Owner's Manual

Links 645
Link Discovery Status
If you click Next , a progress screen opens.
Figure 17-4. Link Discovery—Status
This displays the status as discovery progresses. Click the Link Topology button at the bottom of
the screen to see a logical topology view of what has been discovered (see
Chapter 21, Topology
Views
for specifics).
SNMP-Based Discovery
For many of the two link endpoints, the application interrogates the Bridge-MIB for values in
following tables.
.iso.org.dod.internet.mgmt.mib-2.dot1dBridge.dot1dBase.dot1dBasePortTable
.iso.org.dod.internet.mgmt.mib-2.dot1dBridge.dot1dTp.dot1dTpFdbTable
Learned ports in Dot1dTpFdbTable are the basis for all links created.
Once L2 links are known, link discovery tries to resolve the L2 learned links to L3 links using
.iso.org.dod.internet.mgmt.mib-2.ip.ipNetToMediaTable . This table shows the
L2 MAC address mapping to L3 IP addresses. At this point all link parameters have been
discovered from the device. The application must then associate the L3 address to known devices
to represent the links.
If the application cannot resolve an L3 IP address from the above process to the the port level of a
device, then it uses the top level managed object (MO) to represent the link endpoint.