IPv6

What is IPv6?

  

IPv6 (Internet Protocol Version 6) is the second generation of standard protocols for network layer protocols, also known as IPng (IP Next Generation). It provides connectionless data transmission services at the network layer where it resides. IPv6 is an upgraded version of IPv4 by IETF. It addresses many of the shortcomings of the current IPv4. The significant difference between IPv6 and IPv4 is that the IP address length has been upgraded from the original 32 bits to 128 bits. Ipv6 will be vibrant in the future competition in the marketplace with its simplified message header format, ample address space, hierarchical address structure, flexible extension header, and enhanced neighbor discovery mechanism.

  

Why IPv6?

  

IP (Internet Protocol) is the network layer protocol in the TCP/IP protocol family. The main job of the network layer protocol is to handle the transmission of IP datagrams across the network with the help of routing tables. The IPv4 protocol is the widely deployed Internet protocol today. In the early Internet development, IPv4 was rapidly developed because of its simple protocol, easy implementation, and good interoperability. However, with the rapid growth of the network and the problem of address shortage, the IETF had proposed four drafts such as IPv6, IPv7, IPv8, and IPv9, and hoped that one of these protocols could replace IPv4. After thorough discussion, the IETF finally chose IPv6 and replaced IPv4, and IPv7, IPv8, IPv9 have disappeared since then.

   

IPv6 Benefits

  

IPv6 has a 128-bit address structure that provides ample address space. It is claimed to be able to assign an IP address to every grain of sand on Earth.

 

Hierarchical aggregation improves routing efficiency. IPv6 can provide a much larger network prefix than IPv4, and the same organization can use only one prefix in its network. For ISPs, a much larger address space is available. This allows ISPs to aggregate all customers to form a single prefix and distribute it. Hierarchical aggregation results in a small number of global routing table entries and more efficient forwarding.

 

IPv6 has the ability to automatically assign IP addresses to users, enabling plug-and-play networking.

 

Higher security: IPSec is an essential part of IPv6, which realizes the high security of the IPv6 network through the AH (Authentication Header) and ESP (Encapsulating Security Payload) extension header.

 

Provides quality of service support: The new stream labeling in IPv6 allows network users to demand quality communication.

  

IPv4 vs IPv6

  

IPv4 and IPv6 are quite different in many ways. This chapter will explain the differences between IPv4 and IPv6 around address space, header formats, addressing, automatic addressing, security, QoS, and scalability.

 

Address space: the IPv4 address length of 32 bits has 2^32 assignable addresses, which is about 4.3 billion, whereas IPv6's address length is extended from IPv4's 32 bits to 128 bits with 2^128 addresses.

  

Header format: IPv6 has a more straightforward data header structure compared to IPv4, which greatly reduces the time required to process headers.

  

IPv6 address encoding adopts a hierarchical structure similar to CIDR, and its composition is similar to that of a telephone number. For example, the composition of a telephone is "country or area code + area code + telephone number", and the IPv6 address encoding is "top-level aggregation ID + secondary aggregation ID + site-level aggregation ID", both of which are composed of three different codes at different levels. Because the IPv6 network prefix can be further subdivided into multiple levels of the network, so its hierarchical addressing structure is very flexible, can effectively address aggregation, simplify routing, thereby reducing the number of routing table entries that the router must maintain and speed up the convergence of routes.

 

IPv4 route aggregation is generally based on the same IP prefixes, so compared to IPv6, there are two shortcomings of the aggregation method: first, if the IP address is not consecutive, it can not be aggregated; second, it can not be aggregated according to the multi-level as IPv6. When using IPv6 aggregation for address aggregation, an enterprise network core backbone router theoretically only needs to maintain no more than 8192 table entries, while if IPv4 aggregation is used for address aggregation, the number of table entries to be maintained by the router will be as high as tens of thousands or even more than one hundred thousand, which can be seen from the aggregation method of IPv6 significantly reduces the router's addressing and storage The IPv6 aggregation method significantly reduces the router's addressing and storage overhead.

 

Automatic Addressing, IPv6 provides two types of address configuration:

  

Dynamic Host Configuration Protocol, which inherits the IPv4 protocol, i.e., stateful address configuration configured through a DHCP server.

 

IPv6 has the unique feature of plug-and-play, and in scenarios where a DHCP server is not available, the interface address can be obtained through stateless address configuration.

 

In stateless address configuration, hosts on the same link automatically configure the interface with an IPv6 address appropriate for the link (called a link-local address) or an IPv6 address derived from a prefix advertised by the local router, using the neighbor discovery protocol.

  

The process of statelessly configuring a link-local address takes as little as one second. In contrast, an IPv4 host using DHCP would have to abandon the DHCP configuration in the event of a DHCP failure and then configure an IPv4 address on its own, a process that takes a full minute.

 

IPv6 uses built-in security mechanisms to authenticate and encrypt IP protocol packets as a way to protect defined IP protocol data traffic. Currently, IPv6 supports both AH (Authentication Header) and ESP (Encapsulated Security Payload) mechanisms.IPv6 provides both authentication and encryption services for packets at the network layer. The authentication mechanism enables the receiver to confirm the true identity of the sender and whether the data has been tampered with during transmission. Authentication enables the receiver to verify the true identity of the sender and whether the data has been tampered with during transmission. The encryption mechanism encodes the data to ensure its confidentiality; IPv4 does not provide a similar security mechanism at the network layer.

   

QoS (Quality of Service) is a technique used to address network latency and congestion. QoS in IPv4 mainly uses the Type of Service field, which defines 3 bits and 8 priorities. In IPv6, the Traffic Class field is used instead, defining a total of 4 bits and 16 priorities, and IPv6 adds an additional 20-bit Flow Label field. Intermediate forwarding devices can directly recognize different pre-defined flow labels without passing the header, and can identify the destination node according to the flow label. Currently, the application of IPv6's Flow Label is still in the experimental stage.

   

Scalability: IPv6 is highly scalable and new features can be added to the extension header that follows the IPv6 header.While the IPv4 header can only support a maximum of 60 bytes optionally, the size of the IPv6 extension header is only limited by the maximum number of bytes of the entire IPv6 packet.