Link/ Data Link Flashcards
What are protocols at the link/data link layer primarily concerned with?
The protocols operating at this layer are primarily concerned with the identification of devices on the physical network and moving data over the physical network between the devices that comprise it, such as hosts (e.g. computers), switches, and routers.
What is the most common protocol at the link/ data link layer?
The most commonly used protocol at this layer is the Ethernet protocol.
What is the PDU at the link/ data link layer? What do they encapsulate?
Ethernet Frames are the Protocol Data Unit, and they encapsulate data from the Internet/ Network layer above.
What do Ethernet frames do?
An Ethernet Frame adds logical structure to the binary data that flows on the physical network. The ethernet protocol structure defines which bits are actually the data payload, and which are metadata to be used in the process of transporting the frame.
How does a device know what parts of an ethernet frame are which?
An Ethernet-compliant network device is able to identify the different parts of a frame due to the fact that different ‘fields’ of data have specific lengths in bytes and appear in a set order.
What is an interframe Gap?
This gap is a brief pause between the transmission of each frame, which permits the receiver to prepare to receive the next frame.
What are the parts of an ethernet frame?
Frame header (including source and destination MAC addresses, data payload, and optional trailer/footer.
What is a MAC Address?
Also called the physical addressorburned-in address the mac address is assigned to every network enabled device when it is manufactured.
What form does a MAC address take?`
as a sequence of six two-digit hexadecimal numbers, e.g.00:40:96:9d:68:0a
What the difference between a hub and a switch?
A hub sends traffic to every device connected to it, a switch maintains a table of the MAC addresses of each device connected to it and only send the frame to the right device.
Why doesn’t MAC addressing work for large networks?
- They are physical rather than logical. Each MAC Address is tied (burned in) to a specific physical device
- They are flat rather than hierarchical. The entire address is a single sequence of values and can’t be broken down into sub-divisions.
- Thus, routing devices would need a record of each single address that existed somewhere in the world; that would mean storing impossibly large tables.
