[c-nsp] Cisco 2960G not passing DHCP

Curtis Piehler cpiehler2 at gmail.com
Sun Oct 22 18:24:20 EDT 2017

I'm racking my brains out on this yet it seems so simple unless I am
encountering a bug.

I have several host devices connected to the following switch,
Firewalls/PDUs, etc...:
Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 48    WS-C2960G-48TC-L   12.2(55)SE10          C2960-LANBASEK9-M

This switch sits down stream from a 3560G which uplinks to a firewall
(Router on a stick).  The problem I am encountering is that the devices
connected downstream of the 2960G are not receiving DHCP from the 3560G
switch or firewall.  Of course I have one DHCP at a time but to test
different devices that can serve out DHCP.  What's odd is that I have the
same exact model PDU connected to the 3560G and it obtains DHCP without

The devices downstream of the 2960G do not yield any MAC address.  I have
done all sorts of DHCP debugging and nothing comes up from the devices.  I
even tried moving the DHCP server down to the 2960G and I see no activity.
Statically assigning IPs to devices work no problem.

The PDUs are Raritan factory defaulted so when the port is shut/no shut
they are designed to get DHCP.  The firewall is a Fortinet with the
interface set to obtain DHCP.

Unfortunately I can not get a traffic sniffer on this switch but I'm
wondering if anyone has had this issue before or heard of this.


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