Alcatel Carrier Internetworking Solutions 6648 - Manual (Page 72)

Troubleshooting a Source Learning Problem Troubleshooting Source Learning
page 3-4 OmniSwitch Troubleshooting Guide September 2005
In order to narrow down to a specific NI the following command can be used (any valid slot number can
be specified):
-> show mac-address-table slot 8
Legend: Mac Address: * = address not valid
Vlan Mac Address Type Protocol Operation Interface
------+-------------------+--------------+-----------+------------+-----------
114 00:c0:4f:12:f7:1b learned 10800 bridging 8/23
Total number of Valid MAC addresses above = 1
This does show that the MAC address 00:c0:4f:12:f7:1b is learned on port 8/23, see the figure on page 3-2 .
So, the source learning process for this workstation has been completed successfully.
Now, a single MAC address can be a member of multiple VLANs based on different protocols. To verify
that the MAC address has been learned in all of the VLANs, the above command can be used. The proto-
col field will be different based on different protocols being used and classified into different VLANs.
MAC addresses can also be viewed based on VLAN ID, using the following command:
->show mac-address-table 114
Legend: Mac Address: * = address not valid
Vlan Mac Address Type Protocol Operation Interface
------+-------------------+--------------+-----------+------------+-----------
114 00:c0:4f:12:f7:1b learned 10800 bridging 8/23
114 00:10:a4:b5:b5:38 learned 10806 bridging 16/16
Total number of Valid MAC addresses above = 2
The above command shows the two workstations learned in VLAN 114 on NI 8 and 16.
Whether it be a Layer 3 packet or layer 2, the first step is to have the source MAC address learned in the
MAC address table. Layer 3 involves resolution of ARP, for more details on ARP see troubleshooting
section of ARP, and then the available routes to the destination which involves routing, for more details on
Routing see troubleshooting section of Routing.
By default the MAC address aging time is set to 300 seconds. This can be viewed:
->show mac-address-table aging-time
Mac Address Aging Time (seconds) for Vlan 1 = 300
Mac Address Aging Time (seconds) for Vlan 114 = 300
This can be changed using the command:
->mac-address-table aging-time 500
Mac Address Aging Time (seconds) for Vlan 1 = 500
Mac Address Aging Time (seconds) for Vlan 114 = 500
This can also be changed on a particular VLAN:
->mac-address-table aging-time 600 vlan 114
It may be required to change the aging timer to a higher value to prevent the aging time of silent devices.
Another method by which silent devices can be accommodated is to use the permanent/static MAC
address assigned to a port using the command:
->mac-address-table permanent 00:10:a4:b5:b5:38 16/16 114