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Introduction Troubleshooting Source Learning
page 3-2 OmniSwitch Troubleshooting Guide September 2005
Introduction
Source Learning Example
When a packet first arrives on NI source learning examines the packet and tries to classify the packet to
join its correct VLAN. If a port is statically defined in a VLAN, the MAC address is classified in the
default VLAN. Otherwise, if Group Mobility is being used the MAC address is classified into the correct
VLAN based on the rules defined.
As soon as the MAC address is classified in a VLAN, an entry is made in Source Address Pseudo-CAM
associating the MAC address with the VLAN ID and the Source Port. This Source Address is then relayed
to the CMM for management purposes.
If an entry already exists in MAC address database with the same VLAN ID and the same source port
number then no new entry is made. If VLAN ID or the source port is different from the existing entry in
MAC address database then the previous entry is aged out and a new entry is made in the MAC address
database. This process of adding a MAC address in the MAC address database is known as Source Learn-
ing.
A MAC address can be denied to learn on a port based on different policies configured through QOS or
Learned Port Security. A MAC address may be learned in a wrong VLAN based on the policies defined
for the port.
Note: This document does not discuss the basic operation of Source Learning. To learn about how Source
Learning works, refer to the “Managing Source Learning” in the appropriate OmniSwitch Network Config-
uration Guide.
OmniSwitch 7800
VLAN 114
Port: 8/23
IP: 10.40.114.50
MAC:00-C0-4f-12-F7-1B
VLAN 114
Port: 16/16
IP: 10.40.114.100
MAC: 00-10-A4-B5-B5-38