Troubleshoot IPv6 Dynamic Address Assignment with Cisco Router and Microsoft Windows PC

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Updated:April 26, 2018

Document ID:213272

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Introduction

This document describes the available options for dynamic IPv6 address assignment. Troubleshoot of Stateless Address Autoconfiguration (SLAAC) and Dynamic Host Configuration Protocol version 6 (DHCPv6) are covered.

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

IPv6 address architecture
Microsoft Windows Operating System
Basic Wireshark usage

Components Used

The information in this document is based on this hardware/software versions:

Cisco Router with Cisco IOS^®
Microsoft Windows^® 7 PC

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.

Background Information

IPv6 end hosts like computers and laptops that run Microsoft Windows can face a situation where IPv6 address is not dynamically received or shown as expected.

It is suggested to troubleshoot both the Cisco IOS and Microsoft Windows Operating System to to ensure the correct configurations are in place.

Note: Different Operating Systems can behave differently. This depends in how IPv6 has been implemented in their code. This document is intended to give readers an example of the configuration required on Microsoft Windows for IPv6. The configuration on Microsoft Windows presented in this document has been tested in the lab and found to work as expected. The Cisco Technical Assistance Center (TAC) does not support Microsoft Windows configuration assistance.

Methods for IPv6 dynamic address assignment

SLAAC	SLAAC is the native IPv6 method used to provide end hosts with IPv6 address and default gateway information dynamically. It uses Internet Control Message Protocol version 6 (ICMPv6) packets. ICMPv6 Router Solicitation (RS) and ICMPv6 Router Advertisement (RA) packets are exchanged between an IPv6 enabled Router and end hosts. Routers periodically send RA packets (by default every 200 seconds in Cisco IOS) to the local local network or can be requested on demand by end hosts that sends a RS packet. Upon reception of the RA packet, end hosts must derive an IPv6 address (through the use of EUI-64 method for the host portion) and default gateway based on the information included in the packet.
DHCPv6 stateless	DHCPv6 stateless is used to obtain additional configuration parameters (not provided by SLAAC) like DNS, domain name, etc.
DHCPv6 stateful	DHCPv6 stateful database can provide IPv6 addresses to end hosts and keep track of the addresses leased. Information like DNS, domain name, etc, can also be provided by the DHCPv6 stateful method. Default gateway information must still be provided by a Router once it sends RA packets on the local network. This option is the most similar to DHCP for IPv4.

Note: The only way end hosts can dynamically obtain IPv6 default gateway information is from an ICMPv6 Router Advertisement (RA) packet originated by the local Router. DHCPv6 packets currently does not carry any IPv6 default gateway information.

SLAAC

The packet exchange between Router and end host is shown next:

Step 1. End Host initially sends ICMPv6 RS packet.

Step 2. Router replays with ICMPv6 RA packet.

In order to see the exchange, run the free and open source packet analyzer Wireshark on the computer and use these filters:

ICMPv6 RS	icmpv6.type == 133
ICMPv6 RA	icmpv6.nd.ra.flag

End hosts must derive IPv6 address and default gateway information based on information contained in the ICMPv6 RA packet received.

Example of ICMPv6 RA packet obtain with Wireshark:

Frame 187: 118 bytes on wire (944 bits), 118 bytes captured (944 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: IPv6mcast_01 (33:33:00:00:00:01)
Internet Protocol Version 6, Src: fe80::c801:b9ff:fef0:8, Dst: ff02::1          ! Default Gateway.
Internet Control Message Protocol v6
    Type: Router Advertisement (134)
    Code: 0
    Checksum: 0x4ce1 [correct]
    Cur hop limit: 64
    Flags: 0x00
    Router lifetime (s): 1800
    Reachable time (ms): 0
    Retrans timer (ms): 0
    ICMPv6 Option (Source link-layer address : ca:01:b9:f0:00:08)
    ICMPv6 Option (MTU : 1500)
    ICMPv6 Option (Prefix information : 2001:abcd::/64)                         ! Prefix information.

1) ICMPv6 Option (Prefix information) field.

This is the the prefix information that end hosts use for the network portion of their IPv6 address.

The interface identifier (host portion) is created by the end host it uses EUI-64 method.

Microsoft Windows can create the host portion randomly.

2) Internet Protocol Version 6, Source field.

End hosts use the IPv6 source address of the RA packet to configure its IPv6 default gateway.

