We are implementing IPv6 support in our product (which acts as a host). Our Product runs based on Monta Vista Linux 2.4 kernel (kernel configured with IPv6 support). We faced a problem that we could not ping our product from a Windows PC.

After some experiments, we could narrow down that the problem happens only when 3COM 4226T SuperStack ethernet switch is part of our LAN. If we use other switches, we do not face any problem.

We have PC connected to another ethernet switch (Foundry switch) and our product connected 3COM 4226T with both the switches cascaded. We were not able to ping the product from PC. The neighbor solicitation message is not reaching our product. We ran ethereal on another PC in Foundry switch. we could see the packet. But if we run ethereal on a PC connected to 3COM, we could not see the packet. Looks like 3COM 4226T is dropping neighbor solicitation multicast packet in some scenarios.

We suspected the IGMP snooping feature in 3COM 4226T. We disabled the feature. But after that, It did not work even when windows PC and our product are connected to same 3COM switch (this was working earlier when snooping was enabled)

Note: We tried connecting two windows PCs to 3COM 4226T directly. even that did not work irrespective of IGMP snooping disabled/enabled in 3COM.

Can anyone here please help me in understand the problem? Is there any known issues with 3COM 4226T ethernet switch and neighbor solicitation multicast.

Thanks in advance,
Sathish R