Understanding link local address and site local address

Understanding the link local address and site local address involves a concept when learning IPV6. link-local address is called "link local address" in Chinese. Its prefix is FE80 :: /64 example of a link-local address: FE80: 713e: a426: d167: 37ab. In fact, this concept is similar to that in ipv4, if an address such as 169.254.XXX.XXX is automatically generated when DHCP allocation fails, the router should not forward the packet containing the link-local address in the source or destination address. Such packets can only be interconnected in one LAN. <IPV6 address types> can be divided into three categories: 1. Unicast address 2. multicast address 3. Any multicast address Unicast -- Unicast: one to one Unicast Address is used for one-to-one connection. IPv6 Unicast addresses can be 1-Aggregate Global Unicast Address 2xxx: xxxxx/3-3FFF :: FFFF 2001:/16 IPV6 Internet Address 2002:/16 6to4 transition Address 2-Link Local Address FE80:/10 (the first 10 digits start with FE80) 3-Site Local Address (Private) FEC0:/10 4-Unspecified Address 0: 0: 0: 0: 0: 0: 0: 0/128 => :: /128 5-Loopback Address 0: 0: 0: 0: 0: 0: 0: 1/128 = >:: 1/128 6-IPv4 Compatible Ddress: 192.168.30.1 = >:c0a8: 1E01 the following are some specific descriptions of unicast addresses: 1. Public IP addresses that can be routed globally are assigned by IANA by Aggregate global unicast address: 2000 :: /3 occupies 12.5% IPV6 address space: 2000: 0000: 0000: 0000: 0000: 0000: 0000: 0000--3FFF: FFFF: the FFFF prefix contains a total of 8192/16 prefixes currently used for IPV6 Internet operation: 2001:/162002 :: /16 retains the 3ffe:/16 prefix for the node that uses the 6-TO-4 transition mechanism. 2. Local link address: link-local address when IPV6 is enabled on a node, each interface at the start time automatically generates a link-local The 64-bit prefix of ddress is specified by the standard, and the last 64-bit is constructed according to the EUI-64 format. Note: On this Link, the next hop in the routing table is the Link Local address of the peer, it is not a public IP address Prefix: FE80:/10 range: it can only be used on a local link. It cannot be used for routes between subnets. Why do we need link-local? Many IPv6 addresses can be configured on one interface, therefore, you may have many next hops when learning routing. The Link Local address uniquely identifies a node. The Local Link shows that the next hop is the Local Link address of the Peer Link. The Link Local address of the node and Router does not change during network re-addressing, so it is easy to make a change without worrying about network accessibility. R1 (config-if) # ipv6 address FE80: 0: 0: 0: 0123: 0456: 0789: 0abc link-local manually specify link-local address 3. local site address: the private IP address of site-local addressIPV6 occupies only 0.1% Prefix: FEC0 :: /10 and the last 54 BITs are used for subnet IDs. The last 64 bits are used for the host ID range. They can only be used at the site and cannot be used on the Internet. For example: allocate 10 subnets locally. 1. FEC0: 0: 0: 0001:/642, FEC0: 0: 0: 0002:/643, and FEC0: 0: 0: 0003: :/6410, FEC0: 0: 0: 000A:/64 the local site address is designed for devices that will never communicate with the Global IPV6 Internet. For example: printer, Intranet server, network switch, etc. 4. Unspecified address format: 0: 0: 0: 0: 0: 0: 0: 0 indicates that the address is not specified, or all the routes in the table are written in the default routing era. 5. Loopack address format: 0: 0: 0: 0: 0: 0: 0: 1 is the same as the 127.0.0.1 address in IPV4, it indicates the IPV6 Address of node 6 and embedded IPV4 Address IPv4 Compatible Address 1 and IPV4 Compatible IPV6 Address. It is used to establish an automatic tunnel on the IPV4 network to transmit IPV6 packets. The 96-bit high is set to 0, and the IPV4 address 0000: 0000: 0000: 0000: 0000: 0000: 206.123.31.2 0000: 0000: 0000: 0000: 0000: 0000: ce7b: 1f01 because of this mechanism is not very good, it is no longer used, instead, we adopt a better transition mechanism. 2. ing IPV4 IPV6 addresses. It is only used for local regions with IPV4 and IPV6 Dual-protocol stack nodes, where 80-bit high is set to 0, and then 16-bit is set to 1, and IPV4 address 0000: 0000: 0000: 0000: 0000: ffff: 206.123.31.2 0000: 0000: 0000: 0000: 0000: ffff: ce7b: 1f01EUI-64 format: Extended unique identifier in IPV6, stateless automatic configuration mechanism uses EUI-64 format to automatically configure IPV6 addresses the so-called stateless automatic configuration is a mechanism that allows nodes to configure their own IPV6 addresses without DHCP servers in the network. EUI-64 construction rules-according to the MAC address of the interface plus a fixed prefix to generate an IPV6 address Working principle: automatically extend the 48-bit Ethernet MAC address to 64bit, after a 64bit prefix, create an IPV6 address. Separate the 48-bit MAC address from the middle and insert a fixed value FFFE 0050: 3EE4: 4C00 --> 0050: 3EFF: FEE4: 4C00 II. 7th bits are reversed. If it is 0, it is changed to 1. If it is 1, it will be changed to 0 0050: 3EFF: FEE4: 4C00 --> 0250: 3EFF: FEE4: 4C00 3. Add the prefix -- FE80: 0250: 3EFF: FEE4: 4C00. This is the reason for the complete IPV6 address reversal: In the MAC address, 7th bits for 1 indicates local management, 0 indicates global management in EUI-64 format, 7th bits for 1 indicates globally unique, 0 indicates that the local unique Multicast address Multicast is not broadcast in IPV6. Instead of the prefix FF00 :: /8 occupies 0.38% of the IPV6 address space. 