dhcp problem on 2960 switches

Hi All

I need your help

We have a dhcp server that was connected to Cisco 2960 which in turn was connected to alcatel switches, all worked fine. we changed the alcatel switches to cisco 2960's. We now have a problem that only devices directly connected to the original 2960(where the dhcp server is connected to) is receiving IP addresses we have now 4 other 2960's onthe network but we cannot get a IP address when we connect to any of the ports. doing a sniffer trace on the working switch the DHCP four way handshake is performed, discovery>>offer>>request>>>ack

On one of the other switches only the discovery is seen but no offer response from the dhcp server is seen therefore no ip address is received. the new switches only have portfast set and an ip address for vlan1 so I cannot understand what is stopping the dhcp traffic

Any Ideas



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You are trunking the vlan where the boxes are (logically) right? Can you manually set an IP on one node in the dhcp range and ping/ traceroute to the rest of the network?

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on the new switches, do you see the MAC address of the DHCP server in the mac table ?

Post the configs of the old switch and one of the new switches along with show version from both and show mac-address-table from both. also show ip int br

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Check to see if dhcp snooping is enabled. Don't know if the 2960's this feature, but when configured improperly, DHCP won't work.

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