The document discusses collision and broadcast domains in Ethernet networking. It defines a collision domain as a set of devices that could experience frame collisions and a broadcast domain as a set of NICs that will receive broadcast frames from one another. It describes Ethernet implementations like 10Base2, 10Base5, 10BaseT with hubs and switches. Hubs create a single collision domain while switches create multiple collision domains with full-duplex ports. The document also covers Ethernet addressing, framing, cabling, encapsulation, and LAN design models.

1. IST 228Ch1Internetworking 1
Collision/Broadcast Domain
• The term collision domain defines the set of
devices for which their frames could collide
• A broadcast domain is a set of NICs for which a
broadcast frame sent by one NIC will be received
by all other NICs in the broadcast domain.
• Hub?
• Bridge?
• Switches?
• Routers?

2. IST 228Ch1Internetworking 2
Identify collision and broadcast domains for each case

3. IST 228Ch1Internetworking 3
10-Mbps Ethernet
• No hub, switch, or wiring panel. The series of cables
creates an electrical bus
• the carrier sense multiple access collision detect
(CSMA/CD)
• 10Base2: 10Mbps, baseband technology, almost 200
meters
• 10Base5: 10Mbps, baseband technology, almost 5 00
meters

4. IST 228Ch1Internetworking 4
Ethernet Networking with a Hub
Half-Duplex 10BaseT
1. The network interface card
(NIC) sends a frame.
2. The NIC loops the sent frame
onto its receive pair.
3. The hub receives the frame.
4. The hub sends the frame
across an internal bus so that
all other NICs can receive the
electrical signal.
5. The hub repeats the signal to
each receive pair to all other
devices.

5. IST 228Ch1Internetworking 5
Ethernet Networking with a Switch
Full Duplex Ethernet
• Full-duplex means that an
Ethernet card can send
and receive concurrently.
• Use a switch or direct
connection from host to
using a crossover cable.
• The switch interprets the
electrical signal as an
Ethernet frame and
processes the frame to
make a decision.
• Hub – Layer 1
• Switch – Layer 2

6. IST 228Ch1Internetworking 6
Basic Ethernet Features
10Base2, 10Base5 Single bus cabled serially between devices using coaxial
cable.
10BaseT with a Hub One electrical bus shared among all devices creating a single
collision domain, cabled in a star topology using twisted-pair
cabling
10BaseT with a Switch One electrical bus per switch port creating multiple collision
domains, cabled in a star topology using twisted-pair cabling
Half Duplex Logic that requires a card to only send or receive at a single
point in time. Used to avoid collisions
Full Duplex Logic that enables concurrent sending and receiving, allowed
when one device is attached to a switch port, ensuring that
no collisions can occur.

7. IST 228Ch1Internetworking 7
Ethernet Addressing
• Ethernet uses MAC address burned into
each NIC.
• 48 bits (6 bytes)
• First 3 bytes assigned by IEEE
• Unicast MAC Address
• Broadcast MAC Address (FFFF.FFFF.FFFF)
• Multicast Address

8. IST 228Ch1Internetworking 8
Ethernet Frames
• Framing defines how
a string of binary
numbers is
interpreted
• Preamble
• SD: Start frame eliminator
• Destination MAC address
– Unicast
– Broadcast
– Multicast
• Source address
• Length of file
• DSAP SSAP, SNAP (Subnet Network Access Protocol)
• Control/Data
• Frame Check Sequence (FCS)

9. IST 228Ch1Internetworking 9
Ethernet Cabling
Straight-Through Cable
• Host to Switch or hub
• Router to Switch or hub
Crossover Cable
• Switch to Switch
• Hub to Hub
• Host to Host
Rolled Cable
• Serial Port

10. IST 228Ch1Internetworking 10
Data Encapsulation
• Step 1: Data Conversion
• Step 2: Data segmentation
Hello! &@$
Application
Presentation
Session
hello 101010011100100100100
PDU1
101010011100100100100
PDU1
PDU2
101010011100100100100
PDU1
PDU2
PDU3
Transport
Name: Data Stream
0101010
0100100
PDU1
PDU2
PDU3
PDU1
PDU2
PDU3
TCP
TCP
: : Name: Segment

11. IST 228Ch1Internetworking 11
• Step 3: Packet creation for routing
• Step 4: Frame Header
• Step 5: Transmission
10010100001
Network
Name: Packet or Datagram
0101010
0100100
PDU1
PDU2
PDU3
PDU1
PDU2
PDU3
TCP
TCP
: :
Name: Frame
IP
IP
Data Link
0101010
PDU1
PDU2
PDU3
TCP
IP
LLC
MAC
LLC 802.2
MAC 802.3
FCS
Physical
Layer

12. IST 228Ch1Internetworking 12
LAN Design Models
• Mesh design
• Hierarchical design
– Three-layer network
model
– Two-layer network
model
– One-layer network
model

13. IST 228Ch1Internetworking 13
Three Layer Model
• Core-layer
• Distribution Layer
– a backbone network
connecting all LANs
– no end user at this
level
– implementation of
security and network
policies
• Access Layer

14. IST 228Ch1Internetworking 14
Two and One-Layer Model