IPV6 basic theory and tunnel access 2
IPV6 basic theory and tunnel access to Page 15 Connecting The IP World RFC 2373 specified in the IPv6 multicast scope value Therefore, routers need to listen to the following multicast addresses at all times maintain the flow of information on: · Node-local all nodes within the scope of multicast addresses (FF01:: 1); · Within the node-local scope all routers multicast address (FF01:: 2); · Link-local all nodes within the scope of multicast addresses (FF02:: 1); · Within the link-local scope all routers multicast address (FF02:: 2); · Site-local scope all routers multicast address within the (FF05:: 2); · Solicited-node (solicited-node) multicast address (if a router interface to join the solicited-node group); · Multicast group multicast address (if a router interface to join any multicast group). 2.4. Ipv6 in the Address Auto-configuration As everyone knows, manually configuring the host IP address is a time-consuming and tedious thing, and management assigned to the host Static IP address is a difficult task, especially when the host IP address when the need for frequent changes. In the IPv4 , The Dynamic Host Configuration Protocol (Dynamic Host ConfigurationProtocol, DHCP) enables host IP address and related configuration settings automatically. A DHCP server has an IP address pool, host from the DHCP Leased IP address and the server to obtain configuration information (such as default gateway, DNS servers, etc.), thus to achieve self Action to set the host IP address of purpose. Full-state automaton with IPv6 inherited IPv4 auto-configuration of such services, and called a full-state automaton with (stateful auto configuration). Of course, other agreements dealing with the same IP address, DHCP must be upgraded to support IPv6 Address. Obviously, it is not only carried out in support of a longer address the surface of updates, due to the addition of non-IPv6-like
State auto-configuration, for DHCPv6, the use of this new capability will be beneficial. The use of stateless auto-configuration, the node to the Less ability to automatically have a local connection, DHCP no longer to provide some other basic configuration parameters necessary to approach. The default router is not configured as part of, because by listening routers notice, any node can determine for themselves since the Has been the default router. Stateless Auto-configuration In addition to stateful autoconfiguration, IPv6 also incorporates known as stateless autoconfiguration (stateless autoconfiguration) automatic configuration service. In the course of stateless autoconfiguration, the host first through its MAC address of the NIC attached to the link-local addresses after the prefix 1,111,111,010, resulting in a link-local single point of broad IPV6 basic theory and tunnel access to Page 16 Connecting The IP World Multicast address (IEEE Ethernet MAC address has changed to 48 from 64. If the host NIC used for the 64 Bit MAC address, MAC address if the network card is still 48-bit, network card driver of a formula according to IEEE 48-bit MAC address is converted to 64-bit MAC address). And then to the address of the host to send a probe called the neighbor (neighbordiscovrey)'s request to verify address uniqueness. If the request was not heeded, then the table Ming the host of self-set link-local unicast address is unique. Otherwise, the host will use a randomly generated Interface ID to form a new link-local unicast address. Then, to the address as the source address, host to the local Link to heel all the multicast routers is called a route request (router solicitation) configuration information Request, the router with one that contains an aggregate global unicast address prefixes and other configuration information related to the routing Notice device to respond to the request. Use it to host global address from the router received the prefix their interface ID, Automatic Global home address, and then you can with the Internet in the other host communication has.
