7. The Access Layer // Flashcards
What is Ethernet?
Ethernet is NIC cards to NIC cards on the same network
What are the Ethernet Frames Fields?
- Preamble
- Start Frame Delimiter
- Destination MAC Address
- Source MAC Address
- Length Type
- Data
- Frame Check Sequence
What is Destination MAC Address in the Ethernet Frame?
This is the MAC address of the destination, on that network. This is the MAC Address of the NIC card where this Ethernet frame is going to on the network
What is Start Frame Delimiter in the Ethernet Frame?
This indicates to receiving NIC that the following this start frame delimiter will be the actual information associated with the ethernet frame
What is Source MAC Address in the Ethernet Frame?
This is the MAC Address of the originated of the Ethernet Frame
What is Preamble in the Ethernet Frame?
This is used to just get the receiving NIC in sync with the bits that are coming down the cable
What is Frame Check Sequence in the Ethernet Frame?
This is the error checking, ensuring that there are no errors in the whole ethernet frame along the way
What is Length Type in the Ethernet Frame?
This can be the length of the data or the payload, or how many bytes or in the data, or it can be type field such as “what type of data is this” (is this an IPv4 packet, is this an IPv6 Packet)
What is Data in the Ethernet Frame?
This is the encapsulated data that can be IPv4 or IPv6, along with its protocols.
What layer does the Ethernet Switches operate?
Layer 2 - Data-Link Layer
What is in the Switch?
Mac Address Table
How will the switch deliver the Ethernet Frame from NIC?
It will look for the Source and destination MAC Address and deliver it.
How does the switch builds it table? Explain
1st Case: When a switch receives an Ethernet frame, it will look on the Source MAC Address of that NIC and also on what port it came from like if it is on Fast Ethernet Port 01. If the switch detects that the Ethernet Frame is new, it will add its Source MAC Address Ethernet Port 01 Table.
Now after the switch learned about the Source MAC Address, it will identify what is the Destination MAC Address. If it is not on the table of the switch, then it will known as the “Unknown Unicast” then it will send it to all the ports except the source port. The only matching Destination MAC Address on the NIC Card will receive it.
From that, all of the MAC Address is being built up from receiving MAC Address and passing it.
The Switch will keep the MAC Address for just about 5 minutes.
