WO2007028306A1

WO2007028306A1 - A method for reconstructing the network address in the ipv6 access network

Info

Publication number: WO2007028306A1
Application number: PCT/CN2006/001707
Authority: WO
Inventors: Haibo Wen; Yinglan Jiang; Qingshan Zhang; Zemin Din
Original assignee: Alcatel_Lucent
Priority date: 2005-09-09
Filing date: 2006-07-17
Publication date: 2007-03-15
Also published as: CN1929496A; CN100499669C

Abstract

A method for reconstructing the network address in the IPv6 access network includes: a) the network access equipment sends the reenable-prefix request to the route equipment; b) the route equipment forbids the network prefix which is used currently by the terminal equipment in the user network connecting with the network access equipment; c) the route equipment reassigns the network prefix to the user network connecting with the network access equipment; d) the terminal equipment in the user network reconstructs the network address according to the obtained network prefix. In the prefix shared IPv6 access network, the network access equipment could further reconstruct the address and circuit port map table, therefore, it is avoided that the normal operation of the access network is affected because of the address and circuit port map table is lost when the network access equipment is restarted for some reason or some other fault appears.

Description

Network address reconstruction method in IPv6 access network

The present invention relates to the field of communications technologies, and in particular, to a network address reconstruction method in an IPv6 access network. Background technique

With the rapid development of communication network technology and the maturity of IPv6, IPv4 access will be replaced by IPv6 access network.

In a typical IPv6 access network model as shown in Figure 1, the network access device DSLAM 12 (Digital Subscriber Line Access Multiplexer) and the CPE (Client Device) in the user networks 11A, 11B usually work in the first On the second floor, BRAS 13 (Broadband Access Server) works on the third floor. When IPv6 is introduced into this access network model, the address allocation can be allocated by the BRAS to the user network. There are multiple address configuration methods: (1) A user network has a 64-bit prefix, that is, 64 exclusive. The address space of the bit. Since the device of a user network is much smaller than 2 ⁶⁴ , the address utilization rate is not high in this way. (2) All user networks under a network access device share a 64-bit prefix, which is obviously higher than the former. The second address configuration mode can be transformed into multiple network access devices, and even a user network under one BRAS shares a 64-bit prefix.

Address assignment in IPv6 can be divided into two broad categories: stateful address assignment based on DHCPv6 (Dynamic Host Configuration Protocol) and stateless address assignment. The former can strictly control the address allocation. The latter is that the host or terminal obtains the 64-bit network prefix through the RA (Router Advertisement) message obtained from the routing device, and then attaches the Interface Identifier (interface identifier) of the host network interface that received the RA message to form a 128-bit IPv6. address. In an IPv6 network, all unicast IPv6 addresses must be successfully detected by DAD (Duplicate Address Detection) before being assigned to a network interface to ensure that the address is in the subnet (that is, the network with the same prefix). only one. From the perspective of revenue and network security, network operators do not allow direct communication between different user networks in the access network. Therefore, how to consider how multiple user networks share a prefix in the IPv6 access network model shown in Figure 1 Implement DAD detection. Generally, DAD detection can maintain an <IPv6 address, device line port, and terminal device MAC address> mapping table on the network access device (as shown in Figure 2). The address-line port mapping table completes the DAD detection in the same prefix address space. In the specific implementation, this mapping table may be changed, but as long as it can help complete the DAD function. For example: (1) When a line access device 12A of the network access device (a line port connected to the user network 11A) receives an NS (Neighbor Solicitation) message for DAD detection, the message contains the tentative provision of the request. Address, if an address already exists in the address corresponding to the address entry of a certain line port (for example, 12B) of the network access device, the address is duplicated. The network access device generates a corresponding NA (Neighbor Advertisement) message to the user network 11A, informing that the address is not available. (2) If the DAD detection finds that there is no address duplication, it waits at the time specified by IPv6. During this period, if the network access device receives an NS message for DAD detection of the same address by a line port (for example, 12B), Then, a corresponding advertisement is sent to the user networks 11A, 11B to which the two line ports 12A, 12B are connected, indicating that the address is duplicated; otherwise, the network access device adds a new address-line port corresponding to the address-line port mapping table. Mapping table entries.

