Command Line Interface Reference Guide > The Information Menu > /info/l3 Layer3 Information Menu > /info/l3/nbrcache IPv6 Neighbor Cache Information Menu
/info/l3/nbrcache
IPv6 Neighbor Cache Information Menu
This menu lets you dump IPv6 Neighbor Cache information.
 
[IP6 Neighbor Discovery Protocol Menu]
find - Show neighbor cache entry by IP address
port - Show neighbor cache entries on a single port
vlan - Show neighbor cache entries on a single VLAN
refpt - Show neighbor cache entries per SP
summary - Show IP6 neighbor cache summary
dump - Show all IP6 neighbor cache entries
 
IPv6 Neighbor Cache Information Menu (/info/l3/nbrcache) 
Command Syntax and Usage
find <IPv6 address>
 
Displays neighbor cache entry by IP address.
port <port number>
 
Displays neighbor cache entries on a single port.
vlan <vlan id>
 
Displays neighbor cache entries on a single VLAN.
refpt <sp id>
 
Displays neighbor cache entries per SP.
summary
 
Displays a summary of IPv6 neighbor cache entries.
dump
 
Displays all IPv6 neighbor cache entries.
IPv6 uses the Neighbor Discovery (ND) protocol to discover its neighbors’ link layer addresses and reachabilty. ND can also auto-configure addresses and detect duplicate addresses. ND enables routers to advertise their presence and address prefixes, and to inform hosts of a better next hop address to forward packets.
Note: Once the Neighbor Cache table reaches 2000 entries, table entries are replaced by adding the new entry and dropping the 2000th entry off the list. Table entries are kept until the entry is replaced by a new one. During this period, no new entries are used to sort for display.
The information collected from ND is stored in the Neighbor Cache. The Neighbor Cache maintains information about each neighbor such as:
*MAC Address
*Reachability state (see Neighbor Cache Reachability States)
*Neighbor type (see Neighbor Cache Neighbor Types)
*VLAN
*Ingress port
Neighbor Cache entries are added under the following situations:
*Entries are added when an IPv6 Interface or Virtual IP is operational.
*Reception of ND messages from neighbor.
*A device sends ND packets to resolve a link layer address to which it is attempting to send packets.
The following table describes the reachability states:
 
Neighbor Cache Reachability States 
State
Description
Incomplete
The link layer address of the neighbor has not yet been determined.
Reachable
The neighbor is known to have been reachable recently.
Stale
The neighbor is no longer known to be reachable, but until traffic is sent to the neighbor, no attempt should be made to verify its reachability.
Delay
The neighbor is no longer known to be reachable, and traffic has recently been sent to the neighbor.
Probe
The neighbor is no longer known to be reachable, and ND messages are sent to the neighbor to verify reachability.
The following table describes the neighbor types:
 
Neighbor Cache Neighbor Types 
Type
Description
Local
Pre-configured addresses on Alteon.
Dynamic
Neighbor addresses learned from ND.