IPv6 tutorial – Part 8: Special addresses
The special IPv6 addresses discussed in this part of the IPv6 tutorial are the unspecified address, the loopback address, IPv4-mapped addresses, 6to4 addresses, multicast addresses, and the solicited-node address.
Last time, I talked about zone IDs and unique local IPv6 unicast addresses.
Today, I will introduce some special addresses.
In practice, usually only the networking guys really have to deal with these addresses.
But as a Windows admin, you should have at least heard of the terms.
The IPv6 unspecified address is specified as “0:0:0:0:0:0:0:0” (or “::” if you have a sense for mathematical beauty).
I think, this naming convention is somewhat funny.It reminds me of the “unspeakable word.”
But there is also some sense in this because applications use the unspecified address as a variable for, well, an unspecified address.
I guess, you won’t see this address often, just like you didn’t have many encounters with the unspecified IPv4 address 0.0.0.0.
Note that you can’t assign this address to an interface, which also makes sense because then you would specify it, which is strictly forbidden.
Like the loopback address, IPv4-mapped addresses are only used for internal representation on a host.
They allow developers to use one API for both IPv4 and IPv6 calls.
The syntax of IPv4-mapped addresses looks like this: :FFFF:w.x.y.z, where “w.x.y.z” is the IPv4 address that is represented in the IPv6 address.
6to4 is a tunneling technique that allows two IPv6 cable systems to communicate over an IPv4 network (usually the Internet).
For this, at least one of the IPv6 systems needs an IPv4 address and a special IPv6 address, the so-called 6to4 address.
A computer that has a 6to4 address is called “6to4 host.” This transition technology will mostly likely be used by computers in IPv4 networks to reach IPv6-only hosts.
Essentially, the 6to4 address makes the 6to4 host appear on the “IPv6 landscape” even if it is not directly reachable through IPv6 by encapsulating IPv6 packets in IPv4 packets.
The IPv4 packets are converted to IPv6 packets and vice versa by a 6to4 gateway.
6to4 addresses have the prefix 2002::/16. The next 32 bits are the IPv4 address of the 6to4 host converted into hex.
Since a 6to4 address can only be created by using a unique public IPv4 address, the corresponding IPv6 address is also unique. The last 80 bits are for the local network and the host.
IPv6 multicast addresses
Like in IPv4, IPv6 multicast addresses are used to send the same data to multiple hosts simultaneously.
Since multicast-capable software, such as OS imaging tools, typically do all the IP configuration, Windows admins usually are not bothered with the networking details.
But if you ever stumble across an IPv6 address that begins with FF, you know what you are dealing with.
A special type of multicast address are the solicited-node addresses, which have the prefix FF02::1:FF00:0/104.
Solicited-node addresses are used for neighbor discovery, which I already discussed in my article about the new IPv6 features.
If a host needs to know the MAC address that belongs to a certain IP address, it won’t use an ARP broadcast like in IPv4.
Instead, it would use multicast to contact only those hosts that listen to the solicited-node addresses where the last 24 bits are identical to the ones in the IP address that has to be resolved.
- IPv6 tutorial – Part 6: Site-local addresses and link-local addresses
https://4sysops.com/archives/ipv6-tutorial-part-6-site-local-addresses-and-link-local-addresses/ In ...
- IPv6 tutorial – Part 7: Zone ID and unique local IPv6 unicast addresses
The zone ID is used to distinguish ambiguous link-local and site-local addresses. Unique local IPv6 ...
- IPv6 tutorial – Part 5: Address types and global unicast addresses
https://4sysops.com/archives/ipv6-tutorial-part-5-address-types-and-global-unicast-addresses/ In my ...
- IPv6 tutorial 4 IPv6 address syntax
https://4sysops.com/archives/ipv6-tutorial-part-4-ipv6-address-syntax/ Now that you know about the n ...
- IPv6 tutorial 3 New features: IPsec and LAN features
https://4sysops.com/archives/ipv6-tutorial-part-3-new-features-ipsec-and-lan-features/ In the last p ...
- IPv6 tutorial 2 New features: Routing
https://4sysops.com/archives/ipv6-part-2-new-features-routing/ Routing路由选择 In the last post of my IP ...
- IPv6 tutorial 1 Get started now
https://4sysops.com/archives/ipv6-part-1-get-started-now/ You’ve probably heard the news that the In ...
- docker 支持ipv6 (核心要点是ndp需要把docker内的ip全部加入到ndplist中来)
IPv6 with Docker Estimated reading time: 10 minutes The information in this section explains IPv6 wi ...
- [LeetCode] Validate IP Address 验证IP地址
In this problem, your job to write a function to check whether a input string is a valid IPv4 addres ...
背景: go语言处理db.json的时候,具体代码的变量定义和db字段.json输出的时候可能不一样. 这个时候,我们需要用tag的方式来进行定义. 例如: type MyStruct struct ...
为了方便应用程序的访问FastDFS,官网提供了fastdfs-client-java,以便更好的与应用程序结合使用. 下载fastdfs-client-java源码添加到项目工程里面,添加配置文件: ...
- Effective java-枚举和注解思维导图
- Web应用的组件化（二）——管控平台 #7
Web应用的组件化(二) 管控平台 在上一篇中我们提到了组件化的大致思路,这一篇主要讲述在这么做之后,我们需要哪些外围手段去管控整个开发过程.从各种角度看,面对较大规模前端开发团队,都有必要建立这么一 ...
Beta冲刺序列: Beta凡事预则立 :Beta No.0 Beta冲刺Day1:Beta No.1 Beta冲刺Day2:Beta No.2 Beta冲刺Day3:Beta No.3 Beta冲刺 ...
第三章:TensorFlow入门 TensorFlow存在计算模型,数据模型和运算模型(本文用TF代表TensorFlow) 3.1 计算模型-计算图 3.1.1 计算图的概念 TensorFlow这 ...
个容器副本,使用nginx:1.13.0镜像.假设使用一段时期以后,nginx的版本升级到1.13.1了,如何将该服务的镜像版本升级到新的版本?实验步骤及截图如下: 步骤截图: 个容器,选择镜像ngi ...
python导出安装包及版本 pip freeze > requirements.txt 批量安装pip install -r requirements.txt