Прошивка свичей примерно такая.
enable dhcp_relay
config dhcp_relay hops 16 time 0
config dhcp_relay option_82 state enable
config dhcp_relay option_82 check disable
config dhcp_relay option_82 policy replace
config dhcp_relay option_82 remote_id default
config dhcp_relay add ipif System <IP DHCP сервера>
create iproute default <Шлюз по умолчанию>
config ipif System vlan default ipaddress <ip свича>/<маска> state enable
enable loopdetect
config loopdetect recover_timer 60
config loopdetect interval 10
config loopdetect mode port-based
config loopdetect ports 1-24 state enabled
config loopdetect ports 25-26 state disabled
config traffic control 1-24 broadcast enable multicast enable unicast enable action drop threshold 128 countdown 0 time_interval 5
config traffic control 25-26 broadcast disable multicast disable unicast disable action drop threshold 64 countdown 0 time_interval 5
config filter dhcp_server ports 1-24 state disable
config address_binding ip_mac ports 1-24 allow_zeroip disable
config address_binding ip_mac ports 1-24 forward_dhcppkt disable
disable address_binding trap_log
config address_binding dhcp_snoop max_entry ports 1-24 limit 10
enable address_binding dhcp_snoop
enable dhcp_local_relay
delete snmp community private
delete snmp community public
delete snmp user initial
create snmp community <my com> view CommunityView read_only
Дальше банальная настройка DHCP для работы с опцией 82, тут на форуме проскакивали готовые модули интеграции с nodeny, я думаю если поощрить авторов денюжкой они помогут.