Troubleshoot SLAAC

From Cisco IOS

Step 1. Ensure the ipv6 unicast-routing command is configured from Global Configuration mode.

Step 2. Ensure the interface in the local network is configured with a valid IPv6 address.

ipv6 unicast-routing             ! Enable IPv6 Routing. In absence of this command
!                                ! the Router does not send any ICMPv6 RA packet.
interface GigabitEthernet0/0/0
 ipv6 address 2001:ABCD::1/64
end

Step 3. Ensure the prefix advertised in the ICMPv6 RA packet is prefix length /64. Otherwise, the end host cannot create any IPv6 address via SLAAC:

ipv6 unicast-routing
!
interface GigabitEthernet0/0/0
 ipv6 address 2001:ABCD::1/64     ! Prefix length defined as /64 on the Router.
end

ICMPv6 RA packet capture:

Frame 187: 118 bytes on wire (944 bits), 118 bytes captured (944 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: IPv6mcast_01 (33:33:00:00:00:01)
Internet Protocol Version 6, Src: fe80::c801:b9ff:fef0:8, Dst: ff02::1
Internet Control Message Protocol v6
    Type: Router Advertisement (134)
    Code: 0
    Checksum: 0x4ce1 [correct]
    Cur hop limit: 64
    Flags: 0x00
    Router lifetime (s): 1800
    Reachable time (ms): 0
    Retrans timer (ms): 0
    ICMPv6 Option (Source link-layer address : ca:01:b9:f0:00:08)
    ICMPv6 Option (MTU : 1500)
    ICMPv6 Option (Prefix information : 2001:abcd::/64)                ! Prefix & prefix lenght information.

Step 4. The command debug ipv6 nd shows in real time the reception of the ICMPv6 RS packet and the advertisement of the ICMPv6 RA on the local network.

Router# debug ipv6 nd
  ICMP Neighbor Discovery events debugging is on
Router#

Router# show logging | include RS
 ICMPv6-ND: Received RS on GigabitEthernet0/0/0 from FE80::5850:6D61:1FB:EF3A
R1#

Router# show logging | include RA
 ICMPv6-ND: Sending solicited RA on GigabitEthernet0/0/0
 ICMPv6-ND: Request to send RA for FE80::C801:EFFF:FE5A:8
 ICMPv6-ND: Setup RA from FE80::C801:EFFF:FE5A:8 to FF02::1 on GigabitEthernet0/0/0
Router#

From Microsoft Windows PC

Step 1. Ensure the end host receives the RA packet.

This can be done with Wireshark and a capture with icmpv6.nd.ra.flag filter.

Step 2. Use the command ipconfig to verify the IPv6 address.

If the IPv6 address is still not displayed, follow the next steps.

Step 3. Ensure that the network adapter has Internet Protocol version 6 (TCP/IPv6) checkbox activated on the Windows computer.

On Windows, you can find this configuration here:

Step 1. Navigate to Control Panel > Network and Sharing Center > Change adapter settings

Step 2. Right click on the network adapter of your selection > Properties

The network adapter does not have Internet Protocol version 6 (TCP/IPv6) enabled when you get the next message in Windows Command Prompt (CMD) with the command netsh interface ipv6 show interface "Local Area Connection".

Note: In the this command, you can replace Local Area Connection with the name of the network adapter Microsoft Windows uses to connect to the network.

Tip: To open a Command Prompt. Press Windows + R in your keyboard to open Run box. Run the command cmd and press OK

Step 3. Ensure the Router Discovery parameter is set to enabled.

Run the command netsh interface ipv6 show interface "Local Area Connection" in CMD.

Microsoft Windows can ignore the content of the received ICMPv6 RA packet when the Router Discovery parameter is set to disabled. This can cause Microsoft Windows not generate any IPv6 address.

Use this command to to enable Router Discovery:

C:\> netsh interface ipv6 set interface "Local Area Connection" routerdiscovery=enabled

Step 4. Ensure the Advertising parameter is set to disabled.

Run the command netsh interface ipv6 show interface "Local Area Connection" in CMD.

Microsoft Windows can ignore the content of the received ICMPv6 RA packet if the Advertising parameter is set to enabled.

The Advertising parameter enabled causes Microsoft Windows behave as IPv6 Router, generate and send its own ICMPv6 RA packets to the local network.

The default state of the Advertising parameter must be disabled.

