Wireshark-users: [Wireshark-users] [wirshark-users]missing packet in promiscuous capture mode

From: "Bob Brusa" <bob.brusa@xxxxxxxxx>
Date: Tue, 22 Sep 2009 18:45:04 +0200

Hi

I am debugging the DHCP implementation of an embedded board. It should receive its address from a ZyXEL P-661HW-D3 ADSL router. Using wireshark, I can see that my board starts the DHCP-process, but I can not see any answer of the ZyXEL to my boards requests. The funny thing however is, that the debugging output of my board reports receipt of such an answer - only to drop it because it claims a checksum error. This explains why the DHCP process is not successful, but it does not explain why I do not see this packet on wireshark. I have used filters of various kind - including inspection by eye, packet for packet. This packet the board reports is not in the list of captured packet of wireshark.

The topology of my LAN is as follows:

Zyxel___Planet switch___Planet switch ____ myboard
        FSD 1600        FSD 800      |____PC #1 running wireshark
                                     |____JTAG debugger
                                     |____PC #2

Does the switch play a dirty trick? Unlikely, because I see the packets from my board and all those other packets going to/from the PC and JTAG debugger. And the DHCP-process for the two PCs was successful. Thanks for advice.

  Robert