Dell Networking N4000 Series Configuration Manual page 1040

The administrator is using a Microsoft DHCP server. Microsoft DHCP servers
do not have native support for DHCP Option 82, but it can be added using
the DhcpServerCalloutEntry API to retrieve the information via the
DhcpHandleOptionsHook configured on the switches. Adding Option 82
support enables choosing whether or not a particular DHCP server should
respond to the DHCP request, and whether it should only respond to requests
from a particular switch (as identified by the remote-id) and port (as
identified by the circuit-id). For further information and an example, follow
this web link:
http://blogs.technet.com/b/teamdhcp/archive/2009/07/06/dhcp-server-callout-
api-usage.aspx
For Linux-based systems, which natively support option 82, a configuration to
serve two private pools (Pool1 and Pool2) and one public pool of DHCP
addresses based upon the remote-id and circuit-id might look like the
following:
dhcpd.conf file:
class "Pool1" {
match option agent.remote-id;
match option agent.circuit-id;
}
subclass "Pool1" "Switch A" "Gi1/0/1";
subclass "Pool1" "Switch A" "Gi1/0/2";
subclass "Pool1" "Switch A" "Gi1/0/3";
class "Pool2" {
match option agent.remote-id;
match option agent.circuit-id;
}
subclass "Pool2" "Switch B" "Gi1/0/1";
subclass "Pool2" "Switch B" "Gi1/0/2";
subclass "Pool2" "Switch B" "Gi1/0/3";
shared-network Public {
subnet 10.1.222.0 netmask 255.255.254.0 {
pool {
deny members of "Pool1";
deny members of "Pool2";
option routers 10.1.222.1;
1040
Configuring DHCP Server and Relay Settings