Chapter Overview
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Network devices
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Hubs
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Broadcast
For star topology
Same as a repeater
Operate at the physical layer
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Modems
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Short for Modulator/Demodulator
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Phone (POTS – plain old telephone service)
DSL (Digital Subscriber Line)
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Digital to analog then to digital
Allow network signals to pass over phone lines
Cable
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Network Interface Card (NIC)
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Supports a protocol
Convert parallel digitals signal to serial analog
signal and serial analog signal to parallel digital
signals
Mostly built in now
Has LEDs to show if the line is live and transmitting
data
Transceiver – converting signals from, say
100Base0TX to 100Base0FX
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An (Old) Combination Ethernet NIC
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A BNC Connector with a T Attached
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An Ethernet NIC with an RJ-45 Jack
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Bridge
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Connect similar network segment together
Break collision domains
Designed for the bus topology
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Switch
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Point to point communication
Segment the message in Switch-hub setting –
function like a bridge
Know MAC address
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Wireless Access Point (AP)
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Support 802.11a/b/g/n
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Understanding Routing
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A router is a system connected to two or more
networks that forwards packets from one network to
another.
Routers operate at the network layer, sometimes
referred as layer 3, of the Open Systems
Interconnection (OSI) reference model.
Routers can connect networks running different datalink layer protocols and different network media.
Large internetworks often have redundant routers,
providing multiple routes to a destination.
Routers select the most efficient route to each
destination.
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Redundant Routers
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Router Products
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The Microsoft Windows 2000~2012, Microsoft
Windows NT, and Novell NetWare operating
systems include routing capability.
A stand-alone router is a hardware device that is
essentially a special-purpose computer (with CPU,
RAM, HD, and NICs).
More in later chapters
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Firewall
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Can be software or hardware
It separates Intranet from Internet
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DHCP
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Addresses the shortcomings of RARP and
BOOTP (two other protocols)
Dynamically allocates IP addresses from a
pool
Reclaims unused addresses
Prevents IP address duplication
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DHCP Address Allocation Types
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Manual allocation
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Automatic allocation
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Static IP address, DHCP is only good for lookups
Same IP address, assigned by DHCP server
Dynamic allocation
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(Next page)
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Dynamic Allocation
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The DHCP server leases to the client an IP
address chosen from a pool.
The client must periodically renew the lease
address.
Unrenewed lease addresses are returned to
the pool.
Dynamic allocation allows you to add,
remove, and relocate computers.
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The IP Address Leasing Process
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The address assignment process is the same for all of
the allocation methods.
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Clients using manual or automatic allocation receive no
further communication after the address assignment.
Clients using dynamic allocation lease IP addresses for
a time interval specified by the server.
The client must renew the lease on a regular basis to
continue using it.
DHCP address leases are typically measured in days.
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If addresses are in short supply, a shorter lease
interval is warranted.
If computers are rarely moved to other subnets, longer
lease intervals reduce the DHCP traffic.
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Others
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Multilayer Switch – level 3 switch
Content Switch/Web Switch
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Intrusion Detection or Prevention System
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Really?
Firmware version of software
Load Balancer
DNS Server (Domain Name Service)
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Operate at even higher level than 3
Rout to different web server based on requesting content
Convert IP address to domain name back
Proxy Server
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Useful URL
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http://www.tcpipguide.com/free/
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