ccna certification history

ccna certification history.The implementation of IPv6 is an inevitable trend. IPv6 makes a number of improvements to IPv4 and its key features are described below.The 128-bit address scheme (3.4X1038 addresses) provides a sufficiently large address space, and the sufficient address space will greatly meet the growing demand for IP addresses from networked smart devices such as personal digital assistants, mobile phones, home network access devices, smart gaming terminals, security surveillance devices and IPTV.The multi-level addressing hierarchy facilitates route aggregation, improving routing efficiency and scalability. Network AddressTranslation (NAT) is not required, making end-to-end communication easier. IPv6 address autoconfiguration supports plug-and-play, making it possible to deploy new devices on the Internet at scale.IPv6 supports both stateful and stateless address auto-configuration methods. There is no broadcast address in IPv6, its function is replaced by multicast address, and ARP broadcast is replaced by local link multicast. IPv6 simplifies packet headers by eliminating the need to process checksums, thus reducing processor overhead and saving networkbandwidth, helping to improve network device performance and forwarding efficiency. The flow label field in IPv6 allows traffic differentiation without looking at transport layer information, which provides more reliable QoS guarantees.The IPv6 protocol has built-in security and mobility. Mobility allows devices to move around the network without disrupting network connectivity. IPv6 includes IPSec as standard, enabling end-to-end secure communications with all endpoints secured.The concept of extended packet headers was introduced in IPv6 to replace the variable length option present in IPv4 packet headers with extended packet headers, further improving routing performance and efficiency.2.2.2 IPv6 Addresses and IPv6 Basic Packet Header FormatIPv4 addresses are represented in dotted decimal format, while IPv6 uses a colon divided hexadecimal format. IPv6 consists of two parts: the network prefix and the interface ID. IPv6 uses the IPv6 address/prefix length format to represent the network portion of an IPv6 address, with a prefix length range of 0.128. A typical IPv6 prefix length of /64oIPv6 address structure is shown in Figure 2.7.Network Prefix Interface ID 2018:00D3:0000:0000:02BB:00FF:0000:2019/64