The use of stateless auto-configuration, without manual intervention will be able to change the network IP address of all hosts. For example, When an enterprise to replace a joint into the Internet, ISP, from the new ISP, get a new global address that can be aggregated before the Decorated. ISP to this address prefix from its routers upload them onto the corporate router. As the business cycle of the router will Manner to the local link to all hosts multicast Router Advertisements, a company network, all hosts will be through the Notice the address of the router receive a new prefix, after which they will automatically generate a new IP address and overwrite the old IP Address. Process see below: IPV6 basic theory and tunnel access to No. 17 Connecting The IP World Stateless Auto-configuration Neighbour Discovery Neighbour discovery is an ICMPv6 function that allows a router or host to identify other devices on its links. This information is then used in address autoconfiguration, to redirect a node to use a more appropriate router if necessary, and to maintain reachability information with its neighbours. The IPv6 Neighbour Discovery protocol is similar to a combination of the IPv4 protocols ARP, ICMP Router Discovery and ICMP Redirect. There are 5 packet types involved with neighbour discovery: _ Router solicitation, in which a host sends out a request for routers togenerate advertisements. _ Router advertisement, which allows routers to advertise their presence andother network parameters. A router will send an advertisement packet inresponse to a solicitation packet from a host. _ Neighbour solicitation, in which a node sends a packet to determine the link layer address of a neighbour or to verify that a neighbour
is still active. _ Neighbour advertisement, which is a response to a neighbour solicitation packet. These packets are also used to notify neighbours of link layer address changes. _ Redirect, which is used to inform hosts of a better first hop. These packet types are used to provide the following services: Address resolution .- This is a method for carrying out address autoconfiguration, and is achieved using the Neighbour Solicitation Message and the Neighbour Advertisement Message. Router and prefix discovery. - On connection to a link, a node needs to know the address of a router that the node can use to reach the rest of the world. The node also needs to know the prefix (or prefixes) that define the range of IP addresses on its link that it can reach without going through a router. Routers IPV6 basic theory and tunnel access to Page 18, Connecting The IP World use ICMP to convey this information to hosts, by means of router advertisements. The message may have an option attached (the source link address option), which enables the receiving node to respond directly to the router, without performing a neighbour solicitation. Immediate information. - The configuration of a router includes a defined frequency at which unsolicited advertisements are sent. If a node wants to obtain information about the nearest router immediately, rather than waiting for the next unsolicited advertisement, the node can send a router solicitation message. Each router that receives the solicitation message sends a router advertisement specifically to the node that sent the solicitation. Redirection. - If a node is aware of more than one router which it can use
to connect to wider networks, the router which it sends packets to by default will not always represent the most desirable route. ICMPv6 uses the redirect packet to communicate a more effective path to the node. Neighbour Unreachability Detection (NUD). - A node may issue solicitation requests to determine whether a path is still viable, or may listen in on acknowledgement packets of higher-layer protocols, such as TCP. If the node determines that a path is no longer viable, it attempts to establish a new link to the neighbour, or to re-establish the previous link. NUD can be used between any two devices in the network, independent of whether the devices are acting as hosts or routers. 2.5. Mobile hosts The scope of the existing Internet connection and the object has been greatly expanded, especially in the proportion of mobile hosts gradually Increase in IP protocol to the proposed new requirements. IPv4 mobile IP to provide support, typically through local agent (home agent) and remote agents (foreign agent) interaction achieved. mobile host to reach a new subnet, the Looking for remote agents, and through remote proxy location update to the local agents. Local agents resolve the land mobile host Site, the host of other packets sent to the mobile host through local agents and remote agents sent to the mobile tunnel between the main Machine. IPV6 basic theory and tunnel access to No. 19 Connecting The IP World When the mobile node to leave the field, you can follow these ways to use mobile IP (referred to as IPv4) to connect to the network Contact: (1) The foreign agent and master agent periodically send messages indicating their availability. The mobile host can also be the main Dynamic request this information. These circulars to ICMP