There are currently a variety of memory: ROM (read-only memory), Flash (flash), RAM (random access memory), etc., in terms of price, function and access speed, network devices usually use RAM to store routing table and other data information, in the network The access device uses RAM to store the address-line port mapping table. When the access device is powered down or restarted due to some other failure, the address-line port mapping table does not exist, which will make future DAD detection impossible. The terminal device under the network access device will not work properly. Therefore, it is necessary to solve the address reconstruction method under this network model, and the network access device can further reconstruct its address-line port mapping table. Summary of the invention

An object of the present invention is to provide a method for reconfiguring a network address in an IPv6 access network, which is re-enabled based on a network prefix, and the terminal device in the user network automatically performs address reconstruction when the network access device recovers from a fault; The method includes: a), the network access device initiates a prefix re-enable request to the routing device; b), the routing device prohibits the network prefix currently used by the terminal device in the user network connected to the network access device; c), routing The device reassigns the network prefix to the user network to which the network access device is connected; d), the terminal device in the user network reconstructs the network address according to the obtained network prefix.

Preferably, the prefix re-enable request in step a) includes the network access device identification information. Preferably, the foregoing prefix re-enable request uses a router request message mode.

Preferably, in step b), the routing device constructs a router advertisement message sent to the user network under the network access device, and sets the effective lifetime of the network prefix to zero.

Preferably, the step C) routing device constructs a router advertisement message addressed to the user network under the network access device, the message including the reassigned network prefix and a suitable non-zero effective lifetime.

Preferably, the network access device is a digital subscriber line access multiplexing device, and the routing device is a broadband access server.

Based on the network address reconfiguration method in the IPv6 access network described above, the network access device receives a Neighbor Solicitation message from a terminal device of each user network, performs duplicate address detection, and reconstructs an address-line port mapping table.

A further object of the present invention is to provide a network access device address-line port mapping table reconstruction method, which enables a network access device to quickly recover an address-line port mapping table under a shared network prefix based on a multicast audience discovery protocol. . The method includes: a), a network access device constructing and issuing a multicast listener query request to a terminal device in the tenant network; _M) , the terminal device responding to the request, generating a multicast listener report; cl), network access The device reconstructs the address-line port mapping table based on the multicast audience report.

Preferably, in step al), the multicast listener query request is a regular query message requesting all terminal device network interfaces in the user network to report all the multicast groups to which they are joining.

Preferably, in step cl), the network access device obtains the network prefix through the routing device, and further records the interface identifier of the terminal device according to the multicast audience report, and further forms an address-line port mapping table.

The method of the invention effectively solves the problem of network address reconfiguration in an IPv6 access network, and causes the user network terminal to perform network address reconfiguration when the network access device needs or fails for management.

The device address-line port mapping table reconstruction method provided by the present invention can further solve the address-line port mapping caused by the network access device restarting or other failure factors for some reason under the access network model of the shared network prefix. The loss of the table in turn affects the normal operation of the access network.

DRAWINGS

Figure 1 is an IPv6 access network model; 2 is a schematic structural diagram of an address-line port mapping table in a network access device;

Figure 3 is a prefix information field format of an RA message in an IPv6 stateless address configuration;

Figure 4 is one embodiment of the present invention: the prefix is re-enabled;

Figure 5 is a prefix re-enable domain format of an RS message in an IPv6 stateless address configuration;

6 is one embodiment of the present invention: multicast audience discovery;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Embodiment 1: Prefix re-enablement (Reenable-Prefix)

This embodiment relates to RFC 2461 "IPv6 Neighbor Discovery" and RFC 2462 "IPv6 Stateless Address Auto Configuration". The network access device initiates a prefix re-enable request to the routing device, and the routing device disables the prefix used by the terminal device in the user network, and then makes the prefix a legal prefix again, so that each normally-powered terminal device in the user network is restarted. Constructing an IPv6 network address; further, the terminal device initiates DAD detection, and the network access device can successfully reconstruct the address-line port mapping table according to the message detected by the DAD.

