ARP return for disconnected eth1 IP address

[hattons]

@ken_yap

Gratuitous_ARP - The Wireshark Wiki

talks about gratuitous ARP replies. Maybe hostone decided to tell everybody that it has the address 1.1.2.5 to help detect clashes (or potential clashes).

The host that is booting broadcasts this:

122	52.994209	IntelCor_59:1c:a5	Broadcast	ARP	Who has 1.1.2.5?  Tell 0.0.0.0

The responses are directed specifically to the MAC address IntelCor_59:1c:a5.

123	52.994295	Standard_5d:1a:5d	IntelCor_59:1c:a5	ARP	Gratuitous ARP for 1.1.2.5 (Reply)

124	52.994318	Standard_54:17:5d	IntelCor_59:1c:a5	ARP	Gratuitous ARP for 1.1.2.5 (Reply)

125	52.994319	Standard_5d:1e:ff	IntelCor_59:1c:a5	ARP	Gratuitous ARP for 1.1.2.5 (Reply)

I’m confused about the “Gratuitous” adjective. I get that even when the APR response comes directly from the NIC (eth1) with the requested IP address. According to the wireshark wiki, “A gratuitous ARP reply is a reply to which no request has been made.” That seems inconsistent with the situation. A request was made.

@ken_yap

Is there a reason you can’t disable eth1 on all the hosts that are inactive? This seems a better solution than physically unplugging the cable.

I inherited the configuration. The configuration is not (directly) under my control. Even if we do decide to go with that option, I still want to understand what’s going on.