L2 network created successfully, but interfaces are not getting IPs

[Rasman Mubtasim Swargo]

Hi all,

I’m having trouble with a FABRIC slice where I created two nodes at MASS and NEWY and connected them with an L2 network, but the interfaces are not getting IP addresses.

Slice ID: 0c80b4be-6b12-4d87-8e85-e76bc8c44ddb
Slice name: iPerf3-tuned-nic-x6-64gb-512GB

What happened

Initially, I had two nodes:

• Node-MASS
• Node-NEWY

I created an L2 network between them. The network showed up in the topology, but the interfaces did not seem to get usable IPs.

To reconfigure, I fetched the latest slice topology, deleted the old network, and ran the modification script again. The new network (net4) now appears as Active, and the interfaces are attached, but the IP addresses are still None.

Modification code used

## NOTE: Always get the latest slice topology before requesting any updates
slice = fablib.get_slice(slice_name)

# Removing NIC1 from Node1
node1 = slice.get_node(name="Node-MASS")
node2 = slice.get_node(name="Node-NEWY")
net1 = slice.get_network(name="net1")

net1.delete()

net2 = slice.add_l2network(name="net4", subnet=IPv4Network("192.168.2.0/24"))

iface1 = node1.get_interfaces()[0]
iface1.set_mode('auto')
net2.add_interface(iface1)

iface2 = node2.get_interfaces()[0]
iface2.set_mode('auto')
net2.add_interface(iface2)

slice.submit()

Current state

After running the script:

• net4 is created and shows as Active
• both nodes are still Active
• the interfaces are attached to net4
• but the IP address fields remain None

What I checked

When I try to retrieve the IP from the interface, I get None:

node2_addr = node2.get_interface(network_name="net4").get_ip_addr()
print(node2_addr)
stdout, stderr = node1.execute(f'ping -c 5 {node2_addr}')

This prints:

None

Question

What can I do to fix this? I want a network with great speed.

Any guidance would be appreciated.

[Tom Lehman]

Hello, The FABRIC MASS dataplane link was having some problems, however that should be working now. Please try your service again and let us know if all is working.  Thanks, Tom

[Rasman Mubtasim Swargo]

Tom Lehman wrote:

Hello, The FABRIC MASS dataplane link was having some problems, however that should be working now. Please try your service again and let us know if all is working.  Thanks, Tom

Hello,

Thanks for the update.

I removed the old slice and created a new one to retry from scratch, but I am still seeing the same issue. The new slice is:

• Slice ID: f00b699f-7332-4cd5-b4fd-f64b0da3afe3
• Slice name: iPerf3-tuned-nic-x6-64gb

In this new slice, the L2 network was created successfully and shows Active, and both nodes are also Active. The interfaces are attached to net1, but the IP Address field still remains None for both sides.

Current setup:

• Node-FIU at FIU
• Node-KANS at KANS
• Network: net1
• Subnet: 192.168.1.0/24

From the topology view:

• Node-FIU-nic1-p1 is attached to net1, mode auto, IP Address None
• Node-KANS-nic1-p1 is attached to net1, mode auto, IP Address None

So the issue still seems to be that the network is created, but IPs are not being assigned to the interfaces.

Please let me know whether there is an additional step needed for IP assignment on L2 networks, or if this indicates another dataplane/control-plane issue.

Thank you.

 

Code:

#Create Slice
slice = fablib.new_slice(name=slice_name)

net1 = slice.add_l2network(name=network_name, subnet=subnet)

for s in sites:
# Node1
node1 = slice.add_node(name=f”Node-{s}”, cores=cores, ram=ram, disk=disk, site=s, image=image)

iface1 = node1.add_component(model=model_name, name=nic_name).get_interfaces()[0]
node1.add_component(model=’NVME_P4510′, name=’nvme1′)
iface1.set_mode(‘auto’)
net1.add_interface(iface1)
net1.set_bandwidth(60)

node1.add_post_boot_upload_directory(‘node_tools’,’.’)
node1.add_post_boot_execute(‘sudo node_tools/host_tune.sh’)
# node1.add_post_boot_execute(‘node_tools/enable_docker.sh {{ _self_.image }} ‘)
# node1.add_post_boot_execute(‘docker pull fabrictestbed/slice-vm-ubuntu20-network-tools:0.0.1 ‘)

#Submit Slice Request
slice.submit();

[Komal Thareja]

Hi Rasman,

Which JH container are you using?

Best,

Komal

[Rasman Mubtasim Swargo]

Komal Thareja wrote:

Hi Rasman,

Which JH container are you using?

Best,

Komal

Hi Komal,

I am using the default FABRIC JupyterHub container (

(default) FABRIC Examples v1.9.0, FABlib v1.9.3: released: 07/28/2025, stable: Summer 2025

) from the FABRIC portal, not a custom local environment.

If you need additional details, I can also share those.

Best,
Rasman

[Komal Thareja]

Hi Rasman,

I tried both your shared NICs example and the iperf3 (CX5) notebook, and I do see IPs being configured on the VMs.

Could you please run the following notebook:
jupyter-examples-*/configure_and_validate/configure_and_validate.ipynb?

It’s possible that your bastion keys have expired, which may be preventing fablib from properly configuring the nodes.

I’ve attached a snapshot of the output from my runs below for reference.

Best,
Komal

[Rasman Mubtasim Swargo]

Yes. That was the case. My bad. Do I need to delete the slice and then reserve again, or there is any way to continue with the existing slice?

 

Thank you for your assistance.

[Komal Thareja]

You should be able to re-use the existing slice.

Just run the following in a cell.

slice=fablib.get_slice(slice_name)

slice.post_boot_config()

slice.list_nodes();

slice.list_interfaces();

Thanks,

Komal

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