Network Devices

1
Network Devices

• LESSON GOALS
• MAC address
• Identify Connectivity Devices their Functions
• NICs ,Transceiver
• Repeater / Hubs
• Bridges / Switches
• Routers
• Collision Broadcast Domains
• Define 5-4-3 Rule

2
MAC addresses
Harry
Sally
Lets assume that Harry wants to send information
to Sally.
If we just connect a cable (Physical Layer)
between the two computers Harrys software can
simply push the information into the cable, and
it will inevitably end up at the right place.
.
3
On a real network, such as Ethernet, Harry and
Sally are not the only users of the physical
layer.

• There must be an addressing system, a way of
  uniquely identifying computers and interfaces.

4
Media Access Control Address unique identifier
for each networking device Burned into ROM on
the NIC
5
The IEEE assigns the first 24 bits of the address
to represent the device manufacturer.
Assigned by IEEE
Organizational Unique Identifier (OUI)
2
0
0
0
4
3
D
7
1
5
E
4
The manufacturer is responsible for uniquely
assigning the remaining 24 bits to the device
Assigned by manufacturer
Representing these addresses in binary is a bit
tedious, so we convert the 48 bit address into
12 hexadecimal digits.
6
Now, we have the ability to uniquely identify
each device on the network.
7
Network Devices

• NIC Network Interface Card
• aka Network card, network adapter, Ethernet card
• serves as a go-between for the PC and the network
• can be integrated onto motherboard
• OR PCI expansion card
• OR USB or Firewire external connection

8
Network Devices

• Transceivers device that both sends data and
  receives data.
• older transceivers were external boxes
• now transceiver is built into NIC
• Premise Wiring network cables, connectors AND
  connection points
• drop cable from network to PC or other
  device(both the cable that goes from wall to PC
  AND the cable inside the wall to the patch panel)
• patch panel termination and connection point
  for all drop cables.
• patch cable from patch panel (wall) to
  connectivity device

9
Network Devices

• Repeater used to amplify a signal so that it
  can exceed maximum distance on media.
• only two ports in out
• Hub a multiport repeater- also amplifies signal
• Delivers signal to ALL devices on hub
• Active Hub also filters noise
• Passive Hub doesnt amplify just used as a
  central connectivity device
• Intelligent / Managed Hub has software for
  advanced configuration
• Switching Hub directs signal only to correct
  device

These are considered dumb devices because they
just move the signal along
10
Network Devices

• Bridge divides a bus network into segmentsi.e.
  separate networks
• only two ports in out
• Switch a multiport bridge
• Amplifies signal
• directs signal only to correct device using MAC
  address

SMART
11
Broadcast Collision Domain

• Collision Domain

Collision Domain
12
Connectivity Domains

• Collision Domain a group of network devices
  that are connected in a shared environment and
  compete for access on the same network.
• Broadcast DomainA grouping of collision domains
• When a node needs to communicate with all hosts
  on the network, it sends out a broadcast signal
  with a destination MAC address 0xFFFFFFFFFFFF
• The network interface card (NIC) of every
  physically connected host must respond
• Hubs communicate by broadcast

13
4 Repeater Rule

• No more than 4 repeaters between any two
  computers on a network.
• Why?
• Latency The delay between the time a frame
  leaves the source device and the time the frame
  reaches its destination
• Late collisions when a collision happens after
  the first 64 bytes of the frame are transmitted.
  Result of latency.
• Collision situation than can occur when 2 bits
  propagate at the same time on the same network.

14
5 4 3 Rule

• 5 segments
• 4 repeaters
• 3 segments with hosts
• 2 segments connection only
• 1 collision domain
• To exceed this, you need a switch, bridge or
  router.

15
Network Devices

• Router
• Amplifies signal
• Directs signal only to correct device usingIP
  address
• Can direct signal between LANs
• Can connect different network topologies, such as
  Ethernet and Token Ring

16

• Hub sends the message to everybody
• one big collision domain
• like yelling
• Switch sends the message only to the
  destination device in the LAN
• microsegments each port into its own collision
  domain.
• like local call
• Router sends the message only to the
  destination device in the LAN or in the WAN
• knows how to get out of LAN
• segments the collision domain AND the broadcast
  domain
• like long-distance call

17
Segmentation

• Bridges break a large segment into parts and
  create isolated collision domains.
• Bridge will divide a collision domain but has no
  effect on a broadcast domain
• Segmenting creates more collision domains
• What address does a bridge read?
• What do you call the MAC address that is made up
  of all binary 1s?
• What is the hexadecimal equivalent of11111111
  11111111 11111111 11111111 11111111 11111111

MAC address
Broadcast address
FFFFFFFFFFFF
18
Network Devices

• Half Duplex Mode
• Signal is delivered in only one direction at a
  time
• Default setting for NICs and Network devices
• Full Duplex Mode
• Signal is delivered in both directions
  simultaneously
• What happens to bandwidth when using full-duplex?
  Effectively doubles bandwidth
• What happens to collision domains when using
  full-duplex? Effectively gone.