A beginner question: Why we need to assign IP addresses on LAN if switches are not able to read them? Because of ARP (Address Resolution Protocol)? But Switches can't send ARP requests (switches can't read ipv ), right? Who sends the ARP request then?

  • 3
    Fortunately the internet isn't a massive switched LAN. Routers break up the internet into managable layer2 chunks; routers need IP and ARP, which is why your computers need IP addresses as well. – This May 20 '14 at 12:20
  • DO you mean why you have to assign an IP address to an ethernet switch ? (since "assign IP addresses on LAN" isn't a sentence that makes sense) – nos May 20 '14 at 18:33

An IP address on a true layer 2 only switch is used for management (accessing the CLI remotely, sending SNMP traps, logging, TACACS/RADIUS, etc.). The IP address on the switch is in no way required for the switch to actually do its job, which is to switch frames.


If i read your question as "why do I have to assign IP addresses to my clients" the answer is: You don't have to. There are other protocols then IP (I guess you mean IPv4 because you are mentioning ARP). You can use IPv6, IPX, Appletalk, ...

You need some protocol on Layer-3 (like IPv4, IPv6, IPX, ...) so that your hosts can talk to each other and to other parts of the network.

As mentioned by others: On a Layer-2 switch IPv4 is only used for management. A pure Layer-2 switch should not care about protocols above layer-2 for switching packets.

As a side note: There where / are some older chips used in switches which can't do Ethernet multicast and can't be used in (most) IPv6 environments.

  • It's pretty crazy to lead with the notion that he doesn't need IP, since the question includes ARP. IPv6 uses Neighbor Solicitation instead of ARP – user5025 May 20 '14 at 21:24
  • 2
    The question may include ARP but that is question inside the question. Better read the original question again. – Jens Link May 23 '14 at 23:23

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