Discovery in the Cisco
environment
MPLS VPN-Tagging Server discovery in the Cisco environment
shows the design architecture of MPLS VPN overlapping IP discovery in the Cisco
environment.
MPLS VPN-Tagging Server
discovery in the Cisco environment
The
MPLS VPN-Tagging Server
performs SNMP discovery on Cisco routers or switches to discover VRF-based
network connections for the devices. When the
MPLS VPN-Tagging Server
discovers these connections, it sends the connection information to
IP Availability Manager
so
that
IP Availability Manager
is
able to distinguish overlapping IPs on the same device.
The flowchart in
MPLS VPN overlapping IP discovery flow in the Cisco
environment shows how MPLS VPN overlapping IP discovery works in the
Cisco environment.
MPLS VPN
overlapping IP discovery flow in the Cisco environment

Overlapping IP discovery of a Cisco device is triggered by
IP Availability Manager
when it sets a device’s IsDiscoveryInProgress attribute to True during the
course of discovering the device. The
MPLS VPN-Tagging Server
subscribes to IsDiscoveryInProgress attributes.
When the
MPLS VPN-Tagging Server
receives an IsDiscoveryInProgress attribute = True for either a Cisco router or
switch, it retrieves the address of the device’s SNMP agent from
IP Availability Manager
and
places the address in its discovery queue. It then initiates SNMP discovery on
the SNMP agent, obtains the IP route-distinguisher tag and other related
network connection information by querying the agent’s VRF-related MIB, and
writes that information to
IP Availability Manager
’s
Network Connection table.