DHCP server not working on trusted ports on dhcp-snooping enabled 3Com 4200G

[vasek125]

Hello. I have 3Com switches in a simple star topology. 3Com 5500 SS4 in the middle - makes inter vlan routing and dhcp relay on every configured vlan interface. Hosts are connected to 4200G and 4210 switches. All servers (including dhcp servers) are connected to one 4200G switch. Some hosts are also connected to this switch. When I enable dhcp-snooping on this switch, dhcp stops working for all LAN. I globally enabled dhcp-snooping and made dhcp-snooping trusted dhcp server ports and uplink port (to 5500 switch). Problem is probably with DHCP Option 82. Hosts sends broadcasts and 5500 makes dhcp relay to dhcp servers on 4200G switch. I tried to enable dhcp-snooping information enable and dhcp-snooping information strategy keep on 4200G but it does not work. When dhcp-snooping is enabled, hosts sends multiple DHCP Requests and dhcp server send multiple DHCP ACKs, but host will never get IP (so switch must drop or modify these packets). What is wrong? Where is the problem?

P.S. This thread has been moved from Switching > Legacy to Comware-Based. - Hp Forum Moderator