Layer 3

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What Does Layer 3 Mean?

Layer 3 refers to the third layer of the Open Systems Interconnection (OSI) Model, which is the network layer.

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Layer 3 is responsible for all packet forwarding between intermediate routers, as opposed to Layer 2 (the data link layer), which is responsible for media access control and flow control, as well as error checking of Layer 1 processes.

Techopedia Explains Layer 3

Layer 3 provides the network’s routing and switching technologies that create logical paths known as virtual circuits (VC), which are used for the transmission of data between network nodes. The main functions of Layer 3 include routing and forwarding, as well as internetworking, addressing, packet sequencing, congestion control and further error handling.

The protocols used in Layer 3 include:

  • Internet Protocols IPv4/v6
  • Internet Control Message Protocol (ICMP)
  • Distance Vector Multicast Routing Protocol (DVMRP)
  • Internet Group Management Protocol (IGMP)
  • Address Resolution Protocol (ARP)
  • Internet Protocol Security (IPsec)
  • Routing Information Protocol (RIP)
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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.