IPv6 QoS and its implementation (1)

At present, IPv4 QoS has been well developed. Therefore, before large-scale IPv6 deployment, we can use IPv4 QoS to further study the use of the Flow Label mechanism. From the current situation, we can use Diff-Serv to implement QoS. With the development of technology and standard maturity, we can gradually introduce other more effective methods. The final goal is to solve IPv6 QoS with the maturity of QoS Architecture and implementation method of ITU-T.
The current information network can be summarized by "Everything over IP" and "IP over Everything. The industry has basically reached a consensus that IP networks will become the infrastructure for the next generation of information networks. However, free, open, and "Best Effort" IP networks require a lot of improvements when taking on such responsibilities.
On the one hand, due to the rapid development of broadband networks, the large-scale deployment of NGN (Next Generation Network), 3G networks, and home networks will soon become a reality, requiring a large number of IP addresses, however, IPv4 addresses, which are widely used at present, will be exhausted in the near future due to the shortage of the total quantity and unfair allocation. Therefore, as early as 10 years ago, due to the high-speed growth of Class B address demand, it was just a few days to see the address depletion, which once caused a panic and developed the IPv6 technology with a huge address space. At the same time, it has also developed CIDR (classless Inter-Domain Routing) and reserved address/NAT technology to further delay the consumption of IPv4 addresses. On the other hand, IPv4 cannot meet the development requirements of the Next Generation Network in terms of automatic Address Configuration, QoS, security, and mobility. Therefore, IPv6 not only solves the address problem, improvements have also been made in other aspects.

I wanted IPv6 to solve a series of problems once and for all, but after more than 10 years of development, many goals have not been achieved, including the IPv6 QoS questions to be discussed below.

IPv6 QoS Basic Information

Compared with IPv4, IPv6 provides more QoS measures to improve or even completely solve the network quality of service. The initial idea was to introduce the Flow Label mechanism to help process QoS based on the research progress of IP QoS at that time. Due to the limitations of the development level of network technology at that time, the first mature result was launched around 1994, namely the so-called Int-Serv model. Before information transmission, this model uses the Resource Reservation Protocol (RSVP) to establish a channel that can ensure QoS-related indicators. This idea seems to be feasible, because the similar ATM technology has achieved great success in QoS, or one of the main features of the latter is to solve the QoS problem (of course, related Technologies are still evolving ). However, Int-Serv is not widely used. Today, we will analyze the reasons. We can find that the number of circuits/streams supported by the ATM network is basically extended in units of thousands (thousands), while the IP network, in a global network such as the Internet, its business flow is basically the basic unit of millions (millions), which is difficult for router devices in the network to support such a large number of soft states. At the same time, there are also issues such as cross-carrier Resource Reservation Management. Later, the Diff-Serv model was further developed. It simplifies the classification of network services, solves the scalability problem, and provides a feasible solution for QoS of IP networks. However, the Diff-Serv model does not provide an end-to-end solution. The implementation of IP QoS must be achieved through), network Traffic planning or Traffic Engineering (Traffic Engineering, TE) and other measures jointly provided.

IPv6 QoS Definition

The implementation of IP QoS requires the full support of all relevant elements in the network, including applications, terminals and network devices. At the basic IP protocol level, some fields are defined to support QoS implementation. The same is true for IPv6.

IPv6 Header Format

The IPv6 Header Format 1 is shown in the figure (the IPv4 Header Format is also shown in the figure for comparison ). Compared with IPv4, IPv6 adopts a more regular structure to facilitate high-speed processing using hardware. IPv6 defines a fixed-length basic header. Other options are classified as Extended Headers, including Hop by Hop headers that must be processed by each network node.

It can be seen that IPv6 has two fields related to QoS, namely the Traffic Class and TC fields and the Flow Label and FL fields. The traffic type field has eight bits, which have the same function as the IPv4 service type (ToS) field and is used to identify the Service category of the message. The Flow Label field has 20 bits, identifies a package that belongs to the same business flow. A stream tag uniquely identifies a business flow along with the source and target addresses. All packages in the same stream have the same stream tag, so that the stream with the same QoS requirements can be processed quickly and the same.