lan ipv6 address assignment setup stateless or stateful

• Artificial Intelligence
• Generative AI
• Cloud Computing
• CPUs and Processors
• Data Center
• Edge Computing
• Enterprise Storage
• Virtualization
• Internet of Things
• Network Management Software
• Network Security
• Enterprise Buyer’s Guides
• United States
• Newsletters
• Foundry Careers
• Terms of Service
• Privacy Policy
• Cookie Policy
• Copyright Notice
• Member Preferences
• About AdChoices
• E-commerce Links
• Your California Privacy Rights

Our Network

• Computerworld

IPv6: How to configure static and DHCP IP addressing and deal with DNS

Ipv6 offers several ways that aren’t possible in ipv4 to assign ip addresses, and dns set-up has differences as well..

As IP technology has matured, the range of devices that the internet protocol supports goes well beyond computers to include cell phones, entertainment systems, and Internet of Things (IoT) devices, which created the need for more IP addresses and the development of IPv6 to provide them.

With more and more device types requiring network connectivity, the demand for addresses in an IPv4-based network is at a premium. It can provide somewhere south of 4,294,967,296 unique addresses. IPv6 , on the other hand, can yield roughly 3.4×10 38 , which should be ample for a very long time.

IPv6 also includes performance enhancements like refined multicasting, stateless address autoconfiguration (SLAAC), simplified headers to streamline router processing, and the option to allow larger packets. Security also gets a potential boost in IPv6 with IPSec, which was initially built for IPv6 and then retrofitted for IPv4.

Dealing with IPv6 includes familiarizing yourself with two important IP concepts: DHCP and DNS. Here are tips on both.

Key IPv6 addressing concepts

IPv6 addressing within a network has a few major differences from IPv4. With IPv4 certain address ranges are reserved for private networks (such as 10.0.0.0/8 or 192.168.0.0/16) and link-local addressing without dynamic host configuration protocol (DHCP) (169.254.0.0/16).

DHCP automatically assigns IP addresses and distributes other information to hosts on a network so they can communicate with other endpoints. At the same time, by assigning active IP addresses only to active devices, DHCP can reuse them to help conserve IPv4 addresses. IPv6 has similar concepts but refines each idea a little further.

Link-local addresses in IPv6 exist on each interface, regardless of whether the interface has an address assigned from DHCP or is configured using another method. Link-local IPv6 addresses have a prefix of fe80::/10 and a 64-bit suffix which can be computed and managed by the host itself without requiring additional networking components. IPv6 hosts can verify the uniqueness of their link-local addresses through a neighbor discovery process, which reaches out to the local network in order to verify that the address is not already in use.

Once a link-local address has been established, the IPv6 host attempts to determine if an IPv6-capable router is available through the use of a router solicitation message. If an IPv6 router is available it will respond with a router advertisement, which includes network configuration information such as a network prefix that is used for automatic address configuration using SLAAC or whether the host should obtain additional configuration information from a DHCPv6 server.

Configuring a Static IPv6 address in Windows

Typical to Windows, there are three ways to configure a static IPv6 address for a network adapter, all of which work in Windows 10 and in both Windows Server 2016 and 2019. The first way uses the classic Control Panel method as follows.

From the Control Panel, navigate to Network and Internet, Network and Sharing Center, and then choose the Change adapter settings link in the left panel. (You can shortcut all the clicking by searching for “View Network Connections” from the Start Menu or the Search bar).

Once you locate the network adapter you wish to configure, you can view the properties and locate the Internet Protocol Version 6 (TCP/IPv6) node and configure the properties for the IPv6 protocol. As with IPv4 you can set the adapter to obtain the IPv6 address automatically or configure your own IPv6 address, subnet, default gateway, and DNS server information. If you need to set multiple IPv6 addresses this can be accomplished by clicking the Advanced button.

The second method of setting a static IP address involves the more modern Settings application. In Settings go to Network & Internet and click the Properties button for the interface you wish to configure. Click the Edit button under IP settings, change the configuration type to Manual, enable IPv6, and populate your settings.

The third way is to use the Windows PowerShell command-line interface. In order to set a static IPv6 address using the New-NetIPAddress cmdlet you will need either the name or the numeric index of the adapter you wish to configure. Both of these values are available using the Get-NetAdapter cmdlet. From an administrative PowerShell prompt enter one of the following commands (on a single line) replacing the details as necessary for your environment:

Managing IPv6 Addressing for a Windows Network

Static IP addresses are generally OK to use when the device is hosting a critical network service that requires retaining a consistent network address, but for general use you’ll want to have a way to automate address configuration.

In an IPv4 network DHCP is the obvious answer for IP configuration and can also provide critical networking details such as the default gateway or DNS-server addresses through DHCP options. IPv6 offers three potential scenarios for managing addressing and network configuration.

SLAAC is a straightforward option assuming your router supports the appropriate router-advertisement messages. DHCP is certainly still in play to handle stateful addressing in the form of DHCPv6. You can also potentially have a hybrid scenario where your router handles addressing, and DHCPv6 simply provides the relevant network-configuration details.

In Windows Server 2016 and 2019, configuring DHCPv6 is extremely straightforward. If your router is configured to handle router advertisements and addressing through SLAAC you can simply manage the IPv6 server options to configure DNS servers or other options. If you prefer to roll with stateful addressing you can add one or more DHCPv6 scopes and configure a prefix, any exclusions, and lease durations. DHCPv6 scopes will maintain a list of leases and their expirations just as an IPv4 scope would, and they also provide an easy path for creating IPv6 reservations from existing leases.

Setting up DNS Name Resolution for IPv6

DNS is incredibly important in an IPv6 network, even moreso than in an IPv4 network because trying to configure connectivity and access resources using only IPv6 addresses is borderline insane. The biggest difference to note in regard to using DNS with IPv6 is that the IPv4 A records, which convert a fully qualified domain name (FQDN) to an IPv4 address, are replaced by AAAA (quad-A) records. All other record types such as CNAME, MX, NS, SOA, and the various DNSSEC-related record types simply reference the FQDN of the AAAA record. Reverse lookup zones, which are used to find a hostname from an IP address, are different in IPv6 simply because they are built on the IP address structure, but the process of creating and using these zones are functionally identical.

The DNS server role in Windows Server supports both IPv4 and IPv6 through a similar set of tools and processes. As with A records, AAAA records can either be created manually for critical systems or the dynamic update process can be leveraged to manage DNS records for the entire enterprise.

AAAA records can be manually created using the DNS console through the same process as A records: Right click the required DNS zone, select the New Host (A or AAAA) option, and populate the Host name and IP address. Dynamic updates are enabled through the DNS console, but most of the work is done by DHCP; the update process is configured within the DHCP console and updates are performed by the DHCP client service on individual hosts. Dynamic updates can also be manually initiated from the command line using the ipconfig command with the /registerdns switch.

Related content

Broadcom changes vmware pricing amid customer backlash and eu questioning, harnessing the power of the ai/5g inflection point, diy or commercial network automation most network teams choose ‘all of the above’, microsoft expands g42 partnership with $1.5 billion investment, newsletter promo module test.

Tim Ferrill is an IT professional and writer living in Southern California. He has covered Windows, Windows Phone, and Windows Server for several publications, including CITEworld and InfoWorld.

More from this author

Tips for building a home lab to prep for network certifications, certifications that can land you a job as a network-automation engineer, free training from 8 top vendors to advance your it career, surviving a mastodon stampede, most popular authors.