Use this command to disable Advertising:

C:\> netsh interface ipv6 set interface "Local Area Connection" advertise=disabled

DHCPv6 Stateless

End hosts can request additional IPv6 configuration parameters like DNS, domain name, etc, with the use of DHCPv6 stateless. For this, the ICMPv6 RA packet must have the Other Configuration flag (O bit) set.

The Router sets the O flag when the ipv6 nd other-config-flag command is present in Cisco IOS interface configuration mode.

Router#

interface GigabitEthernet0/0/0
 ipv6 address 2001:ABCD::1/64
 ipv6 nd other-config-flag
!

The packet exchange between the Router and end hosts occurs as shown in the image.

Step 1. End Host initially sends ICMPv6 RS

Step 2. Router replays with ICMPv6 RA and include the O flag set

Step 3. End Host sends DHCPv6 Informaton-request

Step 4. Router replays with DHCPv6 Reply

ICMPv6 RA with Other Configuration flag set packet capture:

Frame 9: 118 bytes on wire (944 bits), 118 bytes captured (944 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: IPv6mcast_01 (33:33:00:00:00:01)
Internet Protocol Version 6, Src: fe80::c801:b9ff:fef0:8, Dst: ff02::1
Internet Control Message Protocol v6
    Type: Router Advertisement (134)
    Code: 0
    Checksum: 0x4ca1 [correct]
    Cur hop limit: 64
    Flags: 0x40
        0... .... = Managed address configuration: Not set
        .1.. .... = Other configuration: Set        ! Cisco IOS command ipv6 nd other-config-flag sets the O flag
        ..0. .... = Home Agent: Not set
        ...0 0... = Prf (Default Router Preference): Medium (0)
        .... .0.. = Proxy: Not set
        .... ..0. = Reserved: 0
    Router lifetime (s): 1800
    Reachable time (ms): 0
    Retrans timer (ms): 0
    ICMPv6 Option (Source link-layer address : ca:01:b9:f0:00:08)
    ICMPv6 Option (MTU : 1500)
    ICMPv6 Option (Prefix information : 2001:abcd::/64)

On Wireshark, use the dhcpv6 filter to show the exchange of DHCPv6 packets:

Source                  Destination     Protocol  Length  Info
PC IPv6 link local	ff02::1:2	DHCPv6	  120	  Information-request XID: 0x8018f9 CID: 000100011f3e8772000c29806ccc 

Frame 3884: 120 bytes on wire (960 bits), 120 bytes captured (960 bits) on interface 0
Ethernet II, Src: Vmware_80:6c:cc (00:0c:29:80:6c:cc), Dst: IPv6mcast_01:00:02 (33:33:00:01:00:02)
Internet Protocol Version 6, Src: PC IPv6 link local (fe80::5850:6d61:1fb:ef3a), Dst: ff02::1:2 (ff02::1:2)
User Datagram Protocol, Src Port: 546 (546), Dst Port: 547 (547)
DHCPv6
    Message type: Information-request (11)
    Transaction ID: 0x8018f9
    Elapsed time
    Client Identifier
    Vendor Class
    Option Request


Source                  Destination             Protocol  Length  Info
Router IPv6 link local	PC IPv6 link local	DHCPv6	  136	  Reply XID: 0x8018f9 CID: 000100011f3e8772000c29806ccc 

Frame 3887: 136 bytes on wire (1088 bits), 136 bytes captured (1088 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: Vmware_80:6c:cc (00:0c:29:80:6c:cc)
Internet Protocol Version 6, Src: Router IPv6 link local (fe80::c801:b9ff:fef0:8), Dst: PC IPv6 link local (fe80::5850:6d61:1fb:ef3a)
User Datagram Protocol, Src Port: 547 (547), Dst Port: 546 (546)
DHCPv6
    Message type: Reply (7)
    Transaction ID: 0x8018f9
    Server Identifier
    Client Identifier
    DNS recursive name server
    Domain Search List

DHCPv6 Stateless Server on Cisco IOS Configuration Example

From Cisco IOS

This example shows the configuration of DHCPv6 Stateless Server in Cisco IOS.

Step 1. From Global configuration mode run the command ipv6 dhcp pool NAME.

Step 2. Use the dns-server and doman-name sub-commands to define the parameters that are sent to the end hosts via DHCPv6.

Step 3. Apply the pool defined in the interface configuration mode with the command ipv6 dhcp server NAME.

