Knowledge about IPv6 Routing

Expression: the basic expression of an IPv6 address is X: X. Each number contains 4 hexadecimal data and the tool is 128 bits. The starting 0 does not need to be expressed. The above is the most basic expression method, and there are two more clear and easy-to-use methods. Some IPv6 addresses may contain a long string of 0. The standard allows "gaps" to indicate that the string is 0: 2000: 0: 0: 0: 0: 0: 0: 0: 0: 1 can be represented as: www.2cto.com 2000: 1
The two colons indicate that the address can be expanded to a complete 128-bit address. In this method, only when all the 16-bit groups are 0 will they be replaced by two colons, and the two colons can only appear once in the address. There may be a third method in the hybrid environment of IPv4 and IPv6. The minimum 32-bit IPv6 address can be used to represent an IPv4 address, which can be expressed in a hybrid manner. X: d. d. d. d. For example, IP Address: 0: 0: 0: 0: 0: 0: 10.0.0.1 is a valid IPv4 address. Combine two possible expressions. This address can also be expressed as: 10.0.0.1
Because IPv6 addresses are divided into two parts: Subnet prefixes and interface identifiers, it is expected that an IP node address can be expressed as an address carrying an additional value in a way similar to a CIDR address, it indicates the number of bits in the address as the mask. That is, the IPv6 Node Address indicates the prefix length. The length is differentiated from the IPv6 address by a slash, for example, 1030: 0: 0: 0: C9B4: FF12: 48AA: 1A2B/60 the prefix length used for routing is 60 characters. Www.2cto.com addressing mode: IPv6 has a very important statement and an important exception: in IPv6, if any node of the point-to-point link does not need to receive or send data from a non-neighbor node, they do not need a special address, that is, if the two nodes are mainly transmitting business flows, they do not need an IPv6 address. If the hardware can correctly share its network load on multiple network interfaces, multiple network interfaces can share an IPv6 address, this makes it possible to expand from the server to the Server Load balancer cluster, instead of upgrading hardware when the demand for servers increases. Www.2cto.com address type: There are three types of IPv6 addresses: unicast, multicast, and arbitrary playback. The concept of broadcast is removed. Unicast: the identifier of a single interface. Multicast: the identifier of a group of APIs. Packets sent to a wildcard IP address will be transmitted to one of the interfaces identified by this IP address (select the most recent one based on the calculation method of the routing protocol) IPv6 uses a "all nodes" multicast address to replace broadcasts that must be used in subnets. In addition, IPv6 uses broadcast addresses for original scenarios, use some more limited multicast addresses. In this way, you can add a multicast address to a node that is originally interested in the business flu carried by the broadcast, while other nodes that do not dare to raise this information can ignore packets sent to this address. Broadcast never solves the problem of information traversing the Internet, such as routing information, while multicast provides a more feasible method.
Unicast: the unicast address identifies an IPv6 interface. A node can have multiple IPv6 network interfaces. Each interface must have a unicast address. A unicast address can be considered to contain a piece of information. This information is contained in the 128 field. This address can define a specific port. In addition, the data in the address can be interpreted as multiple segments. However, when all the information is put together, it will constitute a 128-bit address that represents a node interface. The IPv6 address www.2cto.com can provide more or less information about the node's structure. This mainly depends on who observes the address and what to observe, for example, A node may only need to know that the entire 128-bit address is a globally unique identifier, rather than whether the node exists in the network. On the other hand, the router can determine the IP address. The part of the IP address identifies a unique node on a specific network or subnet. For example, an IPv6 unicast address can be regarded as a two-field. The network prefix of the network interface identifier.
The length of the interface identifier depends on the network prefix. The length of the two identifiers can be changed, depending on who interprets the interface identifier. A vro that is very close to the addressing node interface (away from the backbone network) can be used to identify the interface. Vrouters that are close to the backbone network only need a small number of positions to specify the subnet prefix. In this way, most of the vrouters are used to identify interface identifiers. Ipv6 unicast addresses include the following types: * clustered global addresses * unspecified addresses or all 0 addresses * return addresses * embedded with Ipv4 Ipv6 addresses * vendor-based and address-based vendor addresses * OSI Network Service Access Point (NSAP) address * Network Packet Exchange (IPX) address. Www.2cto.com Unicast address format: 1, interface identifier IPv6 host address interface identifier based on IEEE EUI-64 format. The modified format creates a 64-bit interface identifier based on an existing MAC address. Such an identifier is unique both locally and globally. (What is the relationship between IPv6 and MAC addresses?) 2, A globally available Unicast address can be a globally available Unicast address, including all addresses whose addresses start with 3 bits and 001 bits (this format can be used for other unicast prefixes not allocated currently ). The figure contains the following fields: FP field: Format prefix in IPv6 address, 3-bit long, used to identify which address the address belongs to in IPv6 address space. Currently, this field is "001", which indicates the globally available Unicast address. Tla id field: top-level clustering identifier, containing the highest-level address routing information. This refers to the largest routing information in the network interconnection. Currently, this field is 13 BITs, and a maximum of 8192 different top-level routes can be obtained. Www.2cto.com
RES field: this field is an 8-bit reserved field for future use and may be used to expand the top-level or lower-level clustering Identifier Field. Nla id field: ID of the next level of aggregation, 24-bit long. This identifier is used by some organizations to control top-level clustering to arrange address space. In other words, these organizations can use 24-bit fields based on their own addressing hierarchical structure. Such an entity can be divided into four internal top-level routes by two digits, and the other 22-bit address space is allocated to other entities (such as smaller local ISPs ). If these entities have enough address space, use the same method to subdivide them.
