On 11/17/2010 12:57 PM, Luigi Rizzi wrote: > Hello, > > I'm facing a strange behave on the ARP answers from my TQM885D module > (U-boot 1.3.0-rc2 and kernel 2.4.25). > When I connect both Ethernet interfaces, for example configured as follow: > > Eth1: IP 192.168.0.126 MAC 00:23:DE:CC:12:01 > Eth2: IP 192.168.11.126 MAC 00:23:DE:CC:12:02 > > If an ARP request arrives from the net the module sends two answers (from the > two interfaces) with the same IP and different MACs.
I hope you connect the two interfaces to two different physical networks and the netmask is not set to 192.168.0.0/16. > > Here the packets I can see on the Ethernet sniffer: > > Source Destination Protocol Info > ------------------------------------------------------------------------------------------------------------------------------------------------ > CompaqHp Broadcast ARP Who has > 192.168.0.126? > 00:23:DE:CC:12:01 CompaqHp ARP 192.168.0.126 is at > 00:23:DE:CC:12:01 > 00:23:DE:CC:12:02 CompaqHp ARP 192.168.0.126 is at > 00:23:DE:CC:12:02 If both ethernets are connected to the same segment (that is forbidden, even if in many cases works), both ethernet controller gets the ARP broadcast request and pass the request to the upper layer. I do not know if then there is still a further check (consider that the request is broadcast, so not bound to a specific MAC), but anyway it seems to me your test is broken. However, if the two networks are not connected together, I agree there is no reason to get two answers. > Anyone can tell me the reason why I'm getting also the second answer (of > course a wrong answer) ? Maybe wrong test case... Best regards, Stefano Babic -- ===================================================================== DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-0 Fax: +49-8142-66989-80 Email: [email protected] ===================================================================== _______________________________________________ eldk mailing list [email protected] http://lists.denx.de/mailman/listinfo/eldk