Step 4. Add the command ipv6 nd other-config-flag in the interface configuration mode.

ipv6 unicast-routing
!
ipv6 dhcp pool LAN_POOL
 dns-server 2001:4860:4860::8888
 domain-name lab-test.net
!
interface GigabitEthernet0/0/0
 ipv6 address 2001:ABCD::1/64
 ipv6 nd other-config-flag        ! Sets the Other Configuration flag in the RA packet.
 ipv6 dhcp server LAN_POOL
!

In order to verify the configuration on Cisco IOS is correct, use these commands:

Step 1. show ipv6 dhcp pool must confirm the parameter applied in the configuration.

Step 2. show ipv6 dhcp binding must not show any information since DHCPv6 stateless does not keep track of IPv6 clients.

Step 3. show ipv6 dhcp interface must show the pool is applied to the interface in the local network.

Router#show ipv6 dhcp pool
DHCPv6 pool: LAN_POOL
  DNS server: 2001:4860:4860::8888
  Domain name: lab-test.net
  Active clients: 0         ! DHCPv6 Stateless does not keep track of IPv6 clients.
Router#


Router#show ipv6 dhcp binding
Router#


Router#show ipv6 dhcp interface
FastEthernet0/0 is in server mode
  Using pool: LAN_POOL
  Preference value: 0
  Hint from client: ignored
  Rapid-Commit: disabled
Router#

The command debug ipv6 dhcp must show the message exchange between the Router and end host:

Router#debug ipv6 dhcp
   IPv6 DHCP debugging is on

IPv6 DHCP: Received INFORMATION-REQUEST from FE80::5850:6D61:1FB:EF3A on FastEthernet0/0
IPv6 DHCP: Option VENDOR-CLASS(16) is not processed
IPv6 DHCP: Using interface pool LAN_POOL
IPv6 DHCP: Source Address from SAS FE80::C801:B9FF:FEF0:8
IPv6 DHCP: Sending REPLY to FE80::5850:6D61:1FB:EF3A on FastEthernet0/0
Router#

From Microsoft Windows

From the command prompt, run the command ipconfig /all to ensure Microsoft Windows has received DNS Server information and domain name:

C:\Users\ >ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : MY-LAPTOP
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : lab-test.net

Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . : lab-test.net
   Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
   Physical Address. . . . . . . . . : 00-0C-29-80-6C-CC
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv6 Address. . . . . . . . . . . : 2001:abcd::5850:6d61:1fb:ef3a(Preferred)

   Temporary IPv6 Address. . . . . . : 2001:abcd::7151:b553:1a0a:80bb(Preferred)

   Link-local IPv6 Address . . . . . : fe80::5850:6d61:1fb:ef3a%11(Preferred)
   Default Gateway . . . . . . . . . : fe80::c801:b9ff:fef0:8%11
   DHCPv6 IAID . . . . . . . . . . . : 234884137
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1F-3E-87-72-00-0C-29-80-6C-CC

   DNS Servers . . . . . . . . . . . : 2001:4860:4860::8888
   NetBIOS over Tcpip. . . . . . . . : Disabled
   Connection-specific DNS Suffix Search List :
                                       lab-test.net

C:\Users\ >

DHCPv6 Stateful

End hosts can request IPv6 address and additional parameters with the use of DHCPv6 Stateful. For this, the ICMPv6 RA packet must have the Managed Address Configuration flag (M flag) set.

The Router sets the M flag when the ipv6 nd managed-config-flag command is present in Cisco IOS interface configuration mode.

Router#

interface GigabitEthernet0/0/0
 ipv6 address 2001:ABCD::1/64
 ipv6 nd managed-config-flag
!

The packet exchange between the Router and end hosts occurs as shown in the image.

Step 1. End Host initially sends ICMPv6 RS.

Step 2. Router replays with ICMPv6 RA with M flag set.

Step 3. End Host send DHCPv6 Solicit.

Step 4. Router replays with DHCPv6 Advertise.

Step 5. End Host sends DHCPv6 Request.

Step 6. Router replays with DHCPv6 Reply.

