About this interactive
From the lesson:
- **Same LAN:** the host ARPs for the destination's own IP address and frames the data to that device's MAC.
- **Another network:** the host sees the IP address is outside its network and sends to its **default gateway**, usually the router at the edge of the network.
- **Finding the gateway's MAC:** the host knows the gateway's IP address, so it sends an ARP request for it. The request is broadcast; the router recognizes its own IP and replies with its MAC.
- **The frame:** source MAC is the host's, destination MAC is the router's. The packet inside still carries the far server's IP address, and the router takes it on from there.
What you'll learn
- Predict which IP address a host resolves with ARP and whose MAC address goes in the frame, for a destination on its own LAN and for one on another network
- Recognize that traffic to another network is framed to the default gateway's MAC address while the packet keeps the far server's IP address
Aligned to
Cisco CCST Networking
4.4
Explain basic routing concepts
Cisco CCNA
1.1
Explain the role and function of network components
Key terms
- Default Gateway
- The router that a device uses to send traffic to destinations outside its local network.
- Address Resolution Protocol
ARP
- A protocol used to map an IP address to a physical MAC address on a local network.
- MAC Address
- A 48-bit hardware address assigned to a network interface and written as six hexadecimal octets, such as 00:1A:2B:3C:4D:5E. It identifies a device uniquely on a local network segment, and switches forward frames by looking it up in their MAC address table.
- IP Address
- A numerical label assigned to each device connected to a network that uses the Internet Protocol.
- Router
- A network device that forwards data packets between networks based on IP addresses.
- Ethernet Frame
- The Layer 2 data unit used on Ethernet networks, containing a preamble, source and destination MAC addresses, an EtherType field identifying the Layer 3 protocol, a payload (typically an IP packet), and a 4-byte FCS for error detection. Switches use the MAC addresses in Ethernet frames to make forwarding decisions.
Topics
Default Gateway
Arp
Mac Address
Ip Address
Router
Interactive
Predict
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