# Neighbor Table Management

Each unit is equipped with a neighbor discovery module. The purpose of the neighbor discovery module is to detect all other units in the RF network and to add all necessary IP routes in order to be able to reach all neighboring units.
The neighbor discovery module only operates when the unit is configured in router mode.

## Neighbor Discovery

### Manual-Scan

Enabled (default): This is the default mode of operation. The Unit 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 on the web page, the Unit goes in the "Scanning For Neighbors" state. If a remote Unit initiates the "Scanning For Neighbors" state, the local Unit also goes in the "Scanning For Neighbors" state. In the "Scanning For Neighbors" state the Unit is learning about other remote Units and the remote Units are learning about the local Unit. The Unit goes from the "Scanning For Neighbors" state to the "Saving Neighbor Table" state when it stops learning anything new for a given amount of time (this value can be changed using the following parameter: neighborDiscovery.convergeTimeout (expressed in ms)). In the "Saving Neighbor Table" state, the content of the neighbor table is saved in nvram. Then, if the Unit reboots, the content of the neighbor table is restored from the nvram. Finally, the Unit goes from the "Saving Neighbor Table" state to the "Ready" state.

### Auto-Scan

The Unit starts in the "Scanning For Neighbors" state. In the "Scanning For Neighbors" state the Unit is learning about remote Units and the remote Units are learning about this Unit. The Unit goes from the "Scanning For Neighbors" state to the "Ready" state when it stops learning anything new for a given amount of time (this value can be changed using the following parameter neighborDiscovery.convergeTimeout). In the "Ready" state, the Unit is generating a Keep Alive packet. The rate at which the Keep Alive packet is generated can be changed by using the following parameter: neighborDiscovery.keepAliveTimeout. In the "Ready" state, the Unit performs broken link detection. The Unit is monitoring the Keep Alive packets of other Units (1 hop away). The Unit knows the interval at which the other Units are generating their Keep Alive packets. If Unit(A) fails to receive 4 Keep Alive packets in a row from Unit(B), Unit(A) removes Unit(B) from its neighbor table and goes in the "Scanning For Neighbors" state. If the user presses the <Force Scan> button in the web page, the Unit goes in the "Scanning For Neighbors" state. If any remote Units initiate the "Scanning For Neighbors" state, the local Unit also goes in the "Scanning For Neighbors" state.

### Disabled

The neighbor discovery module is disabled and the Viper will not learn about any new neighbors. It will not generate any Keep Alive packets.

## Local Status

Displays the status of the neighbor discovery module (Ready, Scanning, Saving, Disabled, and Testing Connectivity).

Ready: The neighbor discovery mode is in this state when it is not learning about other units. If the unit is operating in Manual-Scan mode, it does nothing. If the unit is operating in Auto-Scan mode, it monitors the keep alive messages of other units and sends its own Keep Alive message periodically.

Scanning for Neighbors: The unit is learning about other units. Other units are learning about this unit.

Disabled: The neighbor discovery module is disabled.

Saving Neighbor Table: In this state, the unit is saving all neighbor entries of type "Dynamic" into nvram. When the save is complete all these entries are now of type "Locked". This state only occurs when the neighbor discovery module operates in Manual-Scan of operation.

Displays the number of Vipers found in the network. Displays the amount of time it took for the discovery process.

## Discovered Viper Neighbors Information and Routing

### RF MAC Address

Displays the neighbor's unit RF MAC address and Netmask.

### RF IP Address

Displays the neighbor's unit RF IP address.

### Ethernet IP Address

Displays the neighbor's unit Ethernet IP address.

### RSSI

Displays the Received Signal Strength Indication (RSSI) in dBm from the neighbor unit to this local unit. The RSSI will only be displayed for remote units that are 1 hop away.

### Hop Count

Indicates the number of RF hops from the local unit to the neighbor unit.

### Next Hop

Indicates the RF MAC address of the local unit that's next on the path to the neighboring unit. (If the neighboring unit is only 1-hop away the field indicates the ID of the neighboring unit itself)

### Entry Type

Displays Entry Type of the neighbor's unit: Static, Dynamic, or Locked.

Static: This entry has been defined by the user. Can only be removed by the user. Cannot be replaced by a "Dynamic" or "Locked" entry. "Static" neighbor entries can be added in any neighbor discovery mode. If the user presses the "Save Config" button from the web page, all "Static" neighbor entries are saved in nvram. They are recovered after reboot.

Dynamic: A "Dynamic" neighbor entry is one that has been learned by the neighbor discovery algorithm. A "Dynamic" neighbor entry can be updated or deleted by the neighbor discovery algorithm when it detects changes in the topology.

Locked: A "Locked" neighbor entry is a "Dynamic" neighbor entry that has been saved into nvram. A "Locked" neighbor entry cannot be deleted by the neighbor discovery algorithm. If a unit is removed from the network, its neighbor entry must be removed manually from the Neighbor Tables of all the remaining units in the network. A "Locked" neighbor entry will be reset to "Dynamic" if the neighbor discovery mode is set to "Auto Scan".

### Control Operations

"Clear RSSIs" button deletes the RSSI units from the list.

"Clear List" button deletes the neighbor units from the table. Auto-Scan or Force Scan will populate the table with the neighbors that were discovered from the new discovery process. "Refresh" button must be clicked for the page to be updated with the new entries.

"Force Scan" button starts the discovery process and the tables are updated. "Refresh" button must be clicked for the page to be updated with the new entries.

"Test Connectivity" button starts a ping test to each neighbor in the table. "Reachable" will be displayed in the Connectivity Status if the ping succeeded.

"Add Static Entry" button will display a pop up window allowing the user to enter static entries. The RF MAC address, RF IP address, Ethernet IP address, RF netmask, Ethernet netmask, Hop count and the MAC address of the next Hop and a description must be entered. The attribute field indicates if the unit is an Access Point(AP) and/or a Relay Point(RP) and/or using NAT(NAT) and/or using the TCP proxy (PXY). Note that the netmask format is a.b.c.d. A neighboring unit can have virtual interfaces and PVID (port VLAN ID) defined. Valid PVID are from 0 to 4094 (0 means "no PVID").

"Delete Entry" button will display a pop up windows allowing the user to enter the MAC address of the unit they want deleted.

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