User's Manual

001-5008-000 rev5_2.doc Page 91
11.2.1 Manual-SCAN
Manual-Scan is the default mode of operation. The ViPR starts in the “Ready” state. In the
“Ready” state, the unit is quiet (no neighbor discovery control messages are sent). If the
user presses the “Force Scan” button, the unit goes into the “Scanning for Neighbors” state.
If other units are in the "Scanning for Neighbors" state, the unit will automatically be
triggered to go into the "Scanning for Neighbors" state.
In the "Scanning for Neighbors" state, the ViPR is learning about other units and the other
units are learning about this unit. The unit goes from the "Scanning for Neighbors" state to
the "Saving Neighbor Table" state when it doesn’t learn anything new for a given amount of
time.
In the "Saving Neighbor Table" state, the content of the neighbor table is saved in nvram
(nonvolatile ram). If the unit reboots, the content of the neighbor table is restored from the
nvram.
The unit goes from the "Saving Neighbor Table" state to the "Ready" state.
11.2.2 Auto-SCAN
In the Auto-Scan mode, ViPR begins "Scanning for Neighbors". In the "Scanning for
Neighbors" state, ViPR discovers other ViPR units in the network and other ViPR units learn
about the ViPR initiating the scan.
ViPR goes from "Scanning for Neighbors" state to "Ready" state when it doesn’t discover
another ViPR for a given amount of time.
In "Ready" state, ViPR will generate a “keep alive” packet periodically. In "Ready" state,
ViPR performs broken link detection. ViPR is monitoring the “keep alive” packets of other
ViPRs (1 hop away). ViPR knows the interval period for other ViPRs generating their “keep
alive” packets. If ViPR (A) fails to receive four “keep alive” packets in a row from ViPR (B),
ViPR (A) removes ViPR (B) from its neighbor table and goes into the "Scanning for
Neighbors" state.
If a user presses the “Force Scan” button, ViPR goes into the "Scanning for Neighbors"
state. If other ViPRs are in the "Scanning for Neighbors" state, ViPR will automatically go
into "Scanning for Neighbors" state.
Note: Care should be taken when selecting Auto-Scan mode for the permanent operating
mode of a ViPR network. Auto-Scan mode could generate a large number of neighbor
discovery control messages in a large ViPR network
11.2.3 Disabled
In the disabled state, ViPR does not send neighbor discovery packets, nor does it process
neighbor discovery packets generated by other ViPRs. The user can enter static entries in
the Neighbor Table.
11.3 LOCAL STATUS
Local Status displays operating state information about the local discovery module. The
device shown in Figure 11.2 is currently Scanning for Neighbors. See below for additional
Discovery States.