Chapter Six
Networking
Hardware
Network Interface Cards (NICs)
Connectivity devices enabling a workstation, server, printer or other node to receive and transmit data over the network media
Sometimes called network adapters NICs are physical and data link layer
devices
Network Interface Cards (NICs)
Types of NICs Industry Standard
Architecture (ISA) MicroChannel
Architecture (MCA) Extended Industry
Standard Architecture (EISA)
Peripheral Component Interconnect (PCI)
FIGURE 6-1 Four primary bus architectures
Network Interface Cards (NICs)
NICs may connect to interfaces other than a PC’s bus. For example:– For laptop computers, Personal Computer Memory
Card International Association slots may be used to connect NICs
• PCMCIA
• Also called PC card
• Developed in the early 1990s to provide a standard interface for connecting any type of device to a portable computer
Network Interface Cards (NICs)
FIGURE 6-3 Typical PCMCIA NIC
FIGURE 6-4 Parallel port NIC
Network Interface Cards (NICs)
FIGURE 6-5 Wireless NIC and transceiver
FIGURE 6-6 Ethernet NICs for printers
Network Interface Cards (NICs)
Installing NICs– Installing hardware– Configuring software
• Installing driver—software the tells OS how to communicate with NIC
• Specifying IRQ, memory range, I/O port
– Configuring firmware• Utilities supplied with NIC that enables you to write
configuration changes to the EPROM chip on the NIC card
Installing and Configuring NIC Software
After NIC is physically installed, restart the PC
The driver for the NIC card must be installed and configuration information entered
Repeaters
Connectivity device that regenerates and amplifies an analog or digital signal
FIGURE 6-14 Repeater
Hubs
Multiport repeater containing one port that connects to a network’s backbone and multiple ports that connect to a group of workstations
Hubs
Passive hubs– Only repeats signal
Active hubs– Regenerate or amplify
signal
Intelligent hubs– Possesses processing
capabilities
Standalone Hubs– Serves a workgroup of computers that are
separated from the rest of the network Stackable Hubs
– Designed to be linked with other hubs in a single telecommunications closet
Modular Hubs andIntelligent Hubs
Modular hub– Provide a number of interface options within
one chassis• Connection point for networks using with different
cabling, e.g., 10base2 and 10baseT
Intelligent hubs– Also called managed hubs– MIB (management information base)
• Collection of data used by management programs to analyze network performance
Choosing the Right Hub
Performance Cost Size and growth Security Management benefits Reliability
Bridges
Reduce network traffic bottleneck
Regenerate signals to extend network lengths
Operate at the Data Link Layer of the OSI model because they have to read packet addresses
Bridges Filtering database
– Collection of data created and used by a bridge that correlates the MAC addresses of connected workstations with their locations
– Also known as a forwarding table
Segment 1
Segment 2
Bridge
Bridges
Transparent Bridging– Method used on most Ethernet networks
Source Route Bridging– Method used on most Token Ring networks
Translation Bridging– Method that can connect Token Ring and
Ethernet networks
Switches
Switches subdivide a network into smaller logical pieces
Collision domain– Portion of a LAN
encompassing devices that may cause and detect collisions among their group
Switches are layer 2 devices
Switches
Switch Methods– Cut-through mode—switch reads only the
header to determine where to forward the packet.
– Store and forward mode—switch reads the entire packet and checks for accuracy before forwarding
Using Switches to Create VLANs
Virtual local area networks (VLANs)– Means by which a
switch can logically group a number of ports into a broadcast domain
Higher-Layer Switches
Switch capable of interpreting Layer 3 is called a Layer 3 switch
Switch capable of interpreting Layer 4 is called a Layer 4 switch
Higher-layer switches may also be called routing switches or application switches
Routers Routers connect two or
more networks Consist of hardware and
software– Hardware
• Network server, separate computer, special black box
• Physical interface for various networks
– Software • Operating system and Routing
protocol
Routers operated at the Network layer
Routers Can connect dissimilar LANs and WANs
running at different transmission speeds and using a variety of protocols
Read the network address information in a packet
Calculates the optimal path to a particular network– Reroute packets if a path is not available
Routing tables stored in the router list all known addresses and possible paths
How do Routers Select Routes
Dynamic route selection– Routers continually adjusts the routes based on
network conditions
Static route selection– Route is designated in a table and router cannot
vary from that route
Router Features and Functions
Filter out broadcast transmission to alleviate network congestion
Prevent certain types of traffic from getting to a network
Provide high network fault tolerance through redundant components
Monitor network traffic and report statistics to a MIB Diagnose internal or other connectivity problems and
trigger alarms
Routers
Routing Protocols
Means by which routers communicate with each other about network status Routing protocol characteristics
– Convergence time• The time it takes for a router to recognize a best path in the event of a change or outage
– Bandwidth overhead• Burden placed on an underlying network to support the routing protocol
Routing Protocols
RIP (Routing Information Protocol) for IP and IPX
OSPF (Open Shortest Path First) for IP– Best path refers to the most efficient route from one
node on a network to another
EIGRP (Enhanced Interior Gateway Routing Protocol) for IP, IPX, and AppleTalk
BGP (Border Gateway Protocol) for IP
Brouters and Routing Switches
Bridge router– Also called a brouter– Industry term used to describe routers that take
on some characteristics of bridges
Routing switch– Another term for a Layer 3 or Layer 4 switch
Gateways
Combination of networking hardware and software that connects two dissimilar kinds of networks– E-mail gateway
– IBM host gateway
– Internet gateway
– LAN gateway