Show me more

Leader in gigaom radar sase report for single-vendor sase.

Enterprises struggle with network reliability, security

Who's logging into your Linux servers?

Episode 1: Understanding Cisco’s Converged SDN Transport

Episode 2: Pluggable Optics and the Internet for the Future

Episode 3: Looking Forward: 5G, Digital Transformation, and the Network of the Future

Are unused IPv4 addresses a secret gold mine?

Preparing for a 6G wireless world: Exciting changes coming to the wireless industry

How to calculate factorials in Linux

• Previous : Stateful Autoconfiguration Model
• Next : Duplicate Address Detection Algorithm

When to Use Stateless and Stateful Approaches

The stateless approach is used when a site is not concerned with the exact addresses that hosts use. However, the addresses must be unique. The addresses must also be properly routable. The stateful approach is used when a site requires more precise control over exact address assignments. Stateful and stateless address autoconfiguration can be used simultaneously. The site administrator specifies which type of autoconfiguration to use through the setting of appropriate fields in router advertisement messages.

IPv6 addresses are leased to an interface for a fixed, possibly infinite, length of time. Each address has an associated lifetime that indicates how long the address is bound to an interface. When a lifetime expires, the binding, and address, become invalid and the address can be reassigned to another interface elsewhere. To handle the expiration of address bindings gracefully, an address experiences two distinct phases while the address is assigned to an interface. Initially, an address is preferred, meaning that its use in arbitrary communication is unrestricted. Later, an address becomes deprecated in anticipation that its current interface binding becomes invalid. When the address is in a deprecated state, the use of the address is discouraged, but not strictly forbidden. New communication, for example, the opening of a new TCP connection, should use a preferred address when possible. A deprecated address should be used only by applications that have been using the address. Applications that cannot switch to another address without a service disruption can use a deprecated address.

• © 2010, Oracle Corporation and/or its affiliates

Stack Exchange Network

Stack Exchange network consists of 183 Q&A communities including Stack Overflow , the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Q&A for work

Connect and share knowledge within a single location that is structured and easy to search.

How do I assign IPv6 addresses manually?

So I'm still rather clueless with IPv6, but I wanted to try something with my network today. Currently, I assign IPv4 LAN addresses manually, so that my router is 192.168.0.1 , then my first computer is 192.168.0.2 , and so on.

So far, I haven't been able to figure out how to do this with IPv6. Or is the process completely different that this is not how it would work?

Router is an Archer C4000, and my main system runs Ubuntu 19.04

EDIT: To clarify with how I manually set network IP addresses, my router has a page where I can set an address of my choosing to a MAC address. No configuration is done outside of the router.

• Please edit question and indicate how you assign LAN addesses manually. (On the router only? On your first computer as well?) I suspect you just set a network range on the router, and then addresses are not assigned "manually", but by DHCP from the router. On IPv6 then your router needs to advertise a subnet. On Ubuntu, you can set both IPv4 and IPv6 address manually with ip addr add ... . –  dirkt Sep 10, 2019 at 11:22
• Edited. I'm going to guess then that it is assigned from a range, but then I limit what can be assigned based on MAC addresses. If I'm setting the IP address manually on each device, is there any further configuration that needs to be done (apart from avoiding duplicates), or will the router just accept that device A is going to use its own configured address? –  hiigaran Sep 10, 2019 at 12:00
• If there's a page where you can assign an IPv4 address based on a MAC address, then this is for static addresses assigned via DHCP from the router. IPv6 works differently. While there is DHCPv6, the normal way is to use SLAAC , and let each computer pick an IPv6 address based on the announced subnet prefix.So this page won't help you to assign IPv6 addresses... –  dirkt Sep 10, 2019 at 12:05

2 Answers 2

To clarify with how I manually set network IP addresses, my router has a page where I can set an address of my choosing to a MAC address. No configuration is done outside of the router

This usually isn't called "manual configuration" to avoid confusion (from the LAN hosts' point of view, it is still automatic configuration). The usual terms are "static DHCP lease" or "DHCP reservation".

Overall, the process in IPv6 is usually completely different.

In IPv6 primary address auto-configuration mechanism (SLAAC) is completely stateless: the router does not issue individual addresses; it only periodically advertises the subnet address prefix and each host just combines it with its own chosen suffix. The router cannot limit hosts to just a specific sub-range; in fact the router does not receive any feedback about hosts' chosen address at all.

(Depending on each device's OS, the suffix might be a MAC address in traditional RFC4862 SLAAC; it might be a static hash value in RFC7217; it might be completely random in RFC4941 "Privacy Extensions"; and it might even be a user-provided value if the OS allows that.)

For example, the router advertises 2001:db8:123:456::/64 as the LAN address prefix; client A combines it with its own MAC address and begins using 2001:db8:123:456:6af2:68fe:ff7c:e25c .

That said, DHCP does exist in the IPv6 world and handles address leases in much the same way as IPv4 DHCP does. That means you can create DHCPv6 address pools, you can configure static address leases in DHCPv6, and so on. But not all clients support DHCPv6 at all (e.g. Android does not), so having SLAAC alongside is almost unavoidable.

So if you have a DHCPv6-capable client on a DHCPv6-capable network, chances are it'll have both a nice DHCPv6-assigned address and a longer SLAAC-autoconfigured address.

If I'm setting the IP address manually on each device, is there any further configuration that needs to be done (apart from avoiding duplicates), or will the router just accept that device A is going to use its own configured address?

As you can see above, that's how IPv6 address configuration works anyway .

Your router's manual is found in User Guide and contains for IPv6 only an option for entering a static IPv6 address for the router itself (as received from the ISP).

The section about specifying the IP addresses that the router assigns by MAC address does not say whether they are IPv4 or IPv6, but I think it is highly unlikely that this will work for IPv6. And here is why.

IPv6 is quite unlike IPv4 in the sense that the long IPv6 address is made up of two parts. The first (the prefix) is assigned by the ISP. The second is assigned locally by the router or by each computer and is usually a random value based on the MAC address.

This means that the router does not control the IPv6 prefix which the ISP can change whenever it likes. You can force your computer to use a static IPv6 address, but only if it agrees with the ISP. You may be able to ask the ISP for a static IPv6 address, but that is a bad idea.

The reason it's a bad idea, is that all your devices are visible to the entire Internet by their IPv6 address (unless the router intervenes). Therefore having a fixed IPv6 address just makes tracking you that much easier.

If you wish, you would in Windows set a computer's static IPv6 inside Start > Network > Network and Sharing Center > Change Adapter Setting , right-click on the Ethernet connection IPv6 and choose Properties, right-click "Internet Protocol Version 6 (TCP/IPv6)" and click on Properties, the set "Use the following IPv6 address".

But the fact you can does not mean you should. The only place that static IPv6 addresses makes sense is inside a local network which is not connected to the Internet.

• What about if I wanted to run a web server? I'm constantly traveling for work, and I would love to have access to one of the computers at home which runs 24/7. I'd need to set a static IPv6 for this to work, wouldn't I? –  hiigaran Sep 10, 2019 at 19:23
• A general solution would require an IPv6 dynamic DNS provider. See for that the article dynv6.com: IPv6 dynamic DNS done right . –  harrymc Sep 10, 2019 at 19:29
• @harrymc Help me understand your logic, why would a server in a data center have a static IP but a server at home a dynamic one? In what world does that make any sense? –  Chazy Chaz Jul 29, 2022 at 12:40
• In a world where the ISP attributes to users dynamic IP addresses. –  harrymc Jul 29, 2022 at 12:51

You must log in to answer this question.

