Search for	Example	Results
A single word	`cat`	Topics that contain the word "cat". You will also find its grammatical variations, such as "cats".
A phrase. You can specify that the search results contain a specific phrase.	`"cat food"` (quotation marks)	Topics that contain the literal phrase "cat food" and all its grammatical variations. Without the quotation marks, the query is equivalent to specifying an OR operator, which finds topics with one of the individual words instead of the phrase.

Search for	Operator	Example
Two or more words in the same topic	`AND` `and` `+` (plus symbol) `&` (ampersand)	`cat AND dog` `"cat food"+milk` `"cat food"&"dog food"`
Either word in a topic	`OR` `or` `\|` (pipe)	`cat OR dog` `cat \| dog`
Topics that do not contain a specific word or phrase	`NOT` `not` `!` (exclamation point)	`NOT cat` `! dog`
Topics that contain one string and do not contain another	`^` (caret)	`cat ^ mouse`
A combination of search types	`( )` parentheses	`cat + (dog \| mouse)` `cat \| dog + (! mouse)`

Universal DiscoveryContent Pack 28.00 (CP28)

Use > Discovery Modules > Network Infrastructure > Layer2 Discovery > Overview

Overview

The Layer2 package discovers the Layer2 topology that includes the switches tree topology (the backbone links between the switches) and also the end user connections to the switch-ports (the Layer2 CIs between a switch and a host).

The package can discover information from the following resources:

Forwarding Database (FDB)
Depending on device type, the FDB is found in the BRIDGE-MIB, QBRIDGE MIB, or STATISTICS-MIB.
Cisco Discovery Protocol MIB (CDP-MIB)
This MIB contains information collected by CDP about directly connected Cisco network devices.
Link Layer Discovery Protocol MIB (LLDP-MIB)
This MIB contains information collected by LLDP about directly connected network devices.

The Layer2 Topology Bridge-based by SNMP and Layer2 Topology VLAN-based by SNMP jobs select Layer2 connections information from the forwarding database, create the Layer2 CIs between a switch and an endpoint host, and put information about switch to switch Layer2 connections into files on the probe's file system.

The Process Layer2 Saved Files job selects data from the probe's file system (created by the Layer2 Topology Bridge-based by SNMP and Layer2 Topology VLAN-based by SNMP jobs) and creates switch to switch Layer2 connections.

The Layer2 Topology CDP-LLDP based by SNMP job selects Layer2 connections information from CDP or LLDP MIBs, and reports Layer2 connections from the discovered device to directly connected network devices.

The Layer2 package is based on the SNMP protocol.

The following image illustrates a router connecting overlapping VLANs/ELANs:

Send Help Center feedback