How to configure IPv6?
To obtain the IPv6 configuration for a computer:
- Click Start, point to All Programs, point to Accessories, and then click Command Prompt.
- At the command prompt type, the following command, and then press ENTER: Console netsh interface ipv6 show interface
- At the command prompt, type ping ::1 to locate the loopback address. ...
What are the basics of IPv6?
IPv6: Basics
- Structure of an IPv6 Address. IPv6 addresses consist of 8 blocks of 16 bits each with four-digit hexadecimal numbers. ...
- Address Assignment. ...
- Privacy Extensions. ...
- Notation Rules. ...
- URL Notation. ...
- IPv6 Address Types. ...
- IPv6 Packet Format. ...
- Stateless Address Auto-configuration. ...
- Neighbour Discovery Protocol. ...
- DHCP6. ...
How does IPv4 compare to IPv6?
- Internet Protocol version 4 (IPv4) is basically the fourth version of the Internet Protocol (IP) and was initially published in 1981. ...
- From the end-to-end connectivity perspective, IPv6 provides better results than IPv4.
- IPv4 is a 32 bit IP address, whereas IPv6 is a 128 bit IP address.
Does it support IPv6?
Today almost all popular DNS servers support IPv6. There is a requirement by an ICANN that all new TLDs must be IPv6-capable from the day they launch. From the 2017 report, it can be observed that across all TLDs, there are 11,4221,950 registered domains with AAAA records.
What is RA in IPv6?
In an IPv6 deployment, routers periodically multicast Router Advertisement (RA) messages to announce their availability and convey information to neighboring nodes that enable them to be automatically configured on the network. RA messages are used by Neighbor Discovery Protocol (NDP) to detect neighbors, advertise IPv6 prefixes, assist in address provisioning, and share link parameters such as maximum transmission unit (MTU), hop limit, advertisement intervals, and lifetime. Hosts listen for RA messages for IPv6 address autoconfiguration and discovery of link-local addresses of the neighboring routers, and can also send a Router Solicitation (RS) message to request immediate advertisements.
How does RA guard work?
RA guard works by validating RA messages on the basis of whether they meet certain criteria, configured on the switch using policies. RA guard inspects RA messages and compares the information contained in the message attributes to the configured policy. Depending on the policy, RA guard either drops or forwards the RA messages that match the conditions.
What happens when RA messages are validated?
If RA messages are validated against the configured policy, the interface moves to forwarding state.
What is the untrusted state of RA guard?
The untrusted state is the default state of an interface that is enabled for RA guard.
Can RA guard be stateless?
You can configure RA guard to operate in either stateless or stateful mode. In stateless mode, in the default state, an RA message that is received on an interface is examined and filtered on the basis of whether it matches the conditions configured in the policy attached to that interface.
What is R1 in router?
R1 is our legitimate router that will send RAs. H1 is some IPv6 host that autoconfigures itself with SLAAC, H2 is our attacker who is going to send rogue router advertisements. Let’s configure R1 so that it sends router advertisements. To do that, we need to enable unicast routing: R1 (config)#ipv6 unicast-routing.
Can we see RA from H2?
We can still see the RA from H2 because it has a lifetime of 1800 seconds. Eventually, it will timeout and disappear but until then, it will be used by H1.
What does the O flag mean in RA?
2 The next flag is O flag. O flag stands for Other configuration and it tells host receiving the RA message that he should use DHCP to get other configuration parts like DNS server IPv6 address and something else maybe. This is actually only was for now to get DNS info on the host, SLAAC in today’s implementation it’s not able to send the info to host about DNS server IPv6 address. That will probably force you to use both SLAAC and DHCPv6 to on those subsets where you want to use automatic host configuration method.
What is RFC 6101?
There is RFC 6101 that specifies how will IPv6 Router Advertisement allow IPv6 routers to give a DNS server address list to using RA router advertisement message. For now, I did not hear of this being implemented in Cisco IOS or some other router OS. One day it will be and you will be able to really chose between SLAAC and DHCPv6.
What is a router in IPv6?
In IPv6, a router is located through Router Advertisement (RA) messages sent from routers instead of by DHCP; IPv6-enabled routers that support dynamic address assignment are expected to announce themselves on the network to all clients. As such, DHCPv6 does not include any gateway information. So clients can obtain their addresses from DHCPv6 ...
What happens if you have multiple IPv6 routers?
If a high priority router becomes unavailable, clients will try a normal priority router, and finally a low priority router. Select either Low, Normal, or High from the list.
Does DHCPv6 work with RA?
This firewall will send out RA packets that advertise itself as an IPv6 router. DHCPv6 is disabled in this mode.
Does DHCPv6 support stateless address autoconfiguration?
