ARP request

I am working on a router projects. My PC (two ethernet interface) run with RedHat linux. eth0 connect to a "managed switch. The switch three ports has been programmed (port 2 -- vlan 2, port 3 --vlan 3, port 7 -- vlan 2 & 3)
I also added vlan 2 & 3 to eth0. Therefore, I ran /sbin/ifconfig I can found etho, eth0.2 & eth0.3.

Connect two test PC to switch and enable DHCP. I can get IP address of two PCs. (192.168.1.200 which connect to port2 vlan2, 192.168.1.201 which connect to port 3 vlan3)

ping from 192.168.1.200 to 192.168.1.201. The Linux PC receive ARP request (I am 192.168.1.200 and who is 192.168.1.201). I ran /sbin/arp did not found arp entry

Question:

1. How can I enable ARP features on my Linux pc?
2. How I add MAC to ARP table?
3. Why DHCP request works fine without any arp request?

Thanks

The Linux PC ignores the request because the arp request is not for itself.

2. Use the arp command

3. The clients don't know the ip address of the dhcp server to begin with.

ping from 192.168.1.200 to 192.168.1.201. The Linux PC receive ARP request (I am 192.168.1.200 and who is 192.168.1.201). I ran /sbin/arp did not found arp entry

Maybe I'm misunderstanding your post or how your computers are actually connected to yuor switch, but I don't see a problem here. VLAN's separate broadcast domains. So why would you think an arp request would be sent from VLAN2->VLAN3???