Hello PL2,
first, we are all learning here, newbies in a way. second you can use different ways to check if your IXIA is properly connected to you Junos device.
Checking L1 first is a must, ensure that bringing down or removing links from one end (e.g. Junos Device) should bring the other device's interface down (e.g. IXIA) and viceversa.
In the IXIA IxNetwork application you will need to add the port, linecard and all that and you will be able to manage the link and see if it shows up. or green/yellow for me, most of the times.
Click on 'Add Ports' + 'Add Chassis' + select the card and port number and choose to 'add port'.
LLDP will work with Junos default configuration, you'll see under 'protocols lldp' hierarchy the 'interfaces all' statement and that should do it here, for the IXIA I foung this video for you:
IxNetwork LLDP - Classic
https://www.youtube.com/watch?v=NS1p0uhKAaE
That should help you ensure the LLDP is properly working.
Then just look how to add a flow and have lots of fun flooding traffic to your network. 🙂
Cheers!
Benjamin