Not the answer you're looking for browse other questions tagged networking router ipv6 ..

• The Overflow Blog
• How to succeed as a data engineer without the burnout
• How do you evaluate an LLM? Try an LLM.
• Featured on Meta
• New Focus Styles & Updated Styling for Button Groups
• Upcoming initiatives on Stack Overflow and across the Stack Exchange network
• Google Cloud will be Sponsoring Super User SE

Hot Network Questions

• What is this connector called and are they commonly used?
• On track with my travel agent
• Rotational spectroscopy of diatomic molecules
• Two-sided t-tests: Why do we need to test two-sided if your estimate is telling you in what tail to look already?
• Can we use "It varies a lot" at the beginning of a new paragraph?
• how is my avocado?
• Why is there a year 1 B.C., a year 0, and a year 1 A.D. in NASA’s Five Millennium Canon of Solar Eclipses?
• Can somebody other than the copyright holder enforce the GPL "inherited" by a project? Do they have to?
• Fitting a disk in a non-polygonal region
• What happens if the US President-elect is sent to prison before assuming power?
• Why is 4. Ng5 in the Two Knights not common in current (2024) top-level chess?
• How to select an editor?
• How does HTTP Keepalive handle multiple requests along with EOF from same origin?
• Cryptic Acrostic 7: An Ode to "Mr. Malaprop"
• Is the principle of uniformity of nature an abduction or an analogy?
• What kind of lightbulb is pictured here, having a clear bulb window and 4 yellow vertical rods?
• Military sci-fi about genetically modified soldiers
• Layover in Beijing extended by two days
• Why do protests happen in the light of their apparent futility?
• How was Rome able to conscript and equip 400k soldiers during 2nd Punic War in a pre-industrial society?
• Quantikz not compatible with tikz-cd?
• Situation with Artemov's paper?
• Why did the USA provide a $1 billion Patriot battery but not a $34 million F-16 to Ukraine?
• Monopole antenna impedance measurement

The Cisco Learning Network

Analyzing dhcpv6 stateful and stateless, 4 years ago by ing_percy.

At this time, I would like to share a concise description of the concepts and operation of DHCPv6 by analyzing a laboratory using Cisco Routers and a PC. It is always necessary to mention that the verification of the concepts of Cisco networking must be carried out in the first instance with real equipment. In case the equipment is not available, you can use an emulator like GNS3 and finally you can use a software like Cisco Packet Tracer (the latter is more prone to bugs, especially in more complex topologies).

Previous concepts

We know that in studies about networks, we start with the IPv4 protocol. We learn about static IP addressing on our devices and then about dynamic IP addressing on hosts using the DHCP protocol. It is now reflected in IPv6 networks where global unicast addresses can be configured manually or dynamically. However, for IPv6 networks we have two dynamic allocation methods:

* Stateless address Autoconfiguration (SLAAC)

* Dynamic Host Configuration Protocol for IPv6 (DHCPv6)

If we talk briefly about SLAAC, it is a method by which a host can get an IPv6 global unicast address without a DHCPv6 server. The base of SLAAC is in ICMPv6 which is much more robust than the ICMP of IPv4. Basically, SLAAC uses the following ICMPv6 messages to provide IPv6 addressing:

* Router Solicitation message (RS) : When a client is configured to get its addressing information automatically via SLAAC, it sends an RS message to the router. This message is sent to the multicast address of all IPv6 routers FF02::2. It is the ICMPv6 message type 133.

* Router Advertisement message (RA) : The Routers send RA messages to provide IPv6 addressing information to clients. This message includes the prefix and the prefix length of the local segment. A router sends an RA message periodically (configurable between 4 and 1800 seconds) or in response to an RS message. By default, Cisco routers send RA messages every 200 seconds. RA messages are always sent to the multicast address of all IPv6 nodes FF02::1. It is the ICMPv6 message type 134.

As the name implies, SLAAC is a stateless service. It means there is no server that maintains the network address information. It also does not know which IPv6 addresses are being used and which ones are available. Here the use of DHCPv6 comes into action. The decision of how a client will be able to obtain IPv6 addressing information automatically will depend on what is established within the RA message. For this, we will use two flags which are the Managed address configuration flag (M flag) and the Other configuration flag (O flag).

Using different combinations of the M and O flags, the RA messages establish one of the three addressing options:

* SLAAC (Only using the RA messages)

* DHCPv6 Stateless (RA and DHCPv6 messages)

* DHCPv6 Stateful (Only using the DHCPv6 messages)

Note that although the RA message defines how the client can get an IPv6 address dynamically, the Client's operating system may choose to ignore the RA message and use only the services of a DHCPv6 server.

SLAAC is the default option on Cisco routers. Both the M flag and the O flag are set to 0 (bit) in the RA message. On the client, the IPv6 global unicast address is created by combining the Prefix given by the RA message and the interface ID using EUI-64 or a randomly generated value as occurs in PCs that use the Windows operating system.

If there were previous modifications of the M and O flags in a device, we can reset the interface to operate only with SLAAC with the following configuration in interface mode:

Router (config-if) # no ipv6 nd managed-config-flag

Router (config-if) # no ipv6 nd other-config-flag

DHCPv6 Stateless

The DHCPv6 stateless option informs the client to use the information in the RA message to get the IPv6 addressing, but additional configuration parameters are available from a DHCPv6 server. (for example, IPv6 address of the DNS Server). It is defined with this name because the DHCPv6 server does not maintain any client status information (such as the list of available and assigned IPv6 addresses).

For DHCPv6 Stateless, the O flag is set to 1 (bit) and the M flag is left at the default setting of 0 (bit). The value of the O flag = 1 is used to inform the client that additional configuration information is available from a DHCPv6 server.

To modify the RA message sent from the interface of a router to indicate DHCPv6 Stateless, use the following command:

Router (config-if) # ipv6 nd other-config-flag

DHCPv6 Stateful

This option is the most similar to DHCP that we study in IPv4 networks. In this case, the RA message informs the customer that he should not use the information of its message and all IPv6 addressing information and additional configuration parameters must be obtained from a DHCPv6 Server Stateful. It is defined with this name because the DHCPv6 server maintains IPv6 status information. (List of assigned IPv6 addresses, for example)

The M flag indicates if the DHCPv6 Stateful should be used or not. The O flag is not involved and it can be ignored. The following command is used to change the M flag from 0 to 1 and so, indicate the DHCPv6 Stateful:

Router (config-if) # ipv6 nd managed-config-flag

DHCPV6 - Additional characteristics :

* DHCPv6 has a 4-way negotiation process. Use the following messages:

- REQUEST : A client sends this message to locate DHCPv6 servers using the multicast address FF02::1:2 which is the multicast address of all DHCPv6 Servers.

- ADVERTISE : The servers respond to the Request messages with an Advertise message (unicast) that provides addressing information to the Client.

- REQUEST : The client sends this message to the Server confirming the addresses provided and any other parameters.

- REPLY : The server ends the process with this message containing the assigned IPv6 address and the respective configuration parameters.

* The DHCPv6 Server uses UDP port 547 and DHCPv6 Client uses UDP port 546

* DHCPv6 can be implemented in two forms:

 - Rapid-Commit : the DHCP client gets the configuration parameters from the server through a quick exchange of two messages (Solicit and Reply).