router circular basis for the mobile node to provide sufficient information, To enable them to make sure it is in their own field network in the field network. (2) If the mobile node is currently connected to the resident to determine their own networks, just as the same as the work of non-mobile host. (3) However, if the node to determine its own network in the field, it will receive from the foreign network "care to The site. "The address is that when the mobile host in the field network, it can reach the mobile host's temporary address. Mobile host can be To use an external mechanism (eg DHCP) to obtain in the field, effective address on the network, or it can use the mobile agent Specify an address, the address is called the foreign agent care of address (care-of address). At this point, for the Served by any mobile node in a mobile agent using the same address, and access to the network packet forwarding to the correct Nodes. (4) Once the mobile host has a network in the field addressing certain types of addresses, by sending the message, which the land Site registration to its master agent, the actual contents of packets like "If you get sent to my primary address of the package, please forward it to the This address. " (5) Thus, once the master agent to know about the package should be sent to mobile node where the forwarding, it put these packages stopped Cut down, and encapsulation, IP tunnels to mobile nodes care provided address. If the care of land The site is a configuration of the care of address by the foreign agent to receive encapsulated IP packets, unpacking, and forwarded to the mobile node; If the care of address is in the field assigned to the mobile node on the network a separate IP address of mobile node can receive With the encapsulated IP packets themselves unpacking. If the field of mobile nodes on the network to send packets, you do not need to Special operations, these hosts will continue to use their main address of packet source address of these packets need
not carry out any special Treatment. The solution in dealing with alternate routes and residential communities have difficulty moving. Circuitous route generation is due to end Host does not know the mobile host's current IP address; district hosts will have to move frequently update the registration. IPv6 for mobility provides the built-in support. First, the router in the multicast router advertisement packet, the direction of the Whether it can act as a local agent. On the same subnet to allow multiple local agents within the existence of a mobile host can arbitrarily A local registered agent. The local agency in the preservation of the inherent address of the mobile host and its care-of address (care-of address) of the comparison table, sent to the mobile host receiving packets, based on the comparison table to forward packets to the mobile owners Machine. Second, whenever the mobile host receive other host packets sent after the packet in response to the current address as the source IPV6 basic theory and tunnel access to P. 20 Connecting The IP World Address, and to move with the inherent address of the host. Other host a follow-up message to the mobile host's current address is Destination address, but only with the source routing header, header content of the inherent address of the mobile host. The use of such a mechanism The purpose is to ensure that the mobile host during the move will not be lost packet. Finally, IPv6 is defined in the redirection process. When the mobile host to switch between the cell when the mobile host re-register After the success of base stations, base station should be made to the original text of redirection package, so that the process of routing switches are biased reported Joe to re-find To the mobile host. When the other hosts to access the mobile host to go out only for the first time when the communication through the main agents, the future of communications by the mobile owners Access to its host machine and the use of temporary addresses
to communicate directly. 2.6. Ipv6 DNS IPv6 protocol has many advantages. First of all, it provides a huge address space, which in fact is to promote IPv6 The maximum power. Secondly, IPv6 address allocation structure and the address of strict hierarchy in order to facilitate address Polymerization, which greatly reduces the size of the router in the routing table. Again, IPv6 protocol support from the network node's address Dynamic configuration, can achieve plug and play functionality. Moreover, IPv6 protocol for mobile hosts have better support, for On the growing number of Internet mobile applications. In addition, IPv6 protocol security, support for multimedia streaming and other aspects Have advantages over IPv4. Application on the Internet a lot, but most can not do without Domain Name System (DNS) support, the primary role of the Domain Name System Is used for domain names and IP address translation, that is, DNS, such as web sites, Email, FTP and so on need to First conduct a DNS. IPv6 network in the DNS is very important, a number of new features and IPv6 support for DNS is not close Separable. The following from the IPv6 DNS architecture, IPv6 address resolution, IPv6 address auto-configuration and plug and play, IPv4 to IPv6 transition and other aspects of the IPv6 DNS are introduced. 2.6.1. IPv6 Domain Name System architecture IPv6 network and IPv4-DNS in the DNS architecture is the same, have adopted the domain name tree structure Space. IPv4 protocol and IPv6 protocol does not mean the need for a separate two sets of different IPv4 DNS system, and IPv6 DNS System, contrast, DNS domain name space of the system and must be consistent, that is, IPv4 and IPv6 co-owned and Manpower One of the domain name space. In the IPv4 to IPv6 transition phase, the domain name can simultaneously correspond to the number of IPv4 and IPv6, Address. IPv6 network along with the popularization of the future, IPv6 address will gradually replace IPv4 addresses. IPV6 basic theory and tunnel access to Page 21 Connecting The IP World
