Hey, guys!
Glad to share knowledge on the forum.
Do you know the Highlights of IPv6?
1. A 128-bit address structure, providing sufficient address space
A major advantage of IPv6 is the almost infinite IP address space. IPv6 increases the size of an IP address from 32 bits to 128 bits, which is four times of that of IPv4. A 128-bit address structure is able to provide about 4,300,000,0004 addresses, meeting almost any address assignment requirements that can be predicted. (Theoretically, 4,300,000,000 IPv4 addresses can be provided; however, 4,300,000,0004IPv6 addresses can be provided.)
2. Layered address structure
The layered address structure realizes rapid route lookup, reduces the size of IPv6 routing tables with the aid of route aggregation, and thereby improves the forwarding efficiency of routers.
3. Address autoconfiguration
IPv6 enables hosts to discover networks and obtain IPv6 addresses using address autoconfiguration, which greatly improves the network manageability. Using address autoconfiguration, user devices (such as mobile phones and wireless devices) support plug-and-play, without requiring manual configuration or using a private server (such as a DHCP server). IPv6 supports stateful address autoconfiguration and stateless address autoconfiguration.
a. In stateful address autoconfiguration, the host obtains the address and other configuration information from the server.
b. In stateless address autoconfiguration, the host automatically configures address information that contains the prefix and interface ID of the host as reported by the local router. If there is no router on the link, the host can automatically configure only a link-local address for interoperating with the local node.
4. Source/Destination address selection
To specify or plan source/destination addresses of the packets sent by the system, the network administrator can define a set of address selection rules. These rules form an address selection policy table. The policy table is similar to a routing table and employs the longest matching rule for prefix lookup. The address selection result is determined together by the source address and destination address.
A source address is selected according to the following rules. Among the rules below, the rule with a smaller number has a higher priority. A candidate address is preferred if it:
1) Is the same as the destination address.
2) Has an appropriate effective scope.
3) Is not a deprecated address.
4) Is a home address.
5) Is the address of an outgoing interface.
6) Has the same label value as the destination address.
7) Has the longest matching prefix.
The candidate address can be a unicast address that is configured on the specified outgoing interface. If a source address that has the same label value as and is in the same address range with the destination address is not found on the outgoing interface, such a source address can be selected on another interface.
A destination address is selected according to the following rules. Among the rules below, the rule with a smaller number has a higher priority. A candidate address is preferred if it:
1) Is not an unusable address.
2) Has an appropriate effective scope.
3) Is not a deprecated address.
4) Is a home address.
5) Has the same label value as the source address.
6) Has a larger precedence value.
7) Prefer native transport (6over4 or 6to4 tunnel is not required).
8) Has a smaller effective scope.
9) Has the longest matching prefix.
10) Otherwise, leave the order unchanged.
5. Support for QoS
New fields are added in the IPv6 header to define how to label and process flows. Flows are identified by the Flow Label field in the header. The Flow Label field allows routers to identify the packets of a certain flow and provide special processing for these packets.
6. Flexible and simple extension headers
Compared with an IPv4 header, an IPv6 header deletes the IHL, Identification, Flags, Fragment Offset, Header Checksum, Options, and Padding fields, and adds the Flow Label field, which helps improve the header processing efficiency. In addition, to better support different options, IPv6 introduces multiple extension headers. With these extension headers, it is unnecessary to modify the existing packet structure when new options are added, which greatly improves the flexibility of IPv6.
Thanks!
