D-Link DES-3326SR User Manual page 127

DES-3326SR Layer 3 Fast Ethernet Switch User's Guide
Building Adjacency
Two routers undergo a multi-step process in building the
adjacency relationship.
description of the steps required:
• Down − No information has been received from
any router on the segment.
•
Attempt
networks (such as Frame Relay or X.25), this
state indicates that no recent information has
been received from the neighbor.
should be made to contact the neighbor by
sending Hello packets at the reduced rate set by
the Poll Interval.
• Init − The interface has detected a Hello packet
coming from a neighbor but bi-directional
communication has not yet been established.
• Two-way − Bi-directional communication with a
neighbor has been established. The router has
seen its address in the Hello packets coming
from a neighbor. At the end of this stage the DR
and BDR election would have been done. At the
end of the Two-way stage, routers will decide
whether to proceed in building an adjacency or
not. The decision is based on whether one of the
routers is a DR or a BDR or the link is a point-
to-point or virtual link.
• Exstart − (Exchange Start) Routers establish the
initial sequence number that is going to be used
in the information exchange packets.
sequence number insures that routers always
get the most recent information. One router will
become the primary and the other will become
The following is
−
On non-broadcast
115
a simplified
multi-access
An effort
The