[c-nsp] mac-address-table synchronization

[Tassos Chatzithomaoglou]

I have a 7609/SUP720 (12.2(18)SXF10) chassis with the following results:

7609#sh platform hardware capacity forwarding
L2 Forwarding Resources
            MAC Table usage:   Module  Collisions  Total       Used       %Used
                               1                0  65536      18004         27%
                               2                0  65536      17001         26%
                               6                0  65536      14727         22%
                               7                0  65536        500          1%



7609#sh mac-address-table synchronize statistics

MAC Entry Out-of-band Synchronization Feature Statistics:
---------------------------------------------------------

     Module [1]
     -----------

     Module Status:
Statistics collected from module                    :  1
Number of L2 asics in this module                   :  0

     Global Status:
Status of feature enabled on the switch             :  off
Default activity time                               :  160
Configured current activity time                    :  160
...

     Module [2]
     -----------

     Module Status:
Statistics collected from module                    :  2
Number of L2 asics in this module                   :  0

     Global Status:
Status of feature enabled on the switch             :  off
Default activity time                               :  160
Configured current activity time                    :  160
...

All modules are WS-X6724-SFP with DFC3BXL.

According to this (http://www.cisco.com/en/US/docs/ios/lanswitch/command/reference/lsw_m1.html#wp1013301), synchronization is 
disabled by default (i guess that's what "off" means in the above output too).

What are the benefits/drawbacks of enabling it in the above case?

How does each frame get forwarded when its source port is in mod 1 and its destination port is in mod 2, while having 
synchronization disabled?

-- 
Tassos