C
HAPTER
 45
  |  IP Interface Commands
IPv6 Interface
–  1429  –
show ipv6
neighbors
This command displays information in the IPv6 neighbor discovery cache.
SYNTAX 
show ipv6 neighbors [vlan vlan-id | ipv6-address]
vlan-id - VLAN ID (Range: 1-4094) 
ipv6-address - The IPv6 address of a neighbor device. You can 
specify either a link-local or global unicast address formatted 
according to RFC 2373 “IPv6 Addressing Architecture,” using 8 
colon-separated 16-bit hexadecimal values. One double colon may 
be used in the address to indicate the appropriate number of zeros 
required to fill the undefined fields.
DEFAULT SETTING 
All IPv6 neighbor discovery cache entries are displayed.
COMMAND MODE 
Privileged Exec
EXAMPLE 
The following shows all known IPv6 neighbors for this switch:
Console#show ipv6 neighbors
State: I1 - Incomplete, I2 - Invalid, R - Reachable, S - Stale, D - Delay,
       P1 - Probe, P2 - Permanent, U - Unknown
IPv6 Address                            Age       Link-layer Addr   State VLAN
FE80::2E0:CFF:FE9C:CA10           4         00-E0-0C-9C-CA-10     R    1
Console#
Table 201: show ipv6 neighbors - display description  
Field Description
IPv6 Address IPv6 address of neighbor
Age The time since the address was verified as reachable (in seconds).
Link-layer Addr Physical layer MAC address. 
State The following states are used for dynamic entries:
I1 (Incomplete) - Address resolution is being carried out on the entry. 
A neighbor solicitation message has been sent to the multicast address of 
the target, but it has not yet returned a neighbor advertisement message.
I2 (Invalid) - An invalidated mapping. Setting the state to invalid dis-
associates the interface identified with this entry from the indicated 
mapping (RFC 4293). 
R (Reachable) - Positive confirmation was received within the last 
ReachableTime interval that the forward path to the neighbor was 
functioning. While in REACH state, the device takes no special action when 
sending packets.
S (Stale) - More than the ReachableTime interval has elapsed since the last 
positive confirmation was received that the forward path was functioning. 
While in STALE state, the device takes no action until a packet is sent.
D (Delay) - More than the ReachableTime interval has elapsed since the last 
positive confirmation was received that the forward path was functioning. 
A packet was sent within the last DELAY_FIRST_PROBE_TIME interval. If no 
reachability confirmation is received within this interval after entering the 
DELAY state, the switch will send a neighbor solicitation message and 
change the state to PROBE.