Esteban Herlein

Addicted to discovering, learning and understanding technologies.

1 minute read

The data link layer or layer 2 is the second layer of the OSI seven-layer model of computer networks.

This layer transfers data between adjacent network nodes on a wide area network (WAN) or between nodes on the same local area network (LAN).

The data link layer provides the functional and procedural means to transfer data between network entities and could provide the means to detect and possibly correct errors that may occur at the physical layer.

The data link layer deals with the local delivery of frames between devices on the same LAN. Data link frames, as these protocol data units are called, do not cross the boundaries of a local network.

Internetwork routing and global addressing are upper layer functions, allowing data link protocols to focus on local delivery, routing, and media arbitration.

In this way, the data link layer is analogous to a neighborhood traffic police; endeavors to arbitrate between competing parties for access to a medium, regardless of its final destination.

When devices try to use a medium simultaneously, image collisions occur. Data link protocols specify how devices detect and recover from such collisions, and can provide mechanisms to reduce or prevent them.

Services

  • Encapsulation
  • Frame synchronization
  • Logical link control (Error & Flow control)
  • Media access control (MAC, LAN switching, Physical addressing, QaS, VLAN, ...)

Protocols

  • ARP Address Resolution Protocol
  • CDP Cisco Discovery Protocol
  • CAN Controller Area Network
  • Ethernet
  • EAPS Ethernet Automatic Protection Switching
  • FDDI Fiber Distributed Data Interface
  • Frame Relay
  • HDLC High-Level Data Link Control
  • IEEE 802.2 provides LLC functions to IEEE 802 MAC layers
  • IEEE 802.11 wireless LAN
  • LAPD Link Access Procedures, D channel
  • LLDP Link Layer Discovery Protocol
  • MPLS Multiprotocol Label Switching
  • NDP Nortel Discovery Protocol
  • SDN OpenFlow
  • PPP Point-to-Point Protocol
  • SLIP Serial Line Internet Protocol (obsolete)
  • SMLT Split multi-link trunking
  • IEEE 802.1aq Shortest Path Bridging
  • UDLD Unidirectional Link Detection

You May Also Enjoy

Arrangement

5 minute read

Equipped with the subject matter for your argument or speech, after having determined the issue at hand, thought out appropriate supporting arguments drawn f...

Sources of proof

4 minute read

Know the areas where you must hunt for, and track down what you are trying to find. Once you have surrounded the entire place with the nets of your though...

On persuasive speech: Marcus Tullius Cicero

4 minute read

The nature of eloquent and persuasive speech has been fiercely debated. Is rhetoric an art or a skill? Does it require natural ability, or can it be aquired ...

The next best thing

less than 1 minute read

“You do what you can for as long as you can, and when you finally can’t, you do the next best thing. You back up but you don’t give up.”