Figure 3 shows the prefix information field format of the RA message in the IPv6 stateless address configuration. Wherein, the Type option is 3: uniquely identifies the message type; Prefix option: As described above, in the stateless address configuration, the terminal device in the user network passes the Prefix information and then attaches the terminal. The 64-bit Interface Identifier of the device interface constitutes its own IPv6 address; an IPv6 address has a Valid Lifetime option associated with it, and the effective lifetime is divided into two segments: Recommended lifetime (Preferred) Lifetime) and disapproval of usage time. During the recommended lifetime, the device can establish a new session with other devices on the network; a new session cannot be established within the time limit, but the existing session communication can still be performed.

In RFC2462, the terminal device shall perform the following processing on the prefix information field in each RA message: (1) If the Prefix option in the prefix information field does not match the network prefix of the current terminal device interface using the address, it will construct the corresponding The address is also used as a DAD test. After the DAD test succeeds, the address is assigned to the interface. (2) If the Prefix option in the prefix information field matches the prefix of the current terminal device interface address, the prefix information field is treated according to the prefix information field. The effective lifetime is determined by the remaining valid lifetime of the address, and usually does not change the remaining lifetime to the valid lifetime specified in the prefix information field. If the valid lifetime in the prefix information field is greater than 2 hours or greater than the remaining valid time to live, or the RA message is authenticated (such as by IP security or by using the mechanism defined in RFC3971).

On the network access device, an address-line port mapping table is maintained for the user network connected to its line port. When performing DAD detection, the network access device checks all address-line port mapping tables to help implement DAD detection, and does not The NS/NA messages in the user network are forwarded to other user networks, as described above.

As shown in FIG. 4, in the embodiment of the present invention, the prefix is re-enabled, and the specific process is as follows: Step S40: The network access device DSLAM needs to perform address reconfiguration, for example: for management needs or equipment Restart, etc., it informs the BRAS to re-enable the prefix. The notification process can notify the BRAS by any means, such as Simple Network Management Protocol (SNMP). Here, we use the RS (Router Request) message mode to define a new domain for the RS message, called the prefix re-enable domain. The format is shown in Figure 5: The Type option can be selected as 10, uniquely. Identifies the message type, the Length option is 1, and the Access Node # option is the number of the network access device that sent the RS message. The DSLAM constructs a new RS message carrying the prefix re-enabled domain to the BRAS.

Step S41, after obtaining the DSLAM prefix re-enabling notification message, the BRAS constructs an RA message addressed to the DSLAM. The RA message includes a prefix information field indicating the Prefix information used by the user network under the DSLAM, and the Valid Lifetime option is 0. Of course, this message needs to carry information that can authenticate this message.

Step S42: The terminal device in the user network verifies the RA message, finds that the prefix of the current used address matches the prefix information carried in the RA, and the specified Valid Lifetime is set to 0, that is, discards the currently used address.

Step S43: After the RA message is sent in step S41, the BRAS sends an RA message carrying the network prefix assigned to the user network terminal device under the network access device immediately after or after a few seconds. The Valid Lifetime and Preferred Lifetime options for this prefix are set to a reasonable non-zero value.

Step S44: The terminal device in the user network obtains the Prefix information according to the received RA message and processes the prefix information field in each RA message according to the foregoing manner to construct a new IPv6 tentative address. Further, according to the address-line port mapping table reconfiguration idea in the network access device of the present invention, in the next step S45, the terminal device interface in the user network generates an NS message for DAD detection, the NS message including new Constructed tentative address information. Step S46, the DSLAM performs DAD detection and reconstructs the address-line port mapping table according to the received related DAD information.