ICMPv6 RA with Managed address configuration flag set packet capture:

Frame 1190: 118 bytes on wire (944 bits), 118 bytes captured (944 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: IPv6mcast_01 (33:33:00:00:00:01)
Internet Protocol Version 6, Src: Router IPv6 link local (fe80::c801:b9ff:fef0:8), Dst: ff02::1 (ff02::1)
Internet Control Message Protocol v6
    Type: Router Advertisement (134)
    Code: 0
    Checksum: 0x0642 [correct]
    Cur hop limit: 64
    Flags: 0x80
        1... .... = Managed address configuration: Set
        .0.. .... = Other configuration: Not set
        ..0. .... = Home Agent: Not set
        ...0 0... = Prf (Default Router Preference): Medium (0)
        .... .0.. = Proxy: Not set
        .... ..0. = Reserved: 0
    Router lifetime (s): 1800
    Reachable time (ms): 0
    Retrans timer (ms): 0
    ICMPv6 Option (Source link-layer address : ca:01:b9:f0:00:08)
    ICMPv6 Option (MTU : 1500)
    ICMPv6 Option (Prefix information : 2001:abcd::/64)
    Type: Prefix information (3)
    Length: 4 (32 bytes)
    Prefix Length: 64
    Flag: 0x80
        1... .... = On-link flag(L): Set
        .0.. .... = Autonomous address-configuration flag(A): Not set
        ..0. .... = Router address flag(R): Not set
        ...0 0000 = Reserved: 0
    Valid Lifetime: 1800
    Preferred Lifetime: 1800
    Reserved
    Prefix: 2001:abcd:: (2001:abcd::)

In Wireshark, use the dhcpv6 filter to show the exchange of DHCPv6 packets:

Source              Destination   Protocol  Length  Info
PC IPv6 link local  ff02::1:2	  DHCPv6       157  Solicit XID: 0x328090 CID: 000100011f3e8772000c29806ccc 

Frame 965: 157 bytes on wire (1256 bits), 157 bytes captured (1256 bits) on interface 0
Ethernet II, Src: Vmware_80:6c:cc (00:0c:29:80:6c:cc), Dst: IPv6mcast_01:00:02 (33:33:00:01:00:02)
Internet Protocol Version 6, Src: PC IPv6 link local (fe80::5850:6d61:1fb:ef3a), Dst: ff02::1:2 (ff02::1:2)
User Datagram Protocol, Src Port: 546 (546), Dst Port: 547 (547)
DHCPv6
    Message type: Solicit (1)
    Transaction ID: 0x328090
    Elapsed time
    Client Identifier
    Identity Association for Non-temporary Address
    Fully Qualified Domain Name
    Vendor Class
    Option Request


Source                  Destination         Protocol  Length  Info
Router IPv6 link local	PC IPv6 link local  DHCPv6    180     Advertise XID: 0x328090 CID: 000100011f3e8772000c29806ccc IAA: 2001:abcd::70a1:36a7:3e72:fa95 

Frame 966: 180 bytes on wire (1440 bits), 180 bytes captured (1440 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: Vmware_80:6c:cc (00:0c:29:80:6c:cc)
Internet Protocol Version 6, Src: Router IPv6 link local (fe80::c801:b9ff:fef0:8), Dst: PC IPv6 link local (fe80::5850:6d61:1fb:ef3a)
User Datagram Protocol, Src Port: 547 (547), Dst Port: 546 (546)
DHCPv6
    Message type: Advertise (2)
    Transaction ID: 0x328090
    Server Identifier
    Client Identifier
    Identity Association for Non-temporary Address
    DNS recursive name server
    Domain Search List


Source              Destination  Protocol  Length  Info
PC IPv6 link local  ff02::1:2	 DHCPv6	      199  Request XID: 0x328090 CID: 000100011f3e8772000c29806ccc IAA: 2001:abcd::70a1:36a7:3e72:fa95 

Frame 967: 199 bytes on wire (1592 bits), 199 bytes captured (1592 bits) on interface 0
Ethernet II, Src: Vmware_80:6c:cc (00:0c:29:80:6c:cc), Dst: IPv6mcast_01:00:02 (33:33:00:01:00:02)
Internet Protocol Version 6, Src: PC IPv6 link local (fe80::5850:6d61:1fb:ef3a), Dst: ff02::1:2 (ff02::1:2)
User Datagram Protocol, Src Port: 546 (546), Dst Port: 547 (547)
DHCPv6
    Message type: Request (3)
    Transaction ID: 0x328090
    Elapsed time
    Client Identifier
    Server Identifier
    Identity Association for Non-temporary Address
    Fully Qualified Domain Name
    Vendor Class
    Option Request


Source                  Destination          Protocol  Length  Info
Router IPv6 link local	PC IPv6 link local   DHCPv6    180     Reply XID: 0x328090 CID: 000100011f3e8772000c29806ccc IAA: 2001:abcd::70a1:36a7:3e72:fa95 

