Using LLDP to Identify Ports

Introduction

There are times when it would be valuable to know what is at the other end of a CAT cable. Assuming this cable is connected to a Tellabs Optical LAN system, this document explains the necessary configuration and how Wireshark, traffic analysis software, can be used to identify what port of an ONT a cable connects to.

Document Number

ENG-010450

Applies To

FP27.1 and later releases that support LLDP. The screen shots used below are from an FP28.0 EMS. This method of identification requires a laptop with a Network Interface and the Wireshark software.

Creating & Assigning LLDP Profiles

First, LLDP must be enabled on all ports, which requires creating an LLDP profile and assigning it to all lines. To create an LLDP profile, click on the Profiles' menu item and select Ethernet Port. Click on the LLDP tab and then select the New or Edit icon. Figure 1: LLDP Profile Suitable for Asset Management shows the default configuration for an LLDP profile. The name "Asset_Management" has been given to this new profile. Be sure that the OLT User Label(TID)/Chassis(1) is selected for the Chassis Id Source field. This LLDP profile is not suitable for VoIP phones.

Figure 1: LLDP Profile Suitable for Asset Management

Once the profile has been created, the profile should be assigned to all lines. Note: this profile creation can also be done at initial commissioning time and assigned to all lines using auto-provisioning. However, if this is a previously commissioned system, the easiest way to assign the new LLDP profile to all lines is to select a QOIU7 at a time and bulk apply the profile. In Figure 2: Select All Lines, all the lines on PON 10-2 were selected (using Ctrl-A or highlighting with mouse). Then, right click on the selected lines and choose the menu option "Profile and Admin State."

Figure 2: Select All Lines

In Figure 3: Selecting the LLDP Profile, the new "Asset Management" profile is selected for the LLDP profile to apply to all selected lines. Next, click apply.

Figure 3: Selecting the LLDP Profile

After applying the profile to all lines on the PON, the LLDP messaging will flow to the ONT UNI  ports. Wireshark can be used to capture the LLDP packets that identify the port.

First, run Wireshark. Select the interface that will be used to capture packets. Be sure the correct interface is selected. One way to tell is to select the interface with the Ethernet cable inserted, and then remove the cable. Clicking on the "details" (see Figure 5: Wireshark LLDP Packet Capture) of an interface will indicate that the "Link status" of the connection is "Disconnected." Reconnect the cable, re-open the details, and verify that the "Link status" transitions to Connected. Exit the details and click the "start" button while the appropriate interface is selected to start the packet capture.

Figure 4: Select Interface for Packet Capture

Next, filter LLDP messages by typing "lldp" in the Filter field. The field should be green if you have typed the filter correctly. The Filter field will be red if you typed "LLDP" because the filter is case-sensitive.

Finally, watch for a captured packet with a Reliance MAC. Figure 5: Wireshark LLDP Packet Capture shows an example of the LLDP messaging as displayed by Wireshark. Note that the Port-Id indicates the AID of the port which you are attached to.  The System Name gives the name of the OLT which hosts this ONT.

Figure 5: Wireshark LLDP Packet Capture

Summary

Using Wireshark packet captures is a very effective method for determining ONT port information.

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