CCNA Routing and Switching Lesson 02 - Network Devices - Eric Vanderburg

1. Network Devices
Chapter 2
Networking Essentials – Eric Vanderburg © 2005

2. Network Devices
Repeater
 Hub
 WAP (Wireless Access Point)
 Bridge
 Switch
 Router
 Brouter / Layer 3 Switch
 Gateway
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3. Repeater
Attenuation – degeneration of a signal
 Cleans up the signal
 Extends the distance of the network
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Repeaters are for digital transmissions
 Optical repeaters for fiber optics
 Amplifiers are for analog transmissions
 Layer 1 component
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4. 5-4-3 rule
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5 segments, 4 repeaters, 3 of the five
segments may contain host nodes.

5. Hub
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Central wired access point
Broadcasts all data to all other devices
(everything that goes in comes back out)
Shared medium (contention)
Layer 1 component
Passive Hub
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Does not regenerate the signal
Does not have to be powered
Active Hub
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Regenerates the signal
Must be powered
Multi-port repeater

6. WAPs (Wireless Access
Points)
Wireless clients connect through
specified channels within an
electromagnetic frequency
 Layer 1 device
 Contention
 Speeds get slower the further away you
are from the AP (Access Point)
 Other objects may cause interference
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7. Ethernet
CSMA/CD (Carrier Sense Multiple
Access Collision Detection)
 Collisions cause nodes to enter into a
backoff state where they do not transmit
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8. Bridge
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Analyzes layer 2 addresses
Makes forwarding decisions
Broadcast frames are always forwarded
Segments the collision domain
Layer 2 device
Transparent Bridge - Keeps a bridging table
for each side
Source-Routing Bridge – The source host
provides info on how to reach the destination
host. (Used on Token Ring networks)
Translation Bridges – connect two different
networks

9. Switch
Multi-port Bridge
 Layer 2 device
 Creates a bridging table for all ports
 Microsegmentation – creating a virtual
circuit between two ports.
 Each port receives the full bandwidth
 Reduces the collision domain
 Higher security against sniffers (also
harder to do network diagnostics)
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10. Routers
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Connects internetworks and diverse segments
Layer 3 device
Looks at logical addresses to make a routing
decision
Exchanges routing information with other
routers using routing protocols
Segments the broadcast domain because
broadcasts are not routed
Slower than lower network devices
Can filter packets based on ACLs (Access
Control Lists)

11. Other Devices
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Brouter / Layer 3 Switch
Works with frames for nonroutable protocols
and packets for routable protocols
 Can route between VLANs (Virtual LANs)
 Faster in some cases than a router
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Gateway
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Can translate between different protocols
suites all the way to the application layer

12. Acronyms
ACL, Access Control List
 AP, Access Point
 CSMA/CD, Carrier Sense Multiple
Access Collision Detection
 VLAN, Virtual LAN
 WAP, Wireless Access Point
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