Embodiment 2: Multicast Listener Discovery (MLD: Multicast Listener Discovery);

This solution involves RFC2710 "IPv6 Multicast Audience Discovery" and RFC3810 "Multicast Audience Discovery (Second Edition)". This embodiment utilizes multicast queries and multicast reports in the multicast audience discovery protocol, and according to the multicast report. The IP source address reconstructs the address line port mapping table.

The IPv4 network uses the IGMP (Internet Group Management Protocol) protocol to manage the multicast membership of the local subnet. In the IPv6 network, the MLD protocol replaces the IGMP protocol. Currently, there are two versions of MLD, namely the first version of MLD and the second version of MLD. According to its relevant regulations: IPv6 routers use the MLD protocol to discover multicast members on links directly connected to them. The MLD protocol runs on the ICMP (Internet Control Message Protocol) protocol, which defines three types of message types: (1) Multicast Listener Query, which is used by the multicast router to poll the directly connected link. The situation of the members of the upper group. The query can be a regular query to query which multicast group members are on the link; or a specific group query to query if there is a member of a particular multicast group. (2) Multicast Listener Report. When the host joins the multicast group, the host interface sends this report message in response to the multicast listener query. In the first version of MLD, the IPv6 destination address of the report message and the MLD multicast address field in the report message are all set to the multicast group address that the host joins, so the report can be heard not only by the router but also on the link. Host members joining the multicast group can also hear, because of the use of delayed reporting and listening techniques, on a shared link directly connected to an interface of the router, even if there are multiple members belonging to the same multicast group , the subnet also generates only one report message. In the second version of MLD, the situation is different: The IPv6 destination address of the multicast listener report message is the multicast address that all MLD routers are listening to (FF02:0:0 _: 0 _: 0:0:0:16) The message cannot be heard by the host members of the same multicast group on the shared link. Therefore, the network interfaces belonging to the same multicast group on the same shared link will report. (3) Multicast Listener Done, when the host leaves the multicast group, its network interface sends this message.

In an IPv6 network, after a unicast address is assigned to a network interface, the network interface also joins the lowest 24 bits (XX:XXXX) of the unicast address attached to FF02:0:0:0:0:1: FF formation Solicited Multicast Group (FF02:0:0:0:0:1:FFXX:XXXX), this type of multicast group address belongs to the multicast group address that MLD needs to report multicast membership, so the network interface Will respond to the multicast listener regular query message.

As shown in FIG. 6, one embodiment of the present invention is a network access device address-line port mapping table reconstruction scheme based on a multicast audience discovery, and the specific process is: Step S60, the network access device DSLAM needs to be generated. In the case of address reconfiguration, for example: device restart, etc., it constructs a multicast listener regular query message whose destination address is the multicast address of all nodes (FF02::1).

Step S61: The terminal device in the user network receives the multicast query message, and generates a multicast audience report, where the source address of the report is the current IPv6 unicast address of the network interface.

Step S62: The DSLAM can intercept the multicast audience report by performing the MLD PROXY/SNOOPING function, record the source IP address of the report, and receive the line port of the report, and obtain the source IP address. 64-bit interface identifier. It is worth noting that the 64-bit network prefix required for address reconfiguration can be obtained by the network access device from the BRAS in any way: for example, constructing an RS message request to the BRAS to allocate network prefix information, or requesting BRAS via SNMP To obtain the network prefix information, in addition, the BRAS also periodically sends the network prefix information to the DSLAM through the RA message. The combination of the interface identifier and the network prefix constitutes the current IP address of the terminal device, and the DSLAM reconstructs the address-line port mapping table.