- Normal-commit : the DHCP client exchanges four messages (Solicit, Advertise, Request and Reply).

By default, normal-commit is used.

* In summary a comparison of messages between DHCPv4 and DHCPv6 is shown:

* Consider this summary table with the options for obtaining IPv6 address dynamically using RA messages:

DHCPv6 Stateful Analysis Topology

In this example, we have the following topology with a router and a real PC. Note that the "ipv6 unicast-routing" command is required on router R1 as it is necessary to send ICMPv6 RA messages.

Note that in our configuration of the DHCPv6 pool, a default gateway was not specified, as was the case in IPv4 with the “default-router” command. This happens because the router automatically sent its own local link address (FE80::1) as the default gateway through the RA message we saw in the topology shown.

We can see in the following “show” commands, in first place, the name of the DHCPv6 pool and the configured parameters and second place, we do not see any output since we do not have a DHCPv6 Client that has received an IPv6 address.

The DHCPv6 Unique Identifier (DUID) is used by DHCPv6 to identify the DHCPv6 Client and Server. There is only one DUID per Client and only one DIUD per Server.

In this case, we see other “show” commands where we see the DUID of the DHCPv6 Server and also the effect of having the M flag = 1 that indicates that the Hosts must use DHCPv6 to get a Global Unicast IPv6 address that has the characteristic of being routable addresses.

The initial configuration of the PC is shown:

Applying the “no shutdown” command to the interface G1 of router R1, we will first see the dynamic IPv6 addressing was gotten and the configuration parameters assigned to the PC: 

The PCs that operate in Windows generate by default a random Interface ID value for the auto-configuration of IPv6 with SLAAC instead of the EUI-64 method. However, we can disable through the Windows CMD in Administrator mode with the following command: “netsh interface ipv6 set global randomizeidentifiers=disabled”

Now we will see the outputs of the “show” commands of router R1:

And we have the captures of the DHCPv6 messages using Wireshark:

If we analyze these captures, we see that this information completely coincides with the outputs obtained on Router R1 and the Client (Host)

DHCPv6 Stateless Analysis Topology

Seeing the following “show” command on router R1, which is the DHCP Stateless Server. In this case we see the effect of having the O flag = 1 that indicates that hosts must use SLAAC to get a Global Unicast IPv6 address and for other configuration parameters we must use DHCPv6.

We have the initial configuration of router R2, which is DHCPv6 Client, where we see its IPv6 link-local address, we also see the DUID of the DHCPv6 Client and the MAC address of its interface. Note that part of the DUID value is formed using the MAC address.

Applying the "no shutdown" command to the Interface f0/0 of router R2, we will first see as it gets the IPv6 addressing via SLAAC and the configuration parameters from the DHCPv6 Stateless server:

In the DHCPv6 Stateless Server (R1), we have no control of the IPv6 addresses assigned by SLAAC. The "show" commands prove it:

And we have the capture of the following messages using Wireshark:

DHCPv6 messages

The "Information-request" message is sent by the Client to request the configuration parameters without assigning an IPv6 address to this Client.

We can see the "Reply" message that is sent by the DHCPv6 Stateless Server with the configuration parameters to the Client.

If we analyze these captures, we see that this information completely coincides with the outputs obtained in the DHCP Stateless Server (R1) and the Client (R2)

There is really much more to deepen about IPv6 networks and especially the DHCPv6 protocol. However with this article I want to motivate the compatriots of my country, Peru and the members of this excellent community from all over the world to continue studying, practicing with laboratories and using blogs or videos on the Internet as additional material. Don't study to pass only one exam, but also that it can be part of your working life and enjoy doing what you like to do, which is to be a professional expert in Cisco network technologies. I am sure that if we strive to improve as human beings and as professionals, we can contribute to the development of our countries.

• Author Micheline Murphy to Percy Luis Venturo Huares

You're welcome @Ing_Percy ​  In Central America the situation is also difficult. Definitely, you are right. We have to be patient and I would add to follow the health authorities recommendations.

Stay safe you and your family!

If you encounter a technical issue on the site, please open a support case .

Communities: Chinese | Japanese | Korean

Cisco.com © Copyright 2024 Cisco, Inc. All Rights Reserved. Privacy Statement Terms & Conditions Cookie Policy Trademarks

IPv6 Address Assignment with Stateless Auto-Configuration

The debate over the pros and cons of transitioning to IPv6 continues. Recent articles have agreed that many organizations are IPv6 capable, but because of NAT (Network address translation) borrowing us time against running out of available IP addresses, and the cost associated with upgrading providers’ hardware being a deterrent, IPv6 isn’t as widely used as some experts thought it may be at this time. In any case, it still seems safe to say that IPv6 is an inevitability.

What is IPv6 stateless auto-configuration?

One aspect of IPv6 that seems intriguing is the stateless auto-configuration. IPv6 stateless auto-configuration is a quick-and-easy, plug-and-play method of having a host join an existing IPv6 network.  Stateless auto-configuration process consists of the following:

The IPv6 host generates a link-local address for its interface. A link-local address is formed by taking the well-known link-local prefix of fe80:: and appending an interface identifier . The interface identifier is derived from the host’s MAC address. This link-local address is used solely on the host’s segment and is not routable. An example of a link-local address – fe80::21b:63ff:feab:e6a6 where 21b:63ff:feab:e6a6 was derived from the host’s MAC address using the EUI-64 interface id assignment.

The link-local address is created so the host can use it to send a Router solicitation message to the all-routers multicast group on its local segment, requesting a router inform the host on what network (prefix) it resides.

In response to its Router solicitation request, the host receives a Router Advertisement (RA) containing the prefix. The host creates its IPv6 address by appending its interface identifier to the prefix . An example of a host’s IPv6 address – 2001:DB8::212:7FFF:FEEB:6B40 where 212:7FFF:FEEB:6B40 was derived from the host’s MAC address using the EUI-64 interface id assignment.

Stateless auto-configuration is not a replacement for DHCP (Dynamic Host Configuration Protocol). DHCPv6 will still be used when hosts require addresses for NTP servers, TFTP servers, and other common options. DHCPv6 also offers the audit, tracking and management capabilities if more control of address assignment is required.

To learn more about Cisco training, visit https://go.skyline-ats.com/ciscotraining

Tony DeSimone

Tony DeSimone is a Senior Content Engineer at Skyline ATS with a unique combination of 17 years of certified IT instructor experience coupled with hands-on network administration, course development, and a business background with a degree in management information systems.

Breaking Down the Cisco ENCOR Exam: Infrastructure

Video: what’s the difference between lan, man and wan, related posts, use python pygal to visualize network snmp data, what nbar is and how to use it, how to troubleshoot a network connectivity issue, video: cisco exam taking tips 101, what you need to know about the comptia..., what is static routing and what do we..., top 5 ways to use gre tunneling, breaking down the cisco devnet associate exam: network..., finding the best way to learn about networking, how to run flask in containers.

Stateless address auto-configuration (SLAAC) is a feature that enables IPv6 nodes to auto-generate globally unique addresses (GUA) using Route Advertisements messages sent by a router attached to the local segment. However, SLAAC does not provide DNS and Domain name information. To resolve this problem, the router that is sending the RA messages sets a special flag called O-flag to 1 (O comes from other information). This tells the nodes on the segment that they can contact a stateless DCHPv6 server and get the DNS and Domain name information.

