DHCP Issue

[dijeshkeloth]

We had our cisco ip phones working with dhcp running on cisco 3850 switch (16.3.6). The SVIs were running on this switch. Recently, we introduced a firewall and moved all the SVIs to the firewall, however the cisco switch continued to act as DHCP server. The firewall relays the dhcp request from cisco phones to the switch. We noticed that the cisco phones fail to get ip address via dhcp. There are other devices that continue to renew dhcp just fine. The cisco switch log shows the below:

Oct 2 08:00:21.101: DHCPD: DHCPREQUEST received from client 012c.0ee9.0402.cf.
Oct 2 08:00:21.101: DHCPD: DHCPREQUEST received on interface Vlan1121.
Oct 2 08:00:21.101: DHCPD: FSM state change INVALID
Oct 2 08:00:21.101: DHCPD: Workspace state changed from INIT to INVALID
Oct 2 08:00:21.101: DHCPD: Client either rebooted or rebinding we are seeing the client for first time
Oct 2 08:00:21.101: DHCPD: Finding a relay for client 012c.0ee9.0402.cf through relay 172.21.210.2.
Oct 2 08:00:21.101: DHCPD : Locating relay for Subnet 172.21.210.2
Oct 2 08:00:21.102: DHCPD: Sending notification of ASSIGNMENT FAILURE:
Oct 2 08:00:21.102: DHCPD: htype 1 chaddr 2c0b.e204.02cf
Oct 2 08:00:21.102: DHCPD: giaddr = 172.21.210.2
Oct 2 08:00:21.102: DHCPD: interface = Vlan1021
Oct 2 08:00:21.102: DHCPD: class id 436973636f2053797374656d732c20496e632e2049502050686f6e652043502d3838313100
Oct 2 08:00:21.102: DHCPD: Sending notification of ASSIGNMENT_FAILURE:
Oct 2 08:00:21.102: DHCPD: due to: CANT FORWARD
Oct 2 08:00:21.102: DHCPD: htype 1 chaddr 2c0b.e204.02cf
Oct 2 08:00:21.102: DHCPD: giaddr = 172.21.210.2
Oct 2 08:00:21.102: DHCPD: interface = Vlan1121
Oct 2 08:00:21.102: DHCPD: class id 436973636f2053797374656d732c20496e632e2049502050686f6e652043502d3838313100

[balaji.bandi]

Oct 2 08:00:21.101: DHCPD: DHCPREQUEST received from client 012c.0ee9.0402.cf.
Oct 2 08:00:21.101: DHCPD: DHCPREQUEST received on interface Vlan1121.
Oct 2 08:00:21.101: DHCPD: FSM state change INVALID
Oct 2 08:00:21.101: DHCPD: Workspace state changed from INIT to INVALID

as per above message DHCP relay not getting DHCP offer from DHCP Server. ? post relavant configuration ASA and Switch side to look.

example config :

https://www.cisco.com/c/en/us/support/docs/security/adaptive-security-appliance-asa-software/116265-configure-product-00.html

[dijeshkeloth]

Thanks Balaji for your reply.

The dhcp configuration on the switch is as follows:

ip dhcp pool DLP_Logistics_Voice
network 172.21.210.0 255.255.255.0
default-router 172.21.210.2
dns-server 192.168.20.39
option 150 ip 172.21.210.70
lease 7

We have cisco FTD rather than ASA

Actually, there are devices for which dhcp works fine. The cisco phone does a dhcp request rather than broadcast to retain its ip address. What I think is as the cisco switch receives this request via a dhcp relay, it does not accept it, however new phones seems to get ip address.

[Georg Pauwen]

Hello,

does the swithch have DHCP snooping enabled ?

[dijeshkeloth]

No

[balaji.bandi]

when  you say new phones working? can you explain, what model not working what is not working to get more clarity?

some legacy stuff may require some tweak