2.6.2. Right level of support for IPv6 addresses Can aggregate global unicast IPv6 addresses are used in the global scope address, and address must be divided into levels of poly Together. IPv6 global unicast address is assigned as follows: top-level address Aggregators TLA (that is, a large ISP or address of the tube Governing body) to obtain large address, is responsible to the sub-address Aggregators NLA (small and medium-scale ISP) to assign addresses, NLA to Site-level Address Aggregators SLA (subnet) and the network users assigned addresses. IPv6 addresses in the DNS hierarchy through Address chain technology can be a very good support. The following address resolution from the DNS forward and reverse address resolution two aspects of Analysis. a. Positive Analysis IPv4 address resource records are being resolved "A" record. IPv6 address being resolved at present, there are two funding The source records, namely, "AAAA" and "A6" records. Which, "AAAA" an earlier, it is a "A" in mind Recorded a simple extension, due to IP addresses from 32-bit extensions to the 128-bit, and expanded four times, so resource record from the "A" Expanded into four "A". "AAAA" is used to indicate the corresponding domain names and IPv6 addresses, do not support the address of the layer Second nature. "A6" set forth in RFC2874, it is to an IPv6 address with multiple "A6" record to establish contacts, Each "A6" record only contains the IPv6 addresses as part of combination assembled into a complete IPv6 address. "A6" record to support a number of "AAAA" do not have the new features, such as address aggregation, change of address (Renumber) and so on. First of all, "A6" recording under the TLA, NLA, and SLA level, the distribution of the 128-bit IPv6 address sub Solution into several levels and address of the address prefix suffix to form an address chain. Each address prefix and address of the suffix are Is the address of chain link, a complete address chain on the formation of an IPv6 address. Such ideas is compatible with IPv6 address
Hierarchy to support address aggregation. Second, the user to change the ISP, you should change with the ISP to change its own IPv6 address. If you manually modify the Subnet for all users registered in the DNS address, is a very tedious thing. While using "A6" records that Address chain, as long as the ISP to change the name of the corresponding address prefix can be, we can greatly reduce the resource records in DNS Changes. And in address allocation hierarchy Vietnam near the bottom, requires fewer changes. b. Reverse Analysis IPv6 reverse lookup records and IPv4, as is the "PTR", but the address representation in two ways. One is to use "." Separated by 16 half-byte hexadecimal number format (Nibble Format), low address in the former, high address in the post, The domain suffix is "IP6.INT.". The other is the binary string (Bit-string) format to "\", the domain suffix is "IP6.ARPA.". 16 Semi-byte hexadecimal number format and "AAAA" counterpart, is a simple extension of IPv4. Binary string format and "A6" Records of correspondence, addresses such as "A6", as can be divided into multi-level address chain, said the authority at every level with the "DNAME" Records. And "A6", as a binary string format also supports address-level features. In short, to address chain, expressed in the form of IPv6 address reflects the address of the hierarchy, support address aggregation and address more Change. However, due to a full address resolution into multiple steps, need to follow the address allocation hierarchy To a different DNS server to query. All inquiries are successfully resolved to get the full results. This is bound to be To extend the analysis time, the chance of error has also increased. Therefore, the need to further improve the DNS address of chain functions and improving the domain name The speed of analysis in order to provide users with satisfactory service. 2.6.3. IPv6 Plug and Play with the DNS IPv6 protocol support Address Auto-configuration, which is a plug and play mechanism, without any human intervention the situation
Under the conditions, IPv6 network interfaces available to link local address, site local addresses and global addresses, and can prevent Only address to repeat. IPv6 supports stateless address autoconfiguration and stateful address autoconfiguration in two ways. IPv6 nodes through the address auto-configuration of IPv6 addresses and gateway address. However, the address auto-configuration does not Including the DNS servers automatically configured. How to automatically discover the DNS server to provide resolution services is also a need for solution The outstanding issues. Under study DNS server auto-discovery solution that can be divided into two types of non-state and the state. Stateless mode In the stateless mode, you need to subnet the internal DNS server is configured to site-wide anycast address. To To automatically configure the nodes to the anycast address to send the server address for the purpose of discovery requests, ask DNS server to Sites, domain names and search paths and other DNS information. The request to reach the nearest DNS server, server, according to requests Demand, the answer unicast DNS server addresses, domain names and search paths and other DNS information. Nodes in the server's response in accordance with Purchase local DNS information, future DNS requests directly with the unicast address to send to the DNS server. Alternatively, you can not site-wide anycast address, while the use of site-wide multicast address or a multi-link Multicast address. Also has been using the site within the scope of the anycast address as the DNS server addresses, all of the DNS solution Analysis of the request is sent to the anycast address. To the nearest DNS server is responsible for parsing the request, to be resolved knot Fruit, after the results returned request node, rather than the practice of the unicast DNS server addresses, domain names and search paths And other DNS information to tell the node. From the network scalability, security, usability and other aspects into account, the first use of
Site within the anycast address as the DNS server address ways relatively good.