Stateless DHCPv6  is used by nodes to obtain other information , such as a DNS server list and a domain name, that does not require the maintenance of any dynamic state for individual nodes.  A node that uses stateless DHCPv6 must have obtained its IPv6 addresses through some other mechanism usually SLAAC. It is defined in RFC 3736 "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6".

SLAAC with Stateless DCHPv6

Typical dynamic addressing design in IPv6 is to use SLAAC for generating a global unicast address (GUA) and Stateless DHCPv6 for providing DNS and Domain name. Let's look at the example shown in figure 1 and follow the steps PC1 would take to obtain all info it needs.

• Step 1 - When PC1 is connected to the segment, shown in the example, and is configured to use SLAAC, it immediately sends a Router Solicitation message on the network. The message is encapsulated in ICMPv6 type 133 and is destined to the all-routers multicast group FF02::2. The purpose of this message is to discover all neighboring routers.
• The prefix value is set to 2001:1234:A:B::/64
• The MTU value is set to 1500
• The A-flag (Address Autoconfiguration) is set to 1. This tells all neighboring nodes that they can use SLAAC for auto-addressing;
• The O-flag (Other Configuration) is set to 1. This tells all neighboring nodes that they can use Stateless DHCPv6 server to obtain other information such as DNS and Domain name;
• The M-flag (Managed Address Configuration) is set to 0. This indicates that Stateful DHCPv6 is not needed.
• It uses the prefix 2001:1234:A:B::/64 plus the EUI-64 Interface ID to create one or more globally unique addresses.
• The Interface ID could be created from the MAC address (EUI-64) or using a random 64-bit value. By default, Windows hosts use random identifiers. In our example, PC1 generates its address from the prefix + EUI-64 identifier.
• PC1 sets its default gateway to the source of the RA message - the link-local address of Router 1.
• Step 4 - PC1 performs DAD (Duplicate Address Detection) to ensure that the GUA address created using SLAAC is actually unique and is not used by other hosts in the segment. DAD is done by sending a Neighbor Solicitation message, looking for the MAC address of its own IPv6 address. If no host reply back, it means that the address is unique.

At this point, PC1 has a globally unique IPv6 address and a Default Gateway. This means that it has everything it needs to be able to communicate with nodes outside its local network including on the Internet. However, PC1 does not have a DNS server and Domain name, therefore services that require URL-to-IP resolution won't work. Because the O-flag in the Router Advertisement message was set to 1, PC1 knows that there is a stateless DHCPv6 service and it can obtain DNS and domain name from there.

• Step 5 - The RA's O-flag set 1 suggests that additional information is available from a Stateless DHCPv6 server. PC1 sends out a DHCPv6 SOLICIT message destined to the all-DHCPv6 multicast address FF02::1:2.
• Step 6 - Upon receiving this DHCPv6 SOLICIT message, the server replies with a DHCPv6 ADVERTISE indicating that the service is available.
• Step 7 - PC1 then sends out a DHCPv6 INFORMATION-REQUEST message asking for other information.
• Step 8 - The DHCPv6 server responds with a DHCPv6 REPLY message that contains the DNS server list and a domain name.

Implementing SLAAC with Stateless DHCPv6

Implementing SLAAC with stateless DHCPv6 using Cisco routers requires the following steps:

• Setting up a router to send Router Advertisements
• Setting up the O-flag in the RA messages
• Configuring a stateless DHCPv6 server

For this example, we are going to use the topology shown in figure 2. Router 1 is going to send RAs on the segment and Router 2 will act as a stateless DHCP server and provide DNS information. At the end of the example, if everything is successfully configured, PC1 should have a global IPv6 address, a default gateway, DNS server, and domain name configured.

Configuring a Cisco router's SLAAC settings

The first thing we need to configure is to enable the IPv6 unicast routing. If not enabled, the router won't send Router Advertisement messages.

After the IPv6 routing process is enabled, we need to configure a link-local and a global unicast address on the interface that is attached to the link. Using our example topology, that would be interface GigabitEthernet0/0. 

Once the interface is configured with LLA and GUA addresses and enabled, the router starts advertising its presence on the link. The A flag, which tells the hosts that they can use SLAAC, is set to 1 by default and does not need to be configured. However, by default, the Other Configuration flag is set to 0. To tell the hosts to use Stateless DHCPv6 for other information, we need to set the O-flag to 1. This is done using the ipv6 nd other-config-flag command.

Let's look at the output of  show ipv6 interface GigabitEthernet 0/0 command to verify the change in the RA message.

The last two lines of the output of show ipv6 interface gig0/0  indicate how hosts will obtain their addressing information:

• "Hosts use stateless autoconfig for addresses" indicates that the A-flag is set to 1 in the Router Advertisement messages. This tells the neighboring devices that they can use SLAAC for auto-addressing.
• "Hosts use DHCP to obtain other configuration" indicates that the O-flag is set to 1 in the Router Advertisement messages. This tells the neighboring devices that they obtain a DNS server list and a domain name from a Stateless DHCPv6 server.

If we look at a Wireshark capture of the Router Advertisement message, we can see that the O-flag is actually set to 1.

At this point, PC1 has a global unicast address auto-configured using SLAAC.

Configuring a Cisco router as a Stateless DHCPv6 server

Configuring a Cisco router to act as a stateless DHCP server is very straightforward. There are two basic steps:

• Step 1 - Create a DHCPv6 pool name and configuration parameters
• Step 2 - Enable the DHCPv6 pool on an interface.

Let's configure step 1. The first command ipv6 dhcp pool [pool name] creates a DHCPv6 pool and enters into the pool configuration mode. There we define the DNS servers and the domain name and that's it.

In the second step, we enable the DHCPv6 pool on the router's interface attached to the link. With the ipv6 nd ra suppress all command we stop Router 2 from sending Router Advertisements because Router 1 is responsible for the SLAAC configuration and Router 2 is only acting as a stateless DHCP server. 

After the above configuration is set, we can see that Router 2 responds to the DHCPv6 SOLICIT message from PC1. Below you can see Wireshark captures of all messages. Note that the DCHPv6 Solicit message is sent to the all-dhcpv6 servers multicast group FF02::1:2. 

Upon receiving the solicit message from PC1, Router 2 responds with DHCPv6 ADVERTISE. Note that this message is sent to the link-local address of PC1 and is unicast.

After PC1 has discovered that there is a Stateless DHCPv6 server attached to the local segment, it sends the actual request for other information as a DCHPv6 INFORMATION-REQUEST. Note that this message is again sent to the all-dhcpv6 servers multicast group.

Upon receiving the DCHPv6 INFORMATION-REQUEST, Router 2 responds with the requested information. Note that the response is unicast as is sent to PC1's link-local address.

Upon receipt of the DCHPv6 REPLY, PC1 sets the DNS settings to the provided addresses. We can verify that be looking at the Network Connection Details of PC1.

DHCPv6 Rapid-Commit

By default, a client and a DHCPv6 server exchange four messages (SOLICIT, ADVERTISE, REQUEST, and REPLY) before the client gets the requested information. The rapid-commit option reduces this communication to two messages - SOLICIT and REPLY.

The client sends the initial DHCPv6 SOLICIT message with the rapid-commit option set. This tells the server that it wants to speed up the exchange. If the DHCPv6 server is enabled for rapid-commit, it response directly with a DHCPv6 REPLY message, skipping ADVERTISE and INFORMATION-REQUEST. If the DHCP server is not enabled for rapid-commit, it responds with an ADVERTISE message and the process continues with the normal four messages exchange.

Configuring the Rapid-commit option on a Cisco router.