Frame 968: 180 bytes on wire (1440 bits), 180 bytes captured (1440 bits) on interface 0
Ethernet II, Src: ca:01:b9:f0:00:08 (ca:01:b9:f0:00:08), Dst: Vmware_80:6c:cc (00:0c:29:80:6c:cc)
Internet Protocol Version 6, Src: Router IPv6 link local (fe80::c801:b9ff:fef0:8), Dst: PC IPv6 link local (fe80::5850:6d61:1fb:ef3a)
User Datagram Protocol, Src Port: 547 (547), Dst Port: 546 (546)
DHCPv6
    Message type: Reply (7)
    Transaction ID: 0x328090
    Server Identifier
    Client Identifier
    Identity Association for Non-temporary Address
    DNS recursive name server
    Domain Search List

DHCPv6 Stateful Server on Cisco IOS Configuration Example

From Cisco IOS

This example shows the configuration of DHCPv6 Stateful Server in Cisco IOS.

Step 1. From Global configuration mode run the command ipv6 dhcp pool NAME.

Step 2. Use address prefix, dns-server and doman-name sub-commands to define the parameters that are sent to the end hosts via DHCPv6.

Step 3. Apply the pool defined in the interface configuration mode with the command ipv6 dhcp server NAME.

Step 4. Add the command ipv6 nd managed-config-flag in the interface configuration mode.

Step 5. Add the command ipv6 nd prefix default 1800 1800 no-autoconfig in the interface configuration mode to disable the Autonomous address-configuration(A) flag in the ICMPv6 RA packet.

Note: End hosts can configure for itself two different IPv6 addresses when you use the DHCPv6 Stateful Server approach. The first one with the information contained in the ICMPv6 RA packet. The second one with the information contained in the DHCPv6 packet. To avoid this, the ICMPv6 RA packet can disable the A flag to instruct end hosts to not generate IPv6 address based on the information contained in it.

Note: Prefix information can be removed from the content of the ICMPv6 RA packet with the command ipv6 nd prefix default no-advertise in interface configuration mode.

ipv6 unicast-routing
!
ipv6 dhcp pool LAN_POOL
 address prefix 2001:ABCD::/64    ! Includes the IPv6 prefix in the DHCPv6 packet exchange.
 dns-server 2001:4860:4860::8888
 domain-name lab-test.net
!
interface GigabitEthernet0/0/0
 ipv6 address 2001:ABCD::/64 eui-64
 ipv6 nd prefix default 1800 1800 no-autoconfig ! Disables the Autonomous address-configuration(A) flag in the ICMPv6 RA packet.
 ipv6 nd managed-config-flag                    ! Sets the Managed address configuration flag in the ICMPv6 RA packet.
 ipv6 dhcp server LAN_POOL
end

In order to verify the configuration on Cisco IOS is correct, use these commands:

Step 1. show ipv6 dhcp pool must confirm the parameter applied in the configuration.

Step 2. show ipv6 dhcp binding must information for the IPv6 addresses leased to end hosts.

Step 3. show ipv6 dhcp interface must show the pool is applied to the interface in the local network.

Router#show ipv6 dhcp pool 
DHCPv6 pool: LAN_POOL
  Address allocation prefix: 2001:ABCD::/64 valid 172800 preferred 86400 (1 in use, 0 conflicts)
  DNS server: 2001:4860:4860::8888
  Domain name: lab-test.net
  Active clients: 1
Router#


Router#show ipv6 dhcp binding 
Client: FE80::5850:6D61:1FB:EF3A 
  DUID: 000100011F3E8772000C29806CCC
  Username : unassigned
  IA NA: IA ID 0x0E000C29, T1 43200, T2 69120
    Address: 2001:ABCD::3DD4:77BB:E035:9375
            preferred lifetime 86400, valid lifetime 172800
            expires at Dec 28 2016 10:44 PM (172488 seconds)
Router#


Router#show ipv6 dhcp interface 
FastEthernet0/0 is in server mode
  Using pool: LAN_POOL
  Preference value: 0
  Hint from client: ignored
  Rapid-Commit: disabled
Router#

The command debug ipv6 dhcp must show the message exchange between the Router and end host:

