Option 1 technically isn’t everything as there’s no DNS server or domain name info (RFC 6106). Need both the router to support the sending of the info and the end system to know what to do w/ it.
For option 3, you still need to control the SLAAC process w/ the RA’s (e.g. how the prefix in the RA should be used) otherwise the end system will end up a DHCP and SLAAC address
The ipv6 nd prefix 2001:DB8:CAFE:120::/64 no-autoconfig command (set A flag off), coupled with the M flag set on, succeeds in getting Windows 7 to just populate one address, while still installing a default route on the client.
no-autoconfig
(Optional) Indicates to hosts on the local link that the specified prefix cannot be used for IPv6 autoconfiguration. The prefix will be advertised with the A-bit clear.
When autoconfiguration is “on” (by default), it indicates to hosts on the local link that the specified prefix can be used for IPv6 autoconfiguration.
The configuration options affect the L-bit and A-bit settings associated with the prefix in the IPv6 ND Router Advertisement, and presence of the prefix in the routing table, as follows:
Default L=1 A=1 In Routing Table
no-onlink L=0 A=1 In Routing Table
no-autoconfig L=1 A=0 In Routing Table
no-onlink no-autoconfig L=0 A=0 In Routing Table
off-link L=0 A=1 Not in Routing Table
off-link no-autoconfig L=0 A=0 Not in Routing Table
A-bit – Autonomous Address Autoconfiguration Flag tells the node it should perform stateless address assignment (SLAAC RFC 4862)
L-bit – On-Link Flag tells the node that the prefix listed in the RA is the local IPv6 address
M-bit – Managed Address Config Flag tells the host if it should use stateful DHCPv6 (RFC 3315) to acquire its address and other DHCPv6 options
O-bit – Other Config Flag tells the host that there is other information the router can provide, such as DNS information defined in Stateless DHCPv6 (RFC 3736)
RFC 4862 = "autonomous address-configuration flag", indicates whether or not the
option even applies to stateless autoconfiguration. If it does,
additional option fields contain a subnet prefix, together with
lifetime values, indicating how long addresses created from the
prefix remain preferred and valid.
ipv6 nd ra dns-suffix ipv6.vmwcs.com
To configure the IPv6 router advertisement of DNS server addresses on an interface, use the ipv6 nd ra dns server command in interface configuration mode. To remove the IPv6 router advertisement of DNS server addresses, use the no form of this command.
ipv6 nd ra dns server ipv6-address seconds
no ipv6 nd ra dns server ipv6-address
Syntax Description
seconds
The amount of time (in seconds) that the Domain Naming System (DNS) server is advertised in an IPv6 router advertisement (RA). The range is from 200 to 4294967295.
Command Default
The DNS server is not advertised in an IPv6 RA.
Command Modes
Interface configuration (config-if)
Command History
Release Modification
Cisco IOS XE Release 3.9S
This command was introduced.
Usage Guidelines
You can use the ipv6 nd ra dns server command to configure up to eight DNS server addresses in an RA.
If you configure a seconds value of zero, the DNS server will no longer be used.
Examples
The following example configures a DNS server with an IPv6 address of 2001:DB8:1::1 to be advertised in an RA with a lifetime of 600 seconds:
Router(config)# interface ethernet 0/0
Router(config-if)# ipv6 nd ra dns server 2001:DB8:1::1 600
Check your OS for the default…. Most operating systems provide options to use use either one.
Cisco router configured as a client will use EUI-64. More on the router as a client in Lesson 8 when we discuss SLAAC and DHCPv6.
As of now Cisco only supports DNS server advertisement not domain name on IOS XE.
To configure the IPv6 router advertisement of DNS server addresses on an interface, use the ipv6 nd ra dns server command in interface configuration mode. To remove the IPv6 router advertisement of DNS server addresses, use the no form of this command.
ipv6 nd ra dns server ipv6-address seconds
no ipv6 nd ra dns server ipv6-address
Syntax Description
seconds
The amount of time (in seconds) that the Domain Naming System (DNS) server is advertised in an IPv6 router advertisement (RA). The range is from 200 to 4294967295.
Command Default
The DNS server is not advertised in an IPv6 RA.
Command Modes
Interface configuration (config-if)
Command History
Release Modification
Cisco IOS XE Release 3.9S
This command was introduced.
Usage Guidelines
You can use the ipv6 nd ra dns server command to configure up to eight DNS server addresses in an RA.
If you configure a seconds value of zero, the DNS server will no longer be used.
Examples
The following example configures a DNS server with an IPv6 address of 2001:DB8:1::1 to be advertised in an RA with a lifetime of 600 seconds:
Router(config)# interface ethernet 0/0
Router(config-if)# ipv6 nd ra dns server 2001:DB8:1::1 600
Insert FFFE gives us a 64 bit Interface ID
IPv6 64-bit interface IDs are on a 64 bit boundary and accommodate IEEE specification for 64 bit MAC addresses
IEEE has chosen FFFE as a reserved value which can only appear in EUI-64 generated from the an EUI-48 MAC address. IEEE's Guidelines for EUI-64 Registration Authority,
Reason for U/L bit flipped can be found in RFC 4291 IP Version 6 Addressing Architecture
FF-FE – more than likely EUI-64
Link local address is usually the same process
Default gateway – link-local address
Check your OS for the default…. Most operating systems provide options to use use either one.
Documentation states that only an IPv6 router can forward IPv6 packets, however IOS does allow you to configure IPv6 static routes and it forwards IPv6 packets using those routes.
Client router acting as an IPv6 client host.
Ipv6 enable command – necessary to create link-local address, thus enabling it as an IPv6 interface. Remember, a device must have at least a link-local address to be an IPv6 device.
Ipv6 address autoconfig – enables the router to accept and process Router Advertisements on the interface
FE80::1 is the source IPv6 address of the RA
Notice the link-local address also used EUI-64
Client also learned the default gateway (or default route) from R1’s RA
ND
FE80::1 is the source IPv6 address of the RA
