# Why am I seeing the message "Device mapping does not exist for this map"?

This error is encountered when configuring a seed file for Layer2 mapping.

To start with, OpManager checks whether the given seed device is a Router or L3 Switch based on the criteria mentioned below:

## Criteria for Router

- .1.3.6.1.2.1.4.1 - IpForwarding should be 1
- .1.3.6.1.2.1.4.20.1.1 - Should return more than two interfaces.

## Criteria for Switch

- .1.3.6.1.2.1.17.1.4.1.1 - Bridge MIB should be implemented.

OpManager queries the OIDs in the following order: First CDP/LLDP OIDs, next IP routing table, then, if there is a switch connection, it queries the Bridge MIB and then ARP cache table. If OpManager is not able to get any device connection to the seed router/L3 switch, the error message "Device mapping does not exist for this map" is displayed.

Both the seed device (router/L3 switch) and the devices in the given IP range should be SNMP enabled.

## List of OIDs used for Layer2 Discovery

### BRIDGE-MIB

- .1.3.6.1.2.1.17.4.3.1.1
- .1.3.6.1.2.1.17.4.3.1.2
- .1.3.6.1.2.1.17.4.3.1.3
- .1.3.6.1.2.1.17.1.4.1.1
- .1.3.6.1.2.1.17.1.4.1.2

### RFC1213.MIB (NetToMediaTable)

- .1.3.6.1.2.1.4.22.1.1
- .1.3.6.1.2.1.4.22.1.2
- .1.3.6.1.2.1.4.22.1.3
- .1.3.6.1.2.1.4.22.1.4

### RFC1213 (IPRouteTable)

- .1.3.6.1.2.1.4.21.1.1
- .1.3.6.1.2.1.4.21.1.2
- .1.3.6.1.2.1.4.21.1.7
- .1.3.6.1.2.1.4.21.1.8
- .1.3.6.1.2.1.4.21.1.11

### CISCO-CDP.MIB

- .1.3.6.1.4.1.9.9.23.1.2.1.1.4
- .1.3.6.1.4.1.9.9.23.1.2.1.1.7
- .1.3.6.1.4.1.9.9.23.1.2.1.1.9

### LLDP.MIB

- .1.0.8802.1.1.2.1.4.1.1.4
- .1.0.8802.1.1.2.1.4.1.1.5
- .1.0.8802.1.1.2.1.4.1.1.8
- .1.0.8802.1.1.2.1.4.1.1.9
- .1.0.8802.1.1.2.1.4.1.1.12

### IF-MIB

- ifIndex - .1.3.6.1.2.1.2.2.1.1
- ifName - .1.3.6.1.2.1.31.1.1.1.1