There are a few clients that do not have support for DHCPv6. Some clients only support Stateless Address Autoconfiguration, or SLAAC for short. There is no way for the firewall to have direct knowledge of a list of hosts on the segment using SLAAC addresses, so for some environments it is much less desirable because of the lack of control and reporting of addresses. Consider address tracking and operating system support requirements when deciding how to allocate IPv6 addresses to clients on the network.
Does IPv6 work like IPv4?
Automatic address assignment for IPv6 works quite a bit differently than IPv4. Even so, most of the DHCP options are similar, but there are notable differences in behavior in how things are assigned and also how items like the gateway are handed off to clients. Unless otherwise noted, options of the same name work the same for DHCP and DHCPv6. DHCPv6 and Router Advertisements (RA) are configured under Services > DHCPv6 Server/RA. Under that page there are two tabs: One for DHCPv6 Server and one for Router Advertisements.
Does DHCPv6 include gateway information?
As such, DH CPv6 does not include any gateway information. So clients can obtain their addresses from DHCPv6 or SLAAC, but unless they are statically configured, they always locate their next hop by using RA packets sent from available gateways. To enable the RA service: Navigate to Services > DHCPv6 Server/RA.
Does Android have DHCPv6?
Some lightweight or mobile operating systems such as Android do not contain a DHCPv6 client and will only function on a local segment with IPv6 using SLAAC.
All the ICMPv6 Types and Codes
The different types and codes for the various types of messages are defined in the following table. As you can see, there are some similarities to ICMP for IPv4, so not everything is probably new to you.
Neighbor Discovery (ND) in IPv6
Now it’s time to look at the different ICMPv6 message types, starting with the Neighbor Discovery Protocol (ND or NDP).
How IPv6 Neighbor Processing works
You have learned before, that in IPv6 there is no ARP anymore. Instead there is ICMPv6 and the Solicited-Node Multicast address, but how does that all fit together? Let’s find the answers in the following chapters.
Recommended Resources for additional reading
Apart from the links throughout this course I recommend the following resources for additional information:
Book recommendations on IPv6
I can recommend the following 3 books (Amazon referral links) which I enjoyed reading:
What is IPv6 protocol?
IPv6 is an Internet Layer protocol for packet-switch ed internetworking and provides end-to-end datagram transmission across multiple IP networks, closely adhering to the design principles developed in the previous version of the protocol, Internet Protocol Version 4 (IPv4).
How does IPv6 work?
A host bringing up a new IPv6 interface first generates a unique link-local address using one of several mechanisms designed to generate a unique address. Should a non-unique address be detected, the host can try again with a newly generated address. Once a unique link-local address is established, the IPv6 host determines whether the LAN is connected on this link to any router interface that supports IPv6. It does so by sending out an ICMPv6 router solicitation message to the all-routers multicast group with its link-local address as source. If there is no answer after a predetermined number of attempts, the host concludes that no routers are connected. If it does get a response, known as a router advertisement, from a router, the response includes the network configuration information to allow establishment of a globally unique address with an appropriate unicast network prefix. There are also two flag bits that tell the host whether it should use DHCP to get further information and addresses:
What is the difference between IPv4 and IPv6?
The main advantage of IPv6 over IPv4 is its larger address space. The size of an IPv6 address is 128 bits, compared to 32 bits in IPv4. The address space therefore has 2 128 = 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (approximately 3.4 × 1038 ). Some blocks of this space and some specific addresses are reserved for special uses .
How many octets are allowed in IPv4?
IPv4 limits packets to 65,535 (2 16 −1) octets of payload. An IPv6 node can optionally handle packets over this limit, referred to as jumbograms, which can be as large as 4,294,967,295 (2 32 −1) octets. The use of jumbograms may improve performance over high- MTU links. The use of jumbograms is indicated by the Jumbo Payload Option extension header.
What is IPv6 subnet?
It simplifies processing of packets in routers by placing the responsibility for packet fragmentation into the end points. The IPv6 subnet size is standardized by fixing the size of the host identifier portion of an address to 64 bits.
How many bits are in IPv6 header?
The IPv6 packet header has a minimum size of 40 octets (320 bits). Options are implemented as extensions. This provides the opportunity to extend the protocol in the future without affecting the core packet structure. However, RFC 7872 notes that some network operators drop IPv6 packets with extension headers when they traverse transit autonomous systems .
When was IPv6 created?
The Internet Engineering Task Force adopted the IPng model on 25 July 1994, with the formation of several IPng working groups. By 1996, a series of RFCs was released defining Internet Protocol version 6 (IPv6), starting with RFC 1883. (Version 5 was used by the experimental Internet Stream Protocol .)
