Port Forwarding Issue

CrimpOn
Guru
Dec 21, 2023
I have never seen documentation explaining how the system detects a device connected to a specific Ethernet port. My suspicion is that the router uses Address Resolution Protocol (ARP) to determine the MAC address of a specific IP address and then pulls the connection information from internal MAC tables.

Is there a method you can use to determine if this computer is responding to ARP requests? I would connect a laptop computer to another Ethernet port on the same Orbi unit that the computer is connected to and attempt to ping the computer by IP address. What should happen is:

The laptop recognizes that the target is on the same LAN as the laptop (because of the subnet mask)

The laptop looks in its ARP table to find the MAC address to send ICMP requests (ping) to.

Oops, this IP is not in the ARP table, so use ARP to discover the MAC address.

The computer responds to ARP with "That IP belongs to ME at this MAC address"

The computer sends ICMP messages to that MAC address.

By being connected to the same Ethernet module, the only part of this traffic that leaves the module is the original ARP request (because it is a broadcast packet) and the ARP response (also a broadcast) The ICMP messages will go from one port in the module to the other port in the module. The responses also will not leave the Ethernet module.
- Tmatz
  Aspirant
  Dec 21, 2023
  So \I want to clarify. I am not trying to verify the device is connected to a specific port on the Satellite. I am trying to port forward to the computer.
  
  The computer is not showing up on the attached devices list no matter which port it is connected to, but IS getting an internet signal. I am able to connect to the internet and the device picks up that there is a 2500 Mbps connection. I am also able to ping the device on the internal network using the static IP. There is another device hardwired to the same satellite and it shows up on the attached devices list. Also I have connected the computer to the router itself and it still doesnt show up.
  
  The router is not port forwarding to the computer currently. The computer has a static IP and in the port forwarding table i identified the static IP that i want it to forward the data to. Not sure what I can do to verifiy if the ports are actually being forwarded to the device.
  - CrimpOn
    Guru
    Dec 21, 2023
    I, also, was not clear. Nothing will show which specific port any device has connected to, only whether the device is 'wired' or WiFi.
    
    There have been a number of forum posts recently regarding wired devices and the 960 product. Part of the discussion seems to focus on that 2.5G Ethernet port that is a prominent feature of the 960 products. For decades consumer routers have included 4-port Ethernet modules that are self-contained electronic devices. With the 960, Netgear seems to have abandoned that 4-port gigabit module in favor of a 3-port gigabit module plus a stand-alone 2.5G Ethernet port. (Maybe there wasn't physical space to add the 2.5G port, so "something had to go".)
    
    Is it correct to assume that when this PC:
    
    Is connected to the 2.5G port it reports 2.5G connection, and when
    
    Connected to a gigabit port it reports 1G connection?
    
    Since it (a) responds to ping and (b) has internet service, then my question about ARP is resolved.
    
    When connected to a regular gigabit port, how long do you give the Attached Devices to display it? I have found that on my old Orbi, Attached Devices can take five minutes or more to recognize a change in connection type, and I often have to "Refresh" the Attached Devices screen to get it to update.

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