DHCP offer issue

[user1201]

Hello, I have a problem on a switch c9407r in version 17.9.4a.

I have a device connected on a port (Gi1/0/11) on vlan 601 that sends a dhcp discovery request.
If I capture the uplink interfaces to the gateway (PO10) I can see the dhcp response with the dhcp offer frame.

However, on my equipment's interface, the dhcp offre frame doesn't go through.

Searching the logs I came across this:

113987: May 21 07:48:28.219: DHCP_SNOOPING: direct forward dhcp replyto output port: GigabitEthernet1/0/11.
113988: May 21 07:48:28.219: DHCP_SNOOPING: process new DHCP packet, message type: DHCPOFFER, input interface: Po10, MAC da: 408c.f451.12f4, MAC sa: 7854.bd5a.chfu, IP da: 192.185.1.5, IP sa: 192.185.1.1, DHCP ciaddr: 0.0.0.0, DHCP yiaddr: 192.185.1.5, DHCP siaddr: 192.232.43.12, DHCP giaddr: 192.185.1.1, DHCP chaddr: 408c.f451.12f4, efp_id: 21390295604, vlan_id: 601, bootpflag:0x0(Unicast)
113989: May 21 07:48:28.219: DHCP_SNOOPING: calling forward_dhcp_reply
113990: May 21 07:48:28.219: platform lookup dest vlan for input_if: Port-channel10, is NOT tunnel, if_output: NULL, if_output->vlan_id: 99999, pak->vlan_id: 601
113991: May 21 07:48:28.219: DHCP_SNOOPING: vlan 601 after pvlan check
113992: May 21 07:48:28.219: DHCP Memory dump is printed for direct forward reply

I can't find the problem. I tried to see if it could be dhcp snooping or device-tracking without success.

Do you have an idea of the problem?

[MHM Cisco World]

Can you draw simple topolgy and point where you enable dhcp snooping 

MHM

[user1201]

Hi MHM thank you for your reply

Here is a diagram of the topology as requested

Have a nice day !

[MHM Cisco World]

in L3SW you need

ip dhcp relay information trust-all 

or under interface 

ip dhcp relay information trust 

MHM

[David Ruess]

Hello,

Have you configured the interface that received the OFFER frame as a trusted port? When configuring DHCP Snooping allports are untrusted by default and wont process DHCP server type packets.

-David

[user1201]

Yesterday I tried to connect my PC to the Gi1/0/11 port in vlan 601 and I received an IP **bleep** directly.

So I think the problem is between my equipment and the switch sw02. Does the fact that the equipment sends ARP requests with an APIPA **bleep** cause the problem ?

[MHM Cisco World]

did you check my previous comment ?

also I see only device where is DHCP server connect or it local in L3SW?

MHM

[user1201]

Yes I will try your command on the swL3.

There are two dhcp servers on the network. The l3SW has two ip-helper to the dhcp servers

[MHM Cisco World]

this correct ?

[user1201]

Like that :

[MHM Cisco World]

[user1201]

Yes, during my test i connect PC on port Gi1/0/11 like the équipement. 

Port configuration are : 

switchport mode access 

switchport access vlan 601 

equipment on port gi1/0/11 is on vlan 601, dhcp discovery is on vlan 601

[user1201 · Accepted solution]

The problem has been found. Thank you for your help.
It was a fault on the link to the equipment.

However, I can't figure out why a link fault was preventing the dhcp offer from getting through.

There were a lot of input errors