Please enable JavaScript.
Coggle requires JavaScript to display documents.
REDES - Coggle Diagram
REDES
ARP Functions
When a packet is sent to the data link layer to be encapsulated into an Ethernet frame, the device refers to a table in its memory to find the MAC address that is mapped to the IPv4 address.
The sending device will search its ARP table for a destination IPv4 address and a corresponding MAC address.
If the packet’s destination IPv4 address is on the same network as the source IPv4 address, the device will search the ARP table for the destination IPv4 address.
If the destination IPv4 address is on a different network than the source IPv4 address, the device will search the ARP table for the IPv4 address of the default gateway.
-
-
-
-
Introduction to ARP
Destination MAC address
The MAC address of the Ethernet NIC, which will be either the MAC address of the final destination device or the router.
-
To determine the destination MAC address, the device uses ARP. ARP provides two basic functions:
- Resolving IPv4 addresses to MAC addresses
- Maintaining a table of mappings
-
ARP Broadcasts
As a broadcast frame, an ARP request is received and processed by every device on the local network.
On a typical business network, these broadcasts would probably have minimal impact on network performance.
However, if a large number of devices were to be powered up and all start accessing network services at the same time, there could be some reduction in performance for a short period of time, as shown in the figure.
-
ARP Spoofing
In some cases, the use of ARP can lead to a potential security risk known as ARP spoofing or ARP poisoning.
The attacker sends an ARP reply with its own MAC address. The receiver of the ARP reply will add the wrong MAC address to its ARP table and send these packets to the attacker.
Enterprise level switches include mitigation techniques known as dynamic ARP inspection (DAI). DAI is beyond the scope of this course.
-