Router#debug ipv6 dhcp 
   IPv6 DHCP debugging is on
Router#

IPv6 DHCP: Received SOLICIT from FE80::5850:6D61:1FB:EF3A on FastEthernet0/0
IPv6 DHCP: Option UNKNOWN(39) is not processed
IPv6 DHCP: Option VENDOR-CLASS(16) is not processed
IPv6 DHCP: Using interface pool LAN_POOL
IPv6 DHCP: Creating binding for FE80::5850:6D61:1FB:EF3A in pool LAN_POOL
IPv6 DHCP: Binding for IA_NA 0E000C29 not found
IPv6 DHCP: Allocating IA_NA 0E000C29 in binding for FE80::5850:6D61:1FB:EF3A
IPv6 DHCP: Looking up pool 2001:ABCD::/64 entry with username '000100011F3E8772000C29806CCC0E000C29'
IPv6 DHCP: Poolentry for user not found
IPv6 DHCP: Allocated new address 2001:ABCD::D9F7:61C:D803:DCF1
IPv6 DHCP: Allocating address 2001:ABCD::D9F7:61C:D803:DCF1 in binding for FE80::5850:6D61:1FB:EF3A, IAID 0E000C29
IPv6 DHCP: Updating binding address entry for address 2001:ABCD::D9F7:61C:D803:DCF1
IPv6 DHCP: Setting timer on 2001:ABCD::D9F7:61C:D803:DCF1 for 60 seconds
IPv6 DHCP: Source Address from SAS FE80::C801:B9FF:FEF0:8
IPv6 DHCP: Sending ADVERTISE to FE80::5850:6D61:1FB:EF3A on FastEthernet0/0
IPv6 DHCP: Received REQUEST from FE80::5850:6D61:1FB:EF3A on FastEthernet0/0
IPv6 DHCP: Option UNKNOWN(39) is not processed
IPv6 DHCP: Option VENDOR-CLASS(16) is not processed
IPv6 DHCP: Using interface pool LAN_POOL
IPv6 DHCP: Looking up pool 2001:ABCD::/64 entry with username '000100011F3E8772000C29806CCC0E000C29'
IPv6 DHCP: Poolentry for user found
IPv6 DHCP: Found address 2001:ABCD::D9F7:61C:D803:DCF1 in binding for FE80::5850:6D61:1FB:EF3A, IAID 0E000C29
IPv6 DHCP: Updating binding address entry for address 2001:ABCD::D9F7:61C:D803:DCF1
IPv6 DHCP: Setting timer on 2001:ABCD::D9F7:61C:D803:DCF1 for 172800 seconds
IPv6 DHCP: Source Address from SAS FE80::C801:B9FF:FEF0:8
IPv6 DHCP: Sending REPLY to FE80::5850:6D61:1FB:EF3A on FastEthernet0/0
Router#

From Microsoft Windows

Run the command ipconfig /all to ensure Microsoft Windows has received IPv6 address, default gateway, DNS Server information and domain name:

C:\Users\ >ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : MY-LAPTOP
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : lab-test.net

Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . : lab-test.net
   Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
   Physical Address. . . . . . . . . : 00-0C-29-80-6C-CC
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv6 Address. . . . . . . . . . . : 2001:abcd::3dd4:77bb:e035:9375(Preferred)

   Lease Obtained. . . . . . . . . . : Sunday, January 01, 2017 4:47:02 PM
   Lease Expires . . . . . . . . . . : Tuesday, January 03, 2017 4:47:02 PM
   Link-local IPv6 Address . . . . . : fe80::5850:6d61:1fb:ef3a%11(Preferred)
   Default Gateway . . . . . . . . . : fe80::c801:b9ff:fef0:8%11
   DHCPv6 IAID . . . . . . . . . . . : 234884137
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-1F-3E-87-72-00-0C-29-80-6C-CC

   DNS Servers . . . . . . . . . . . : 2001:4860:4860::8888
   NetBIOS over Tcpip. . . . . . . . : Disabled
   Connection-specific DNS Suffix Search List :
                                       lab-test.net

C:\Users\ >

Disable Windows Randomly Generated Interface ID

Microsoft Windows generates by default a random interface ID for auto-configured IPv6 address (with SLAAC) rather than use EUI-64 method.

C:\Users\   >ipconfig

Windows IP Configuration


Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . :
   IPv6 Address. . . . . . . . . . . : 2001:abcd::5850:6d61:1fb:ef3a   ! Randomly generated interface ID.
   Temporary IPv6 Address. . . . . . : 2001:abcd::8d1:8bbb:14e4:658e
   Link-local IPv6 Address . . . . . : fe80::5850:6d61:1fb:ef3a%11
   Default Gateway . . . . . . . . . : fe80::c801:b9ff:fef0:8%11

This behavior can be changed to make Windows to use the EUI-64 process.

netsh interface ipv6 set global randomizeidentifiers=disabled

You can see now see the Interface ID was generated with the use of the EUI-64 process.

