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DES-3326S Layer 3 Fast Ethernet Switch User’s Guide
Switch Management and Operating Concepts 139
• Down − No information has been received from
any router on the segment.
• Attempt − On non-broadcast multi-access
networks (such as Frame Relay or X.25), this
state indicates that no recent information has
been received from the neighbor. An effort
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. The
sequence number insures that routers always
get the most recent information. One router will
become the primary and the other will become
secondary. The primary router will poll the
secondary for information.
• Exchange − Routers will describe their entire
link-state database by sending database
description packets.