background image
Chapter 4
OSPF Areas
Neighbor States
There are a total of eight states for OSPF neighbors:
Down No Hello packets have been received on the interface.
Attempt Neighbors must be configured manually for this state. It
applies only to NBMA network connections. (Note: This state is not rep-
resented in Figure 4.1)
Init Hello packets have been received from other routers.
2Way Hello packets have been received that include their own Router
ID in the Neighbor field.
ExStart Master/Slave relationship is established in order to form an
adjacency by exchanging Database Description (DD) packets. (The router
with the highest Router ID becomes the Master.)
Hello interval
The period between Hello packets.
OSPF options for neighbor formation.
Router priority
An 8-bit value used to aid in the election of the
DR and BDR. (Not set on point-to-point links.)
Router dead interval
The length of time allotted for which a Hello
packet must be received before considering the
neighbor down--four times the Hello interval,
unless otherwise configured.
The Router ID of the current DR.
The Router ID of the current BDR.
Neighbor router IDs
A list of the Router IDs for all the originating
router's neighbors.
T A B L E 4 . 1
OSPF Hello Packet Information (continued)
Originating Router
Copyright ©2001 SYBEX , Inc., Alameda, CA