Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 222)

194 Multi-Service IronWare Routing Configuration Guide
53-1003033-02
Synchronization of critical OSPF elements
LSA syncing and packing
When the LSA processing is completed on the active management module and the decision is
made to install the LSA in its link state database (LSDB), OSPF synchronizes that LSA to the
standby module. OSPF checks the current state of the database entry whether or not it is marked
for deletion. After checking the database state, OSPF packs the LSA status and other necessary
information needed for direct installation in the standby OSPF LSDB along with the LSA portion.
When the LSA reaches the standby module, OSPF checks the database entry state in the buffer
and takes appropriate action, such as adding, overwriting, updating, or deleting the LSA from the
LSDB.
Neighbor router synchronization
When the neighbor router is added in the active management module, it is synchronized and
added to the standby module. When the neighbor is deleted in the active module, it is synchronized
to the standby and deleted in the standby. When the neighbor router state becomes 2WAY or FULL,
the neighbor router is synchronized to the standby module.The following attributes of the neighbor
router is synchronized to the standby module:
• Neighbor router id
• Neighbor router ip address
• Destination router or backup destination router information
• Neighbor state 2WAY or FULL
• MD5 information
• Neighbor priority
Limitations
• If a neighbor router is inactive for 30 seconds, and if the standby module takes over in another
10 seconds, the neighbor router cannot be dropped. The inactivity timer starts again and takes
another 40 seconds to drop the neighbor router.
• In standby module, the valid neighbor states are LOADING, DOWN, 2WAY, and FULL. If the
active management processor (MP) fails when the neighbor state is LOADING, the standby
module cannot continue from LOADING, but the standby can continue from 2WAY and tries to
establish adjacency between the neighboring routers.
• The minimum OSPF dead-interval timer value is 40 seconds (default dead-interval value).
When the dead-interval value is configured less than this minimum value, OSPF NSR cannot be
supported.
Interface synchronization
Interface information is synchronized for interfaces such as PTPT, broadcast, and non-broadcast.
Interface wait time is not synchronized to the standby module. If an interface waits for 30 seconds
to determine the identity of designated router (DR) or backup designated router (BDR), and if the
standby module takes over, the wait timer starts again and takes another 40 seconds for the
interface state to change from waiting to BDR, DR, or DROther.