How to use Path Look-Up

How to use Path Look-Up

Unicast Path-Lookup

Enter the details:

  • Source IP / CIDR (it can be a network, but the total number of IPs has to be less than 255 including source and destination IPs)

  • Port (Source Port)

  • VRF (Virtual Routing and Forwarding Instance)

  • Destination IP / CIDR

  • Port (Destination Port)

  • Protocol: TCP/UDP/ICMP


If you’ve used a network instead of a single IP, you will have the option between:

Network Mode: simulation stats and ends with whole networks, individual hosts are not considered

Host Mode: simulation starts and ends with each host. It is limited to 255 hosts, source and destination combined.


Then click on submit:

Path Controls

With the mouse right-click, more options are enabled.
After opening the details, we can select the destination link to proceed with packet analysis.


Understand the path selection

To understand the decision taken by a device, right-click on the device and “show detail”. You will then be presented with the details. If you have more than one interface where the flow can come from, you will need to select the interface you want to look at. Similarly, if you have several interfaces that can be used to forward the traffic, you will have to choose one. Then in the middle of the table, you will see the forwarding decision:

In this example, we are looking at the device L33R4, which has 2 incoming interfaces and one forwarding for this flow:

Multicast Tree Look-Up

You want to understand how a certain multicast flow is used, you can use the Multicast Tree Look-Up. For that, just select the correct option and enter the relevant details

You will then see the Multicast Tree:

And you will have access to a lot of information regarding the Multicast forwarding decision:

Host To Gateway

To find out more details between a host and its network gateway, you can use this menu: Host To Gateway. You only need to provide the host, and you will the details: