uCMDB Tip: How does Layer 2 suite of jobs work?

UCMDB 9.x Content Pack (CP) 8:
* Whenever the successful connection was
established by SNMP protocol with a network device, discovery can start "VLANs
by SNMP" job.
* VLANs by SNMP job interrogates the switch to get the list of
VLANs configured on the device
* Then this job tries to re-connect to the
same device using the same community string and SNMP community postfix
"@<VLAN_ID>" (e.g. public@1002).
* In case of successful connection,
it interrogates the switch to get the list of physical ports configured for this
* If connection was unsuccessful or there are no physical ports
discovered for this VLAN, VLAN will not be reported, otherwise it gets reported
* Then VLAN Ports by SNMP starts to run and uses similar approach
(connects to switches with community string enriched by @<VLAN_ID>) to
discover physical ports of the VLANs and the Bridges.
* Afterwards Layer2
Topology VLAN based by SNMP and Layer2 Topology Bridge based by SNMP can start
and discover the Layer2 connectivity between nodes by interrogating switches to
get the relationships between Switch's local interfaces and remote interfaces
visible through specific physical ports. Once this information is discovered, we
build topology Switch -> Local Interface <- Layer2 Connection Remote
Interaface - Node (where node can be either computer or network device)
There's a new job called "Merge VLANs by Ports" which is designed to merge the
VLANs that span across multiple switches - it is based on having Layer2
connectivity between physical ports that are members of VLANs with equal VLAN
IDs on different switches.
There are several assumptions that must be met in
order to have the topology succesfully discovered:
* DDM should be able to
login to the network device with all the VLAN's IDs as community postfixes
Remote interfaces discovered from the switch should have unique MAC addresses in
UCMDB, otherwise UCMDB won't be able to reconcile the remote part of Layer2
Connection with Nodes/Switches in UCMDB

The differences between CP8 and
prior versions are:
* In
prior versions VLANs were reported regardless of the physical ports
configuration, which could cause duplication of CIs in UCMDB, longer time of
discovery run for VLAN Ports by SNMP and Layer2 Topology VLANs based by SNMP
* In
prior versions VLANs by SNMP job used incorrect MIB to interrogate the switch to
get the physical ports information, so incorrect physical ports could've been
reported, causing duplicate CIs
* In
prior versions Layer2 Topology VLANs/Bridge based by SNMP had a bug in the code
that only created Layer2 connections in cases when there were more than one
remote MAC address for specific Physical Port on a switch. This caused
non-discovering the Switch-Node topology and some Switch-Switch



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