Support CoS marking for FortiGate DHCP client requests

FortiOS now supports Class of Service (CoS) marking on locally generated DHCPv4 and DHCPv6 client packets. This enhancement enables FortiGate to obtain IP addresses from service providers that require CoS-marked DHCP requests.

New options are available:

config system interface
    edit <name>
        ...
        set mode dhcp
        set dhcp-egress-cos [cos0 | cos1 | cos2 | cos3 | cos4 | cos5 | cos6 | cos7]              
        set role lan
        config ipv6
            set ip6-mode dhcp
            set dhcp6-egress-cos [cos0 | cos1 | cos2 | cos3 | cos4 | cos5 | cos6 | cos7]         
        end
        set interface "port2"
        set vlanid 3825
        ...
    next
end

Option	Description
dhcp-egress-cos [cos0 | cos1 | cos2 | cos3 | cos4 | cos5 | cos6 | cos7]	CoS in VLAN tag for outgoing DHCP packets (default = cos0). Available only for VLAN interface in DHCP mode.
dhcp6-egress-cos [cos0 | cos1 | cos2 | cos3 | cos4 | cos5 | cos6 | cos7]	CoS in VLAN tag for outgoing DHCPv6 packets (default = cos0). Available only for VLAN interface in DHCPv6 mode.

Example

This example shows how to enable CoS marking in VLAN tags for outgoing DHCPv4 or DHCPv6 packets.

To enable CoS marking on a VLAN interface:

1. For a VLAN interface in DHCP mode, enable CoS markings for DHCPv4 and DHCPv6:

   This example enables cos6 markings.

   config system interface
       edit "p2v3825"
           set vdom "root"
           set mode dhcp
           set allowaccess ping
           set dhcp-egress-cos cos6              
           set device-identification enable
           set role lan
           set snmp-index 16
           config ipv6
               set ip6-mode dhcp
               set ip6-allowaccess ping
               set dhcp6-egress-cos cos6         
           end
           set interface "port2"
           set vlanid 3825
       next
   end

2. Run the sniffer to capture DHCPv4 and DHCPv6 frames and check the CoS field in 802.1Q header:

   • DHCPv4:

     Frame 12: 594 bytes on wire (4752 bits), 594 bytes captured (4752 bits)
     Ethernet II, Src: RealtekU_0f:81:e8 (52:54:00:0f:81:e8), Dst: Broadcast (ff:ff:ff:ff:ff:ff)
     802.1Q Virtual LAN, PRI: 6, DEI: 0, ID: 3825
         110. .... .... .... = Priority: Internetwork Control (6)   
         ...0 .... .... .... = DEI: Ineligible
         .... 1110 1111 0001 = ID: 3825
         Type: IPv4 (0x0800)
     Internet Protocol Version 4, Src: 0.0.0.0, Dst: 255.255.255.255
     User Datagram Protocol, Src Port: 68, Dst Port: 67
     Dynamic Host Configuration Protocol (Request)

   • DHCPv6:

     Frame 616: 160 bytes on wire (1280 bits), 160 bytes captured (1280 bits)
     Ethernet II, Src: Fortinet_25:23:ec (e0:23:ff:25:23:ec), Dst: IPv6mcast_01:00:02 (33:33:00:01:00:02)
     802.1Q Virtual LAN, PRI: 6, DEI: 0, ID: 3825
         110. .... .... .... = Priority: Internetwork Control (6)   
         ...0 .... .... .... = DEI: Ineligible
         .... 1110 1111 0001 = ID: 3825
         Type: IPv6 (0x86dd)
     Internet Protocol Version 6, Src: fe80::e223:ffff:fe25:23ec, Dst: ff02::1:2
     User Datagram Protocol, Src Port: 546, Dst Port: 547