Hp 25xx doesn't see devices

[Vladii01]

Hi

I faced with problem in switches 25xx series. In the net presents several PLC (programmable logic controller) which has standart IP addresses/mask like other devices. PLC works through the net properly, but  ping test to their addresses, issued from CLI string of that switches, return with message "Target did not respond" and I don't see them in the switches arp table and mac address table. At the same time, after ping command issued from any comp connected to that switch (ping return usual message with answers from PLC ), arp table of that computer show it address (IP and mac) to me. So I think PLC works properly and can give right answers to ping tests but only if it was issued from computer, not from switch. Question - how can it be? May be someone else faced with problem like these?      

[Matt Kunard]

There shouldn't be any difference between an ARP or ICMP request sent from the switch itself versus from a computer attached to the switch assuming everything is in the same VLAN/subnet.  Do these devices have regular L2 MAC addresses or do they possibly have multicast L2 addresses?

You could try and capture the traffic between the switch and the devices to see what the difference are in the traffic coming from the switch versus the attached computers or if the traffic is even reaching the device.

[Vladii01]

Hi

   Devices have L2 MAC adresses like these: 67.77.01.03.D0.26. As for me it doesn't looks like multicast MAC address.