Ethernet and Switching Flashcards
Switches
Typically used to connect all device in a network together
CSMA/CD
Carrier Sense Multiple Access with Collision Detection
Carrier Sense (listen to the wire)
Multiple Access (numerous devices)
Collision detection (Stop listening if there is a collision signal: More than 5 volts)
Collision Domain
A group of network devices that will simultaneously detect a voltage spike.
Half duplex connection between a pc and a switch
Modern collision domains used full duplex.
Duplex and Speed
Half or full duplex
Half:
One device communicates at a time (eg. walkie talkie). Used in Collision Domain.
Full:
Two devices communicate at same time (eg. phone). No collisions.
Ethernet Speed
Ethernet: 10Mbps
FastEthernet: 100Mbps
GigabitEthernet: 1Gbps
10GigabitEthernet: 10Gbps
40GigabitEthernet: 40Gbps
GigabitEhernet all require full duplex
Ethernet 2 Frame
Nothing more than a chunk of data, with a data link layer header
Consists out of 5 parts
- Destination MAC Address: 48 bits
- Source MAC Address: 48 bits
- Type: 16 bits
- Data (Packet): MAX 1500 bytes
- FCS (Frame Check Sequence): 32 bits
Destination Mac Address
Tied to the network card on device, configured at the factory.
two parts
Manufacturer ID: 24 bits
Serial Number:24 bits
Frame Check Sequence (FCS)
Performs a Cyclical Redundancy Check (CRC)
The receiver checks if the FCS value of the sent frame is the same as the FCS value of the received frame.
Protocol Data Unit (PDU)
The entire Frame including the data that is being transferred
Protocol Data Unit (PDU)
The entire Frame including the data that is being transferred
3 Typologies
Bus typology (single wire): very rarely used today
- uses 10BAse5 and 10Base2 cabling
- uses BNC connectors
Ring typology: very rarely used today
- used a Token to carry messages
- used a IBM Token Ring MAU
Star typology: most common
- uses a hub (layer 1 device) like the cisco catalyst switch
Switch
Break up collision domains
Keep track of MAC Addresses with a MAC address Table
Reads the frame-headers to find source MAC address and then populates the MAC Address Table with source addresses associated with specific ports
When the switch receives a frame it looks at the destination Mac Address and compares it to the MAC Address Table to find the port number, the message is then forwarded to the device on that port, and none of the other devices hear the conversation.
Broadcast
All F’s in the destination MAC address
FFFF FFFF FFFF (layer 2 broadcast address)
Switch will broadcast frame to all devices on the network
Broadcast Domain
Group of networked devices which will receive a layer 2 broadcast message
How to find information about network adaptor or ethernet card?
ipconfig /all