1111 1111 4bit 4bit | → fixed value | → flag | → range | flag 0000 indicates a permanent multicast address, the 0001 flag assigned to various technologies indicates that the CIDR block that can be used by users defines the CIDR block. The definition of the CIDR block is as follows: binary hexadecimal range type 0001 1 Local interface range 0010 2 Local Link range 0011 3 local subnet range 0100 4 local management range 0101 5 local site range private network address similar to multicast 1000 8 organization scope: 1110 E the public IP addresses of multicast-like Global IP addresses are as follows: FF02: 1 all nodes in the local link range FF02: 2 all routers in the local link range FF02: 5 all ospf routersFF02 :: 9 all rip routers all routers running RIP FF02: A al L all vrouters that run the command :: 2. the multicast address solicited-node multicast address of all routers within the scope of a site is the important East-East Special multicast address, each Unicast address and any multicast address configured on the node or router interface will automatically generate a corresponding multicast address for the requested node. Note that link-local address also generates a multicast address for the requested node. Scope of Work: only valid features on the local link: 1. on the local link, the multicast address group of the requested node usually contains only one user. 2. If you know the IPV6 address of a node, you can calculate the multicast address of the requested node: 1. There is no arp in IPV6. ICMP replaces the ARP function. The multicast address of the requested node is used by the node to obtain the link layer address of the neighbor node on the same local link. 2. It is used to detect duplicate addresses. DAD, before you use stateless automatic configuration to configure an IPV6 address as your own, the node uses DAD to verify whether the address has been used on its local link. Prefix: FF02: 0000: 0000: 0000: 0000: 0001: FFxx: xxxx/104 FF02: 1: FFxx: xxxx/104 how to generate: the first 104 bits of the multicast address of the requested node are fixed. You can move the last 24 bits of the IP address to the end, for example, IPv6 --- 2001: 1234: 5678/64 requested node multicast address --- FF02: 1: FF34: 5678/104 where FF02: 1: FF is a fixed part. A total of 104-bit multicast IP addresses are mapped to MAC addresses: ing rules: the first 16 bits of the multicast MAC address are fixed to 0x3333. You can map the last 32 bits of the multicast IPV6 address to the last 32 bits of the multicast MAC address. For example, if the IPV6 address is -- FF12: 1234: 5678/64, the corresponding multicast MAC address is -- 3333: 1234: 5678 0x3333. For example, the multicast address of all nodes: FF02:: 0001 the corresponding multicast MAC address: 3333: 0000: 0001 any multicast address Anycast address is applied in one-to-nearest (one to nearly) A single address is shared by multiple devices. assign an IPv6 unicast address to devices with the same function. the sender sends a packet with an arbitrary stream as the target address. When the router receives the packet, it forwards the packet to the device closest to the IP address. the Unicast address is used to allocate any multicast address. unicast addresses are addresses that are not equipped with any unicast addresses. However, when a unicast address is assigned to more than one interface, the unicast address becomes an arbitrary Unicast address. For example, for Mobile, Mobile devices roam to other regions without accessing the original access point. You only need to find the nearest one. Required IPV6 address: Once IPV6 is enabled on the node, the interface will automatically generate the following addresses: 1. Local link address 2. loopback address 3. multicast address FF02 on all nodes :: 14. For a vro, there will also be FF02: 25. The multicast address of the requested node. If the interface is configured with an IPV6 unicast address, the multicast address of the requested node, "How to Write MAP in Frame Relay", will also be generated. Note: two maps must be written, one of which is the MAP of the configured IPV6 address, one MAP is the link-local address. Otherwise, the PING will fail because there is no MAP ing. <IPV6 basic command> R1 (config) # ipv6 unicast-routing enable IPV6 routing on the router R1 (config-if) # ipv6 enable IPV6 under the interface, A link-local address R1 (config-if) # ipv6 address 2001: 1/64 is automatically generated to specify an IP address, after configuration, a link-local address R1 (config-if) # ipv6 address FE80: 0: 0: 0: 0123: 0456: 0789: 0abc link-local manually specify the link-local address R1 (config-if) # ipv6 address 2001: 0410: 0: 1 :: /64 eui-64 uses eui-64 format to automatically generate low 64-bit R1 (config-if) for IPV6 addresses # ipv6 unnumbered allows this interface to generate source address R1 (config-if) using the MAC address of another interface) # ipv6 mtu 1500 configuration interface MTU value R1 (config-if) # ipv6 nd suppress-ra disable automatic delivery of prefix R2 (config-rtr) # no split-horizon disable horizontal split note that the horizontal split of IPV6 is disabled under the process, not the show ipv6 interface e0 under the interface to display IPV6 interface information, including IPV6 address