchingCisco switches perform multilayer switching at Layer 3 and Layer 4 The Catalyst family of switches cache traffic execute based on IP addresses. At layer 4, traffic flows are cached based on starting time and destination addresses, in addition to source and destination ports. All switching is performed in hardware, providing equal performance at both Layer 3 and Layer 4 switching.Referencehttp//www.lantronix.com/resources/net-tutor-switching.htmlhttp//www.cs.virginia.edu/cs757/slidespdf/757-01-CommNetworks.pdf