ARP detect, specifically in the context described, refers to a mechanism used by a router to monitor the connection status of its Wide Area Network (WAN) interface, whether it's using a Static IP or Dynamic IP. It actively checks for the availability of the gateway by sending ARP requests and monitoring for responses.
Here's a breakdown:
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Function: ARP detect is a feature implemented in routers to determine if the WAN connection is active and reachable.
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Mechanism:
- The router periodically sends ARP (Address Resolution Protocol) requests to the gateway (the next-hop IP address for traffic going to the internet).
- The router expects to receive an ARP reply from the gateway in response to these requests.
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Purpose: The main goal of ARP detect is to detect a loss of connectivity to the gateway and take appropriate action, such as re-establishing the connection or alerting the user.
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Parameters (Based on the reference):
- ARP Request Interval: The router sends an ARP request to the gateway every 5 seconds.
- Timeout: If the router doesn't receive a response from the gateway within 30 seconds (6 failed ARP requests at 5-second intervals), it considers the WAN interface disconnected.
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Significance: This mechanism is important for maintaining a stable and reliable internet connection. Without ARP detect, the router might continue to route traffic to a gateway that is no longer available, resulting in connection failures.
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Example Scenario: Imagine your internet connection goes down because your ISP is experiencing an outage. Without ARP detect, your router might still think it has a connection and continue trying to send data through the unavailable gateway. With ARP detect enabled, the router quickly realizes the gateway is unresponsive and can initiate a reconnection attempt, or notify you of the issue.
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How it works: When a device (in this case, the router) needs to communicate with another device on the same network but only knows the IP address, it uses ARP to find the corresponding MAC address. The router broadcasts an ARP request asking, "Who has this IP address?" The device with that IP address responds with its MAC address. The router can then use this MAC address to send data directly to the gateway. If it doesn't get a reply, it assumes something is wrong.
In summary, ARP detect is a vital feature in routers that ensures the WAN interface is actively monitored by regularly probing the gateway with ARP requests, thereby enhancing the reliability of internet connectivity.
