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Network Layer (IP)

Last updated May 1, 2022

Layer 3, the layer below the Transport Layer and layer above the Link Layer

  1. Unit: Packet (datagram)
  2. Responsibilities: Routes packet through routers to destination machine (not necessary if two devices are on the same network)
  3. Two main functions
    1. Forwarding: move packets from router’s input to appropriate router output (process of getting through a single interchange)
    2. Routing: determine route taken by packets from source to destination (process of planning trip from source to destination)

# Packet Definition

Contains information about the packet itself (metadata) and the body/content

# BGP Advertisement

  1. IP Addresses: the one they are advertising they can reach
  2. Gateway Next Hop: address of the entry point
  3. AS Path: Sequence of AS’s a packet would need to travel through

# Network Tiers

The structure of the internet is organized into entities called autonomous systems (ASs).

Each AS is

# Routing

Both IGP and EGP run at the application layer

# Internal Gateway Protocols (IGP)

# External Gateway Protocol (EGP)

Interactive Graph