IPv6 Neighbor Discovery
Fixed Switch Configuration Guide 25-11
Testing Network Connectivity
Use the ping ipv6 command to determine whether another device is on the network. Use the ping
ipv6 interface command to ping a link-local or global IPv6 address of an interface, specifying a
loopback, tunnel, or logical interface as the source.
To use the ping commands, configure the switch for network (in-band) connection. Both source
and target devices need to support ICMPv6 echo requests and echo responses. Fixed switch
devices have ICMPv6 echo requests and echo responses enabled by default. (Note that most IP-
capable devices support this feature for basic debugging.)
The switch can be pinged from any IP workstation with which the switch is connected through the
default VLAN (VLAN 1), as long as there is a physical path between the switch and the
workstation. The terminal interface sends three pings to the target station.
Use the traceroute ipv6 command to trace the hop-by-hop route from the switch to the destination
specified.
Refer to the CLI Reference for your platform for more information about the commands listed
below.
IPv6 Neighbor Discovery
The Neighbor Discovery (ND) protocol for IPv6 is defined in RFC4861. The neighbor discovery
protocol uses ICMPv6 messages to determine the link-layer addresses of nodes residing on the
same local link, to locate neighboring routers, to learn certain link and address configuration
information, and to track the reachability of neighbors.
Duplicate Address Detection
IPv6 Duplicate Address Detection (DAD) is described in RFC 4862. DAD uses Neighbor
Solicitation and Neighbor Advertisement messages to verify the uniqueness of an address. DAD
must be performed on unicast addresses prior to assigning them to an interface. An address
remains in a tentative state while DAD is being performed. If a tentative address is found to be a
duplicate, an error message is returned and the address is not assigned to the interface.
Use the ipv6 nd dad attempts command to change the number of Neighbor Solicitation messages
that can be sent for Duplicate Address Detection from the default value of 1. The no form of the
command returns the value to the default of 1. A value of 0 disables Duplicate Address Detection
on the interface.
The show ipv6 interface command displays the current DAD attempt setting.
Table 25-5 Testing Network Connectivity
Task Command
Test routing network connectivity by
sending IP ping requests to an IPv6
address.
ping ipv6 ipv6-addr [size num]
Test routing network connectivity,
specifying the interface to be used as
the source of the ping.
ping ipv6 interface {vlan vlan-id | tunnel tunnel-
id | loopback loop-id} {link-local-address ipv6-
lladdr | ipv6-addr} [size num]
Discover the routes that packets
actually take when traveling to their
destination through the network on a
hop-by-hop basis.
traceroute ipv6 ipv6-addr
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