C:\Users\   >ipconfig

Windows IP Configuration


Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . :
   IPv6 Address. . . . . . . . . . . : 2001:abcd::20c:29ff:fe80:6ccc   ! Interface ID now generated by EUI-64 method.
   Temporary IPv6 Address. . . . . . : 2001:abcd::9818:d729:fadb:8812
   Link-local IPv6 Address . . . . . : fe80::20c:29ff:fe80:6ccc%11
   Default Gateway . . . . . . . . . : fe80::c801:b9ff:fef0:8%11

To use the random interface ID process again you can run the command:

netsh interface ipv6 set global randomizeidentifiers=enabled

Disable Windows Temporary IPv6 address

For security reasons, Windows can temporarily create IPv6 addresses and use those as a source for outbound connections.

This can create confusion in scenarios when the expectation is that end hosts use certain IPv6 address to source the communication like when Firewall rules are defined in the network.

The Temporary IPv6 Address is because of Windows implementation of RFC 4941.

C:\Users\   >ipconfig

Windows IP Configuration


Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . :
   IPv6 Address. . . . . . . . . . . : 2001:abcd::5850:6d61:1fb:ef3a
   Temporary IPv6 Address. . . . . . : 2001:abcd::8d1:8bbb:14e4:658e
   Link-local IPv6 Address . . . . . : fe80::5850:6d61:1fb:ef3a%11
   Default Gateway . . . . . . . . . : fe80::c801:b9ff:fef0:8%11



C:\Users\   >netsh interface ipv6 show privacy
Querying active state...

Temporary Address Parameters
---------------------------------------------
Use Temporary Addresses             : enabled
Duplicate Address Detection Attempts: 5
Maximum Valid Lifetime              : 7d
Maximum Preferred Lifetime          : 1d
Regenerate Time                     : 5s
Maximum Random Time                 : 10m
Random Time                         : 0s


C:\Users\Gus>

To disable the automatic creation of the Temporary IPv6 Address run the command:

netsh interface ipv6 set privacy state=disabled

With the command applied, the outputs show:

C:\Users\   >ipconfig

Windows IP Configuration


Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . :
   IPv6 Address. . . . . . . . . . . : 2001:abcd::5850:6d61:1fb:ef3a
   Link-local IPv6 Address . . . . . : fe80::5850:6d61:1fb:ef3a%11
   Default Gateway . . . . . . . . . : fe80::c801:b9ff:fef0:8%11


C:\Users\   >netsh interface ipv6 show privacy
Querying active state...

Temporary Address Parameters
---------------------------------------------
Use Temporary Addresses             : disabled
Duplicate Address Detection Attempts: 5
Maximum Valid Lifetime              : 7d
Maximum Preferred Lifetime          : 1d
Regenerate Time                     : 5s
Maximum Random Time                 : 10m
Random Time                         : 0s

To use Temporary IPv6 Address again you can run the command:

netsh interface ipv6 set privacy state=enable

IPv6 dynamic address assignment offers more options than DHCP in IPv4. It is necessary to know the main configuration points and what to check when the process does not complete as expected. The basic configuration commands are offered for this on Cisco IOS and Microsoft Windows for a complete view of the overall process.

Related Information

Contributed by Cisco Engineers

Hector Gustavo Serrano Gutierrez
Cisco TAC Engineer

Troubleshoot IPv6 Dynamic Address Assignment with Cisco Router and Microsoft Windows PC

Available Languages

Bias-Free Language

Contents

Introduction

Prerequisites

Requirements

Components Used

Background Information

Methods for IPv6 dynamic address assignment

SLAAC

Troubleshoot SLAAC

From Cisco IOS

From Microsoft Windows PC

DHCPv6 Stateless

DHCPv6 Stateless Server on Cisco IOS Configuration Example

From Cisco IOS

From Microsoft Windows

DHCPv6 Stateful

DHCPv6 Stateful Server on Cisco IOS Configuration Example

From Cisco IOS

From Microsoft Windows

Disable Windows Randomly Generated Interface ID

Disable Windows Temporary IPv6 address

Related Information

Contributed by Cisco Engineers

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