12.4 Summary of Session 12
In this session you have looked at how both routers and switches make their forwarding decisions based on their relevant addresses, and how MAC addresses are learned from an IP address via the ARP process.
In this session you have met the following terms.
ARP (address resolution protocol)
A protocol used to find the MAC address of an unknown device on the local network, if you know its IP address.
The broadcast MAC address of FF:FF:FF:FF:FF:FF which will be received by all devices on the local network.
The reply data which the device sends back to the source giving its MAC address.
A data table used to temporarily store the IP address to MAC address pairings.
In this context, a type of traffic which is designed to be seen by all devices on the local network, not just a single device.
destination IP address
The IP address of the destination device (where the traffic is heading to).
destination MAC address
The MAC address of the destination device (where the traffic is heading to).
A block of information put at the start of a frame containing information such as the source and destination MAC addresses and other fields.
ICMP (Internet Control Message Protocol)
A protocol used to report network problems that prevent the delivery of IP packets. Both ping and traceroute use ICMP.
The basic unit of data at the Internet layer of the TCP/IP protocol suite.
MAC address table
Also known as ‘forwarding table’. Table used by a switch to associate MAC addresses of devices with port numbers to enable frames to be forwarded to their destination.
PDU (protocol data unit)
The term used to describe the data at each layer of the network model.
source IP address
The IP address the traffic originated from.
source MAC address
The MAC address the traffic originated from.
TCP/IP Internet layer
The layer of the TCP/IP model containing the IP address information.
TCP/IP Network Access layer
The bottom layer of the TCP/IP network model. This is where the hardware sits, along with MAC addresses.