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6.2 | ![]() |
OSPF Operation | |
6.2.4 | ![]() |
Step 3: Discover routes |
On a multiaccess network, the exchange of
routing information occurs between the DR or BDR and every other
router on the network. As the DR and BDR on the 10.5.0.0 /16 network,
RTA and RTB will exchange link-state information.
Link partners on a point-to-point or
point-to-multipoint network also engage in the exchange process. That
means that RTB and RTC will share link-state data.
However, who goes first? This question
is answered in the first stage of the Exchange process, the ExStart
state. After the routers define their roles as
master and slave, they enter the Exchange state.
The routers acknowledge the receipt of
a DBD by sending an LSAck (Type 5) packet, which echoes back the sequence number
of the DBD. Each router compares the information that it receives
in the DBD with the information that it already has. If the DBD
advertises a new or more up-to-date link state, the router will enter
the Loading state by sending an LSR (Type 3) packet about that entry.
With the Loading state complete, the
routers have achieved full adjacency and entered into the Full state.
Figure
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