@ewolf You configured port 3 on the MX68 as trunk port with native vlan 100. Does the native vlan match on the HP switch? In HP terminology, vlan 100 should be untagged on the port where the MX68 is connected. Also, Are you running DHCP server on the MX68? If not, you might want to configure an IP-Helper for the DHCP server, Make sure you have that config in place.
Cheers!
Raj
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