Cisco Catalyst 6500 User Manual page 3

OSPF
Switch(config)# router ospf 100
Switch(config−router)# nsf
Switch# show ip ospf
Routing Process "ospf 100" with ID 10.120.250.4
Start time: 00:01:37:484, Time elapsed: 3w2d
!−−− part of the output truncated
Supports Link−local Signalling (LLS)
!−−− indicates that OSPF is configured to be NSF aware
!−−− part of the output truncated
Non−Stop Forwarding enabled, last NSF restart 3w2d ago (took 31 secs)
!−−− indicates that OSPF is configured to be NSF capable
!−−− rest of the output truncated
Refer to Configuring NSF with SSO Supervisor Engine Redundancy for more information on NSF.
OOB MAC Synchronization
In distributed switching, each Distributed Feature Card (DFC) maintains its own CAM table. This means that
each DFC learns the MAC address and ages them, which depends on the CAM aging and traffic matching of
that particular entry. With distributed switching, it is normal that the supervisor engine does not see any traffic
for a particular MAC address for a while, so the entry can expire. There are currently two mechanisms
available to keep the CAM tables consistent between the different engines, such as DFC, which is present in
line modules, and Policy Feature Card (PFC), which is present in supervisor modules:
•
Flood to Fabric (FF)
•
MAC Notification (MN)
When a MAC address entry is aged out on the PFC, the show mac−address address <MAC_Address> all
command displays the DFC or PFC that holds this MAC address. In order to prevent the age out of an entry
on a DFC or PFC, even if there is not traffic for that MAC address, enable the MAC address synchronization.
Issue the mac−address−table synchronize global configuration command and clear mac−address−table
dynamic privileged EXEC command in order to enable the synchronization. This mac−address−table
synchronize command is available from Cisco IOS Software Releases 12.2(18)SXE4 and later. After you
enable it, it is possible to still see entries that are not present in PFC or DFC. However, the module has a way
to learn it from others that use Ethernet Out of Band Channel (EOBC).
Recommendations
Enable Out−of−Band MAC synchronization. It is used in order to synchronize mac−address tables across the
forwarding engines. If WS−6708−10G is present in the VSS system, MAC synchronization is automatically
enabled. If not, it must be enabled manually.
Dist−VSS(config)# mac−address−table synchronize
% Current activity time is [160] seconds