Wireshark shows me this everytime with the ISR directly connected to my second ether port on my desktop:
| 242 | 50.097091000 | Heurikon_69:a1:a0 | Broadcast | ARP | 60 | Gratuitous ARP for 192.168.2.9 (Request) | Broadcast | Heurikon_69:a1:a0 |
which i looked up the Heurikon and it is part of the switch as i believe someone posted here on this site.
and the ARP info states:
hardware Type: Ethernet (1)
Protocol type: IP (0x0800)
Hardware size: 6
Protocol size: 4
Opcode: request (1)
[Is gratuitous: True]
Sender MAC address: Heurikon_69:a1:a0 (00:80:f9:69:a1:a0)
Sender IP Address: 192.168.2.9 (192.168.2.9)
Target MAC Address; Broadcast (ff:ff:ff:ff:ff:ff)
Target IP address: 192.168.2.9)