It is worth noting that: (1) The multicast audience report from a certain line port cannot be relayed to other user networks by the network access device; (2) This scheme is adapted to the global IPv6 address and the link-level IPv6 address. In the case of using the same network interface identifier, since the local connection address has completed DAD address detection and no duplicate address, the reconstructed routable address does not conflict.

According to the MLD version 2 standard, even if there are multiple members belonging to the same multicast group in a subnet, each multicast member sends a multicast audience report in response to the multicast query. Therefore, for an access network using MLD version 2, the network access device can reconstruct all address-line port mapping tables according to the above method.

According to the first version of the MLD standard, even if there are multiple members belonging to the same multicast group in a subnet, only one multicast member will send a multicast audience report in response to the multicast query. In a subnet of IPv6, only the IP address of the interface being used can be guaranteed to be at least 64 bits different, and the minimum is not guaranteed. The difference of 24 bits, therefore, may belong to the same solicitation multicast group by having multiple terminal device interfaces. When using the first version of MLD, the address-line port table reconstruction under this scheme may make the entry reconstruction incomplete, but it can generally be ignored in the access network, because (1), a user in the access network The multicast audience report of the network cannot be heard by devices in other user networks, so if different users have networks belonging to the same soliciting multicast group (the lower 64 bits of the addresses of these members are different), then Each user network will report a multicast audience for the multicast group; ( ₂ ) there will not be too many devices in a user network, so the lowest 24 of the addresses of multiple devices in a user network is unlikely to be the same. of.

Many other changes and modifications can be made without departing from the spirit and scope of the invention. It is to be understood that the invention is not limited to the specific embodiment, and the scope of the invention is defined by the appended claims.

Claims

Rights request

A method for reconstructing a network address in an IPv6 access network, comprising:

a), the network access device initiates a prefix re-enable request to the routing device;

b) the routing device prohibits the network prefix currently used by the terminal device in the user network connected to the network access device;

c), the routing device reassigns the network prefix to the user network to which the network access device is connected; d), the terminal device in the user network reconstructs the network address according to the obtained network prefix.

2. The network address reconfiguration method in an IPv6 access network according to claim 1, wherein in step a), the prefix re-enable request includes the network access device identification information.

The method for reconstructing a network address in an IPv6 access network according to claim 1 or 2, wherein in the step a), the prefix re-enable request uses a router request message mode.

The method for reconstructing a network address in an IPv6 access network according to claim 1, wherein in step b), the routing device constructs a router advertisement message addressed to the user network under the network access device, and sets a network thereof. The effective lifetime of the prefix is zero.

The method for reconstructing a network address in an IPv6 access network according to claim 1, wherein in the step c), the routing device constructs a router advertisement message sent to the user network under the network access device, where the message includes The reassigned network prefix and the appropriate non-zero effective lifetime.

The method for reconstructing a network address in an IPv6 access network according to any one of claims 1 to 5, wherein the network access device is a digital subscriber line access multiplexing device, and the routing device is a broadband access server. .

The method for reconstructing a network address in an IPv6 access network according to any one of claims 1 to 5, further comprising: e), the network access device receiving a neighbor request message from the terminal device in each user network, and executing Repeat address detection and reconstruct the address-line port mapping table.

8. An IPv6 network access device address-line port mapping table reconstruction method, comprising: a), a network access device constructing and issuing a multicast listener query request to a terminal device in a user network;

Bl), the terminal device responds to the request, and generates a multicast audience report; Cl), the network access device reconstructs the address-line port mapping table according to the multicast audience report.

9. The method for reconstructing an address-line port mapping table in a network access device according to claim 8, wherein in step a1, the multicast listener query request is a regular query message, and the message requests all of the user network. The terminal device network interface reports all the multicast groups it has joined.

The method for reconstructing an address-line port mapping table in a network access device according to claim 8 or 9, wherein in step cl), the network access device obtains a network prefix through the routing device, and reports according to the multicast audience. The interface identifier of the terminal device is recorded, and further forms an address-line port mapping table.