The configuration of the rapid-commit option is pretty basic and straightforward. You include the rapid-commit keyword in the ipv6 dhcp server [poolname] rapid-commit command.

• IPv6 clients use SLAAC to generate their global unicast addresses and obtain their default gateway and other link parameters such as MTU. However, SLAAC does not provide other important information such as DNS and Domain name.
• Routers set the O-flag to 1 in the Router Advertisement messages to inform hosts that other configuration info is available from a Stateless DHCPv6 server .
• When hosts receive RA messages with the O-flag set to 1, they send out a DHCPv6 SOLICIT message to the all-dhcpv6 servers multicast group FF02::1:2.
• If a Stateless DHCPv6 server is available on the segment it responds with a DHCPv6 ADVERTISEMENT message. The client then requests other information such as DNS and domain name with a DHCPv6 INFORMATION-REQUEST and the server provides the requested information with a DHCPv6 REPLY message.
• There is a Rapid-commit option that shortens this exchange from four messages to a rapid two SOLICIT and REPLY .

• Skip to content
• Skip to search
• Skip to footer

IP Addressing Services Configuration Guide, Cisco IOS XE 17.14.x (Catalyst 9600 Switches)

Bias-free language.

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

IP Addressing Services Overview

• IPv6 Client IP Address Learning
• Configuring DHCP
• DHCP Gleaning
• DHCP Options Support
• DHCPv6 Options Support
• DHCPv6 Relay Source Configuration
• Configuring GRE IPv6 Tunnels
• Configuring IPv6 over IPv4 GRE Tunnels
• Configuring GLBP
• Configuring HSRP
• Configuring NHRP
• Configuring Network Address Translation
• Configuring Stateful Network Address Translation 64
• VRRPv3 Protocol Support
• Configuring WCCP
• Configuring Enhanced Object Tracking
• Configuring TCP MSS Adjustment
• Enhanced IPv6 Neighbor Discovery Cache Management
• IPv6 Neighbor Discovery Proxy
• Troubleshooting IP Addressing Services

Chapter: IP Addressing Services Overview

Understanding ipv6, ipv6 addresses, 128-bit wide unicast addresses, dns for ipv6, ipv6 stateless autoconfiguration and duplicate address detection, ipv6 applications, dhcp for ipv6 address assignment, http(s) over ipv6.

This section provides information about IP Addressing Services.

IPv4 users can move to IPv6 and receive services such as end-to-end security, quality of service (QoS), and globally unique addresses. The IPv6 address space reduces the need for private addresses and Network Address Translation (NAT) processing by border routers at network edges.

For information about how Cisco Systems implements IPv6, go to Networking Software (IOS & NX-OS)

For information about IPv6 and other features in this chapter

See the Cisco IOS IPv6 Configuration Library .

Use the Search field on Cisco.com to locate the Cisco IOS software documentation. For example, if you want information about static routes, you can enter Implementing Static Routes for IPv6 in the search field to learn about static routes.

The switch supports only IPv6 unicast addresses. It does not support site-local unicast addresses, or anycast addresses.

The IPv6 128-bit addresses are represented as a series of eight 16-bit hexadecimal fields separated by colons in the format: n:n:n:n:n:n:n:n. This is an example of an IPv6 address:

2031:0000:130F:0000:0000:09C0:080F:130B

For easier implementation, leading zeros in each field are optional. This is the same address without leading zeros:

2031:0:130F:0:0:9C0:80F:130B

You can also use two colons (::) to represent successive hexadecimal fields of zeros, but you can use this short version only once in each address:

2031:0:130F::09C0:080F:130B

For more information about IPv6 address formats, address types, and the IPv6 packet header, see the IPv6 Addressing and Basic Connectivity Configuration Guide of Cisco IOS IPv6 Configuration Library on Cisco.com.

IPv6 Address Formats

IPv6 Address Type: Multicast

IPv6 Address Output Display

Simplified IPv6 Packet Header

The switch supports aggregatable global unicast addresses and link-local unicast addresses. It does not support site-local unicast addresses.

Aggregatable global unicast addresses are IPv6 addresses from the aggregatable global unicast prefix. The address structure enables strict aggregation of routing prefixes and limits the number of routing table entries in the global routing table. These addresses are used on links that are aggregated through organizations and eventually to the Internet service provider.

These addresses are defined by a global routing prefix, a subnet ID, and an interface ID. Current global unicast address allocation uses the range of addresses that start with binary value 001 (2000::/3). Addresses with a prefix of 2000::/3(001) through E000::/3(111) must have 64-bit interface identifiers in the extended unique identifier (EUI)-64 format.

Link local unicast addresses can be automatically configured on any interface by using the link-local prefix FE80::/10(1111 1110 10) and the interface identifier in the modified EUI format. Link-local addresses are used in the neighbor discovery protocol (NDP) and the stateless autoconfiguration process. Nodes on a local link use link-local addresses and do not require globally unique addresses to communicate. IPv6 routers do not forward packets with link-local source or destination addresses to other links.

For more information, see the section about IPv6 unicast addresses in the “Implementing IPv6 Addressing and Basic Connectivity” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

IPv6 supports Domain Name System (DNS) record types in the DNS name-to-address and address-to-name lookup processes. The DNS AAAA resource record types support IPv6 addresses and are equivalent to an A address record in IPv4. The switch supports DNS resolution for IPv4 and IPv6.

The switch uses stateless autoconfiguration to manage link, subnet, and site addressing changes, such as management of host and mobile IP addresses. A host autonomously configures its own link-local address, and booting nodes send router solicitations to request router advertisements for configuring interfaces.

For more information about autoconfiguration and duplicate address detection, see the “Implementing IPv6 Addressing and Basic Connectivity” chapter of Cisco IOS IPv6 Configuration Library on Cisco.com.

The switch has IPv6 support for these applications:

Ping, traceroute, Telnet, and TFTP

Secure Shell (SSH) over an IPv6 transport

HTTP server access over IPv6 transport

DNS resolver for AAAA over IPv4 transport

Cisco Discovery Protocol (CDP) support for IPv6 addresses

For more information about managing these applications, see the Cisco IOS IPv6 Configuration Library on Cisco.com.

DHCPv6 enables DHCP servers to pass configuration parameters, such as IPv6 network addresses, to IPv6 clients. The address assignment feature manages non-duplicate address assignment in the correct prefix based on the network where the host is connected. Assigned addresses can be from one or multiple prefix pools. Additional options, such as default domain and DNS name-server address, can be passed back to the client. Address pools can be assigned for use on a specific interface, on multiple interfaces, or the server can automatically find the appropriate pool.

For configuring DHCP for IPv6, see the Configuring DHCP for IPv6 Address Assignment section.

For more information about configuring the DHCPv6 client, server, or relay agent functions, see the Cisco IOS IPv6 Configuration Library on Cisco.com.

The HTTP client sends requests to both IPv4 and IPv6 HTTP servers, which respond to requests from both IPv4 and IPv6 HTTP clients. URLs with literal IPv6 addresses must be specified in hexadecimal using 16-bit values between colons.

The accept socket call chooses an IPv4 or IPv6 address family. The accept socket is either an IPv4 or IPv6 socket. The listening socket continues to listen for both IPv4 and IPv6 signals that indicate a connection. The IPv6 listening socket is bound to an IPv6 wildcard address.

The underlying TCP/IP stack supports a dual-stack environment. HTTP relies on the TCP/IP stack and the sockets for processing network-layer interactions.

