Introduction to IPv6

 

Configuration and Management

 

 

N o t e

In IPv6 for the switches covered in this guide, the default route cannot be

 

statically configured. Also, DHCPv6 does not include default route configura­

 

tion.)

 

Refer to “Default IPv6 Router” on page 4-28and “View IPv6 Gateway, Route,

 

 

and Router Neighbors ” on page 4-29.

 

Neighbor Discovery (ND) in IPv6

 

The IPv6 Neighbor Discovery protocol operates in a manner similar to the IPv4

 

ARP protocol to provide for discovery of IPv6 devices such as other switches,

 

routers, management stations, and servers on the same interface. Neighbor

 

Discovery runs automatically in the default configuration and provides

 

services in addition to those provided in IPv4 by ARP. For example:

 

■ Run Duplicate Address Detection (DAD) to detect duplicate unicast

 

address assignments on an interface. An address found to be a duplicate

 

is not used, and the show ipv6 command displays the address as a duplicate.

 

■ Quickly identify routers on an interface by sending router solicitations

 

requesting an immediate router advertisement (RA) from reachable

 

routers.

 

■ If a default router becomes unreachable, locate an alternate (if available

 

on the interface).

 

■ Learn from reachable routers on the interface whether to use DHCPv6 or

 

stateless address autoconfiguration. In the latter case, this also includes

 

the address prefixes to use with stateless address autoconfiguration for

 

routed destinations. (A DHCPv6 server can also be used for “stateless”

 

service; that is, for configuring the interface for access to other network

 

services, but not configuring a global IPv6 unicast address on the inter­

 

face. Refer to “Neighbor Discovery (ND)” on page 4-17.)

 

■ Use multicast neighbor solicitations to learn the link-layer addresses of

 

destinations on the same interface and to verify that neighbors to which

 

traffic is being sent are still reachable.

 

■ Send a multicast neighbor advertisement in response to a solicitation from

 

another device on the same interface or to notify neighbors of a change

 

in the link- layer address.

■

■

Advertise anycast addresses that may be configured on the device.

Determine the MTU (Maximum Transmission Unit) for the interface from router advertisements.

For more on IPv6 neighbor discovery applications, refer to “Neighbor Discovery (ND)” on page 4-17.

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