Computer Networks

Internetworking Devices Network Interface Card (NIC) Repeaters HUB Bridge Switch Router

NIC Usually PCI Card  Plugs into Motherboard Separately designed for Ethernet, Token Ring, FDDI etc Communicate with network through Serial Connection Communicate with System with Parallel Connection Have embedded MAC/Physical Address on a chip

NIC Functionality Performs most of Layer Two functions  LLC (Logical Link Control) Interface with upper layers  MAC (Medium Access Control) Shared access to medium  Framing Packages Frames  Signaling Create Bits/Signals for transmission over Medium  Error Detection New NICs have built-in Error Detection Facility

Repeaters It boosts the signal so that it could travel a longer cable length Works at layer One (Physical Layer) Advantage  Extend cable length Disadvantage  Also propagate the noise

HUB Connects multiple nodes in a single network segment Works at Layer One (Physical Layer) Broadcasting Device Multi-port Repeater Detects and troubleshoots collisions Became Obsolete

Bridge Used for Network Segmentation at Layer two Segmentation  Dividing a big network into parts  Advantage Less Collisions More Bandwidth Makes MAC table Intelligence Device (Make Decisions)

Switch Similar to HUB but is an intelligent device Forwards Packets based upon their destination address Increase bandwidth A switch gives any device on the network the full bandwidth instead of sharing the available bandwidth.  Intelligence ensures only destination receives the data, at maximum bandwidth. Decrease collisions Direct Connection between multiple hosts

Switch Also known as Multi-port Bridge Store & Forward Device  Store & Forward Vs Cut through MAC Table Typically works on Layer 2 Layer 3 Switches are also available Advance Switches are manageable  MAC Filtering  SNMP (Simple Network Management Protocol)  VLAN Setting

Router A router is a device that forwards data packets from one network to another. Routers read the network address in order to route data via the optimum path.  Data packets which are addressed to a device at the same site of the router will not be let through. Convert data structure from one media to another, for example Ethernet ISDN. Routers can interconnect all networks in the enterprise.  For example two different networks like a LAN and the Internet

Router Also Performs Segmentation  Layer 3 Segmentation based upon IP (logical address) Performs switching as switch Best Path Selection based upon Network address Encapsulation/De-encapsulation of Packet Routing Table

Gateway Some times router may be used as a Gateway  Gateway is an essential functionality provided by router It is a node that serve as entrance to another network and vice versa Normally used between private networks and internet Any packet whose address doesn’t belong to current network is forwarded to gateway Gateway may/may not perform NAT