Basic network connectivity ( ping ) must exist between the client and the server hosts before HTTP connections can be made.

For more information, see the “Managing Cisco IOS Applications over IPv6” chapter in the Cisco IOS IPv6 Configuration Library on Cisco.com.

Was this Document Helpful?

Contact Cisco

• (Requires a Cisco Service Contract )

• Trending Now
• Foundational Courses
• Data Science
• Practice Problem
• Machine Learning
• System Design
• DevOps Tutorial
• CCNA Tutorial for Beginners

Basics of Computer Networking

• Network and Communication
• LAN Full Form
• What is OSI Model? - Layers of OSI Model
• TCP/IP Model
• How Data Encapsulation & De-encapsulation Works?

Components of Computer Networking

• NIC Full Form
• What is a network switch, and how does it work?
• What is Network Hub and How it Works?
• Introduction of a Router
• Types of Ethernet Cable

Transport Layer

• Transport Layer responsibilities
• Introduction of Ports in Computers
• What is Transmission Control Protocol (TCP)?
• TCP 3-Way Handshake Process
• User Datagram Protocol (UDP)

Network Layer

• Introduction and IPv4 Datagram Header
• Difference between Unicast, Broadcast and Multicast in Computer Network
• Structure and Types of IP Address

IPv4 Addressing

• What is IPv4?
• Role of Subnet Mask
• Introduction of Classful IP Addressing
• Introduction To Subnetting
• Classless Inter Domain Routing (CIDR)
• Introduction of Variable Length Subnet Mask (VLSM)
• Private IP Addresses in Networking

Data Link Layer

• What is Ethernet?
• What is MAC Address?
• What is an IP Address?

Physical Layer

• Ethernet Frame Format
• What is Power Over Ethernet (POE)?

Cisco Networking Devices

• Network Devices (Hub, Repeater, Bridge, Switch, Router, Gateways and Brouter)
• Collision Detection in CSMA/CD
• Collision Domain and Broadcast Domain in Computer Network
• Difference between layer-2 and layer-3 switches

Life of a Packet

• Working of Domain Name System (DNS) Server
• Configuring DHCP and Web Server in Cisco Packet Tracer
• How Address Resolution Protocol (ARP) works?

Router and Switch Basic Configuration

• Cisco Router basic commands
• Configure IP Address for Interface in Cisco Switches
• Transmission Modes in Computer Networks (Simplex, Half-Duplex and Full-Duplex)
• Link Layer Discovery Protocol (LLDP)
• What is Cisco Discovery Protocol (CDP)?

Cisco Device Management

• What are the different memories used in a CISCO router?
• Router Boot Sequence
• Recovering password in Cisco Routers
• Catalyst Switch Password Reset in Cisco
• Process of Backing Up and Restoring the Cisco IOS
• File Transfer Protocol (FTP)
• Difference between FTP and TFTP
• Backing up Cisco IOS Router image
• Steps Involves in Cisco Router Configuration Backups

Basic Network Trouble shooting

• Troubleshooting Questions on OS and Networking asked in Cloud based Interview
• Internet Control Message Protocol (ICMP)
• What is Ping?
• traceroute Command in Linux with Examples

IPv4 Routing

• What is IP Routing?
• Routing Tables in Computer Network
• Difference between Static and Dynamic Routing
• What is Floating Static Route ?
• How to Add a Static Route to Windows Routing Table?

Dynamic Routing Protocols

• Routing Protocol Code
• Difference between IGRP and BGP
• Administrative Distance (AD) and Autonomous System (AS)
• Configuring a Loopback Interface in Cisco
• What is a Loopback Address?
• What is Passive-Interface Command Behavior in RIP, EIGRP & OSPF?

Interior Gateway Protocols

• Routing Information Protocol (RIP)
• Configuring RIP Default Information Originate in Cisco
• Configuring RIP Versions 1 and 2 in Cisco
• EIGRP fundamentals
• Features of Enhanced Interior Gateway Routing Protocol (EIGRP)
• Types of EIGRP Packet in Computer Network
• How to Configure EIGRP Summarization in Cisco?

Open Shortest Path First(OSPF)

• Open shortest path first (OSPF) router roles and configuration
• Difference between EIGRP and OSPF
• Bandwidth Allocation Control Protocol (BACP)
• Open shortest path first (OSPF) - Set 2
• OSPF Implementation
• Explain OSPF DR/BDR Election?
• Configuring OSPF Passive Interface in Cisco
• Configuring OSPF Default Route Propagation
• Configuring OSPF Maximum Paths
• Configuring OSPF Route Summarization in Cisco
• Configuring OSPF Network Types in Cisco

Virtual Local Area Network(VLAN)

• Three-Layer Hierarchical Model in Cisco
• 2 - Tier And 3 - Tier Architecture in Networking
• Spine-Leaf Architecture
• Virtual LAN (VLAN)
• Configuring and Verifying VLANs in Cisco
• Access and Trunk Ports
• What is ISL(Inter-Switch Link)?
• Inter-Switch Link (ISL) and IEEE 802.1Q
• Access Ports (Data and Voice) in CCNA
• Dynamic Trunking Protocol (DTP)
• VLAN Trunking Protocol (VTP)
• What are the VTP Modes?

Inter-V LAN Routing

• Inter VLAN Routing by Layer 3 Switch
• Configuration of Router on a stick

Dynamic Host Control Protocol(DHCP)

• Difference between DNS and DHCP
• How to Configure DHCP Server on a Cisco Router?
• DHCP Relay Agent in Computer Network
• What is APIPA (Automatic Private IP Addressing)?

Hot Standby Routing Protocol(HSRP)

• Redundant Link problems in Computer Network
• Firsthop Redundancy Protocol
• Hot Standby Router Protocol (HSRP)

Spanning Tree Protocol(STP)

• Introduction of Spanning Tree Protocol (STP)
• What is Bridge in Computer Network - Types, Uses, Functions & Differences
• Working of Spanning Tree Protocol (STP)
• Root Bridge Election in Spanning Tree Protocol
• How Spanning Tree Protocol (STP) Select Designated Port?
• Types of Spanning Tree Protocol (STP)
• Rapid Spanning Tree Protocol
• Configuring Spanning Tree Protocol Portfast

Ethernet Channel

• EtherChannel in Computer Network
• Configure, Verify and Troubleshoot (Layer 2/Layer 3) EtherChannel
• Link Aggregation Control Protocol

Switch Security

• DHCP Snooping
• Wireless Security | Set 1
• Port Security in Computer Network
• Configuring Port Security on Cisco IOS Switch

Access Control List(ACL)

• Standard Access-List
• Static NAT Configuration in Cisco
• Dynamic NAT Configuration in Cisco
• Extended Access-List
• Reflexive Access-List

IPv6 Addressing and Routing

• What is IPv6?
• Internet Protocol version 6 (IPv6)
• IPv6 EUI-64 (Extended Unique Identifier)
• Differences between IPv4 and IPv6
• Global Unicast Address in CCNA
• Link Local Address
• What is IPv6 Address Planning?
• How to Configure IPv6 on CISCO Router?

What is IPv6 Stateless Address Autoconfiguration ?

