I have recently installed Ubuntu Ltsp server for a college and The college Lab has a Cisco switch. My server on the same vlan. So, in switch I configured the helper address of the ltsp server so every client get the address. But the problem comes to client having a Realtek card. they do not get the IP and gives the PXE-E51 error no dhcp found. But when I put the client Having a Broadcom LAN card it boots from the lan. So, this scenario works when I put normal switch and it boots both realtek and broadcom lan card.
I just need to know about that why the realtek nic does not get IP from cisco switch.
Your help will be highly appreciated.