SLAID: site-level aggregation identifier, which is used by some organizations to arrange the internal network structure. Each organization can use the same IPv4 method to create its own internal hierarchical network structure. If all the 16-bit fields are used as the flat address space, a maximum of 65535 different subnets can be created. If the first eight digits are used for advanced routing within the organization, 255 advanced subnets are allowed. Each advanced subnet can have up to 255 subsubnets. Interface Identifier Field: 64-bit long, contains the 64-bit value of the IEEE EUI-64 interface identifier. It is clear that IPv6 unicast addresses can contain a large number of combinations, or even exceed the display fields that may be specified by RFC in the future, whether it is site-level clustering identifier, or the next level of clustering identifiers provide a lot of space, so that some network access suppliers and organizations can add additional topology structures by dividing the hierarchical structure and then dividing the two fields. 3. Special address and reserved address ............. 4. IPv6 addresses embedded with IPv4 addresses IPv6 provides two types of special addresses embedded with IPv4 addresses. The Higher-Order 80 bits of these two types of addresses are all 0, and the lower-Order 32 bits contain IPv4 addresses. When the middle 16 is the configured ffff, it indicates that the address is the IPv6 address of the IPv4 image. IPv4 compatible addresses are used by nodes to transmit Ipv6 packets through Ipv4 routers in a tunnel mode. These nodes understand IPv4 and IPv6.IPv4 image addresses, and are used by Ipv6 nodes to access nodes that only support Ipv4 addresses. 5 local links and local site addresses for organizations that are unwilling to apply for globally unique Ipv4 network addresses, Ipv4 network addresses are usually translated using network type 10, you can provide an option for these organizations. Outside the Organization, but the router used by the Organization should not forward these addresses. However, you cannot block the forwarding of these addresses or distinguish them from other valid IPv4 addresses. You can easily configure a vro to forward these addresses. The local link address is used to number the host on a single network link. The first 10 digits of the prefix are the local link addresses. The router does not process packets with local link addresses on the remote end and the target end, because these packets will never be forwarded. The center 54 of the package is 0. the 64-bit interface identifier is similar to the aforementioned IEEE structure. This part of the address space allows individual networks to connect up to (2 64-1) hosts. If the local link address is only used for a single network link, the local site address can be used for the site. This means that the local address can transmit data on the Intranet, but it is not allowed to directly route from the site to the global Internet. The routers in the site can only send packets inside the site, but cannot forward packets outside the site. 6. One of the goals of IPng allocation for NSAP and IPX addresses is to unify the entire online world so that IP IPx and OSI Networks can communicate with each other. To support this interoperability, IPv6 reserves 1/128 address space for both OSI and IPX. Www.2cto.com Multicast: When a node subscribes to a multicast address, it declares that it is a member of multicast. Therefore, any local router will book the multicast address with the name of the node. When other nodes on the same network want to send information to the multicast address, the IP multicast package is encapsulated into the layer multicast data. 1. The format of an IPv6 multicast address is different from that of an Ipv6 unicast address. A multicast address can only be a destination address. The first byte in the address format is all 1, marked as the multicast address.
Flag field: consists of four logos. Currently, only 4th bits are specified. This bits indicates whether the address is a well-known multicast address numbered by the Internet or a temporary multicast address used in a specific scenario. The other three digits are retained for future use. Range field: 4 digits. It is used to indicate the range of multicast. That is, the multicast group only includes nodes in the same region network, the same site, the same structure, or a node anywhere in the Ipv6 global address space. The four-digit value may be 0-15 2, and the multicast group IPv4 already has an application that uses multicast, because this application sends the same data to multiple nodes, for example, the publishing of video conferences, financial news, and stock quotations requires high bandwidth. The combination of the assigned multicast address and the multicast range can show multiple meanings and be applied to other applications. Some early-registered multicast addresses, including group router DHCP services, audio, video services, and online game services.
Consider the possible situation when the Multicast Group Identifier is "all DHCP servers. The Group ID is. 2 indicates the local range of The Link (local network link). The Ipv6 multicast address is FF02: 0: 0: 0: 0: 01: 3. The address can be interpreted: all DHCP servers in the local range, that is, DHCP servers are deployed on the same network. If the range is changed to the local site, the address means "All DHCP servers on the same site ". Pan-Play (it should be arbitrary): In a sense, multicast addresses can be shared by multiple nodes. All nodes of the multicast address members are expected to receive all packets sent to the address. A router that connects five different IP addresses to the Ethernet network, to forward a multicast copy to each network (assume that at least one multicast address is reserved on each network ). The wildcard IP address is similar to the multicast IP address. multiple nodes share one multicast IP address. The difference is that only one node is expected to receive the datagram from the wildcard IP address.
Pan-play is particularly useful for providing certain types of services, especially for services that do not require a specific relationship between the client and the server, such as domain name servers and time servers, in terms of accuracy, it is more desirable. Therefore, when a host sends a request to the Pan-play address to obtain information, the response should be the closest server associated with the Pan-play address.