• RPL (IPv6 Routing protocol)

Wide Area Network

• WAN Full Form
• What is VPN and How It Works?
• Overview of Wireless Wide Area Network (WWAN)
• Multi Protocol Label Switching (MPLS)
• Point-to-Point Protocol (PPP) Suite

Security Concepts

• Types of Cyber Attacks
• Types of Network Firewall
• Introduction of Firewall in Computer Network
• Intrusion Detection System (IDS)
• Intrusion Prevention System (IPS)
• Difference Between Symmetric and Asymmetric Key Encryption
• HTTP Full Form
• Explain the Working of HTTPS
• What is Attack Mitigation?

Network Device Security

• TELNET and SSH in Cisco devices
• How to configure SSH Client in Linux ?
• AAA (Authentication, Authorization and Accounting) configuration (locally)
• RADIUS Protocol
• TACACS+ Protocol
• Network Time Protocol (NTP)
• Configure and Verify NTP Operating in Client and Server Mode

Network Device Management

• What is Syslog server and its working ?
• Command-Line Tools and Utilities For Network Management in Linux
• Simple Network Management Protocol (SNMP)
• Overview of SNMPv3

Wireless Networking

• Wired and Wireless Networking
• What is a Wireless Access Point?
• Cisco Wireless Architecture and AP Modes
• Physical Infrastructure Connections of WLAN Components
• WiFi and its Amendments
• Types of Wireless Security Encryption

The IPv6 addressing scheme is the successor of the IPv4 addressing. The IPv4 addressing scheme used a 32-bit address which translates to over 4 billion unique IPv4 addresses. However, with the expansion of devices that require internet connectivity, this address pool started running out. 

The IPv6 addressing scheme is based on a 128-bit address which translates into a database of about 340 Undecillion routable IPv6 addresses (1 Undecillion = 10 36 ). 

The IPv6 addressing scheme has two ways in which the hosts acquire an IP address.

• DHCPv6 (Stateful)
• SLAAC (Stateless)

The IPv6 Stateless Address Auto-Configuration (SLAAC):

The Stateless Address Auto-Configuration enables hosts to generate a unique routable IPv6 address on their own. The router is configured to follow the IPv6 SLAAC protocol and sends out a Router Advertisement periodically.

The host can also send a Router Solicitation in order to trigger the Routing Advertisement by the router. The Router Solicitation is sent on the address FF02::2 which is the IPv6 multicast address for all the routers.

The Router Advertisement contains the Prefix Information (prefix (network address), prefix length (subnet mask), and default gateway). The host uses this information to generate an IPv6 address (global unicast address or GUA) for itself. The host then employs Duplicate Address Detection to ensure that its address is unique.

The IPv6 SLAAC Configurations:

In order for the router to be able to send the Router Advertisement and essentially for IPv6 SLAAC to function, these configurations must be set using the CLI of the concerned router.

Drawbacks of SLAAC:

• The SLAAC can be used to generate an IPv6 global unicast address but the acquisition of additional information like that of a DNS server has not been standardized. 
• All the additional information may be provided in the Router Advertisement but that is not the accepted standard yet. 
• For this additional information, SLAAC is used in conjunction with DHCP. The SLAAC is responsible for GUA and DHCP for the rest of the information like DNS and others.

Implementation of SLAAC in Cisco Packet Tracer:

To implement the concept practically, we would now configure a router with IPv6 SLAAC with a single host in the Cosco Packet Tracer.  Once the Cisco Packet Tracer is installed, follow the following steps:

Step 1: Form a simple network with a Single Cisco 2911 router and a PC connected via crossover wire, as shown below:

 Single Cisco 2911 router and a PC connected via crossover wire

Step 2: Double click on the router icon and open the CLI prompt, shown below:

Step 3: To configure the Cisco 2911 Router for IPv6 SLAAC, enter the following commands as shown below:

• Enter “no” for the initial configuration dialogue.
• Enter “enable” to enter the Router EXEC mode. (According to configuration 1 in the configuration table)
• Type in “configure terminal” and press enter. (According to configuration 2 in the configuration table)
• Type in “ipv6 unicast-routing” this makes the router routable on the IPv6 address FF02::2. This enables the PC to send out the Router Solicitation. (According to configuration 3 in the configuration table)
• Type in “interface gig 0/0”. The “0/0” part of the command depends on the interface you have connected the router to the PC. (According to configuration 4 in the configuration table)
• Type in “ipv6 address XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX/YY” where “XXXX:….:XXXX” is the IPv6 address of the network and “YY” is the network mask. (According to configuration 5 in the configuration table)
• Type in “no shutdown”. (According to configuration 6 in the configuration table)
• To preview all the changes, type in “do show ipv6 interface gig 0/0”

The Cisco Router 2911 CLI after successfully executing all commands.

As all the configurations have been met, the router is now ready to send out its Router Advertisements. Now close the Router Configuration window.

Step 4: Double click on the PC icon and open the “Desktop” tab:

The PC configuration window

Step 5: Click on the “IP Configuration” option:

The “Desktop” option of the PC configuration.

Step 6: Change the IPv6 Configuration setting from Static to Automatic:

You will now find that the PC generates a Global Unicast Ipv6 Address on its own, with the Default Gateway address and the Link-Local Address from the Router Advertisement.

Simulation Results:

Practical execution of IPv6 SLAAC in the Cisco Packet Tracer is shown in the graphic below.

In this gif, it can be observed how the PC sends the Router Solicitation to the Cisco 2911 Router and the Router replies back with the Router Advertisement.

After the PC receives the Router Advertisement, the PC automatically generates its own IPv6 global unicast address.

Please Login to comment...

Similar reads.

• CCNA IP Addressing
• How to Organize Your Digital Files with Cloud Storage and Automation
• 10 Best Blender Alternatives for 3D Modeling in 2024
• How to Transfer Photos From iPhone to iPhone
• What are Tiktok AI Avatars?
• 30 OOPs Interview Questions and Answers (2024)

Improve your Coding Skills with Practice

What kind of Experience do you want to share?

Stateless autoconfiguration for IPv6

Stateless autoconfiguration for IPv6 is like a “mini-DHCP” server for IPv6. Routers running IPv6 can give the prefix of the network and a gateway address to clients looking for an IPv6 address. IPv6 uses the NDP (Neighbor Discovery Protocol), and one of the things this protocol offers is RS (Route Solicitation and (RA) Router Advertisement messages that help an IPv6 device configure an IPv6 address automatically. Let’s take a look at a configuration example:

Besides configuring an IPv6 address, we must use the ipv6 unicast-routing command to make R2 act like a router. Remember this command since you need it for routing protocols as well.

We need to enable ipv6 address autoconfig on R1 to make sure it generates its own IPv6 address.

We can use debug ipv6 nd to watch the whole process.

We're Sorry, Full Content Access is for Members Only...

If you like to keep on reading, Become a Member Now! Here is why:

• Learn any CCNA, CCNP and CCIE R&S Topic . Explained As Simple As Possible.
• Try for Just $1 . The Best Dollar You’ve Ever Spent on Your Cisco Career!
• Full Access to our 785 Lessons . More Lessons Added Every Week!
• Content created by Rene Molenaar (CCIE #41726)

1984 Sign Ups in the last 30 days

Forum Replies

Good article…

Making it a little more comprehensive will make it a lot better and one of the best learning source especially for starters.

Thanks. I’ll add some more IPv6 stuff in the feature, especially since the new CCNA exams cover much more IPv6 then the previous version.

good article. But I could not get ipv6 address from my neighbor router in gns3 ((

Did you enable the interfaces? It worked fine on a couple of 3600 routers in GNS3.

it works for me. using 7200

40 more replies! Ask a question or join the discussion by visiting our Community Forum