How Does Spectrum Discover Connections using LLDP (Layer Link Discovery Protocol)

Products

• CA Spectrum
• DX NetOps

Issue/Introduction

How Does Spectrum Discover Connections using LLDP (Layer Link Discovery Protocol)

Environment

Release: All Supported Releases

Component: SPCDIS - Discovery and Modeling

Resolution

Spectrum is able to discover layer 2 connections by using the following LLDP information:

lldpMIB (1.0.8802.1.1.2)
- lldpLocChassisIdSubtype
- lldpLocChassisId
- lldpLocChassisDesc

lldpLocPortTable
- lldpLocPortIdSubtype 
- lldpLocPortId          
- lldpLocPortDesc  

lldpRemTable
- lldpRemChassisIdSubtype
- lldpRemChassisId 
- lldpRemChassisDesc     
- lldpRemPortIdSubtype   
- lldpRemPortId          
- lldpRemPortDesc

The below section outlines a few examples as to how this is achieved:

This example shows the lldpLocChassisId and lldpRemChassisId value of the MAC Address type. This value can be either Network address or chassisComponent etc., which is decided by the lldpLocChassisIdSubtype. Let's consider device A and device B:






The connection is made as Device A lldpRemTable contains Device B MAC Address and Device B lldpRemTable contains Device A MAC Address. 

This next example shows lldpLocPortId and lldpRemPortId Value of type port name. For reference, local ports are identified by lldpLocPortId or lldpLocPortDesc and neighbor ports are identified by lldpRemPortId or lldpRemPortDesc. 



Spectrum checks if Device B lldpLocPortId table contains the port value Eth1/12 and establishes the connection.



Spectrum checks if Device A lldpLocPortId table contains the port value Eth2/9 and establishes the connection.

Additional Information

- The connection will be formed only if both the devices are enabled with LLDP info.

- The port level connections will be resolved only if a proper and unique mapping is found. Connections will not be resolved in case of duplicate mapping.

- The connection would be resolved first based on portId comparison, if that is not resolving connections then portDesc information is used.

- lldpLocPortId/lldpRemPortId attribute value can be of type macAddress/ipAddress/portName/ifIndex. This type is decided based on lldpLocPortIdSubtype/lldpRemPortIdSubtype.