CN107959627B

CN107959627B - Address transmission method and network equipment

Info

Publication number: CN107959627B
Application number: CN201610900284.9A
Authority: CN
Inventors: 张华�; 叶鑫; 任庆丰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-10-14
Filing date: 2016-10-14
Publication date: 2021-02-12
Anticipated expiration: 2036-10-14
Also published as: CN113037631B; CN113037631A; CN107959627A

Abstract

The application provides an address transmission method and network equipment. In an address delivery method, a first network device obtains a first set of reachable IP address entries from a first link state database. Each reachable IP address entry in the first set of reachable IP address entries includes a reachable IP address and a set of region identifications. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region. The first network device adds the identifier of the first area in the area identifier set of each reachable IP address entry in the first set of reachable IP address entries, and adds the identifier to a second link state database. By the scheme provided by the application, the condition that the introduced reachable IP address entry is introduced back to the already-arrived area is avoided, and the problem that a loop appears when routing is introduced between the areas is conveniently solved.

Description

Address transmission method and network equipment

Technical Field

The present invention relates to the field of communications technologies, and in particular, to an address transmission method and a network device.

Background

The Intermediate System to Intermediate System (IS-IS) routing protocol IS an interior gateway protocol. In the IS-IS routing protocol, in order to accelerate the routing convergence speed and reduce the processing pressure of equipment, the network IS divided into areas.

In transregional message forwarding, if there are multiple egress devices to an external region, the network device needs to know the routing information outside the region. Therefore, one of a plurality of exit devices can be used in message forwarding, and the total network overhead is minimized. Inter-area route introduction is a way to know the routes of the network devices outside the area. Area border network devices, which are located in multiple areas at the same time, may introduce a route in one area into another area, and the introduced route may be transmitted to a network device in the other area. The introduction of inter-domain routing can be realized by introducing inter-domain reachable Internet Protocol (IP) address entries. When routing entries between regions, an reachable IP address entry from a region may be introduced back into the region. When the network structure changes in the one area, the incoming reachable IP address entry may cause a loop to occur.

Disclosure of Invention

The application provides an address transmission method and network equipment, which are beneficial to simply solving the problem that a loop appears when routing is introduced between areas.

In a first aspect, an address delivery method is provided. Wherein the first network device is located in a first area and a second area. The first network device includes a first link state database and a second link state database. The first link state database stores link state data for network devices in the first area. The second link state database stores link state data of network devices in the second area. The method comprises the following steps:

the first network device obtains a first set of reachable internet protocol, IP, address entries from the first link state database. Each reachable IP address entry in the first set of reachable IP address entries includes a reachable IP address and a set of area identifications. The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region.

The first network device generates a second reachable IP address entry set according to the first reachable IP address entry set, adds the second reachable IP address entry set to the link state data of the first network device in the second link state database, and the generating includes adding the identifier of the first area to an area identifier set of each reachable IP address entry in the first reachable IP address entry set.

The first network device sends a link state message to a second network device in the second region, where the link state message includes link state data of the first network device in the second link state database to which the second reachable IP address entry set is added.

In the above scheme, when a reachable IP address entry is introduced from a first area to a second area, the identifier of the first area is increased. By adding the area identification set in the reachable IP address entry, the area passed by the reachable IP address entry can be identified in route introduction. Therefore, the method avoids leading the led-out reachable IP address entry back to the region which has already been reached, and reduces the possibility of loop when the network structure in the region is changed. The scheme does not need to be customized according to different networks, and different control strategies do not need to be configured on each network device which is introduced by execution, so that the possibility of wrong configuration is reduced. Under the condition that the network area division is complex, the method is beneficial to simply solving the problem that the loop is introduced by the inter-area route.

Optionally, the generating further comprises deleting reachable IP address entries of the set of area identities that include the identity of the first area from the first set of reachable IP address entries before adding the identity of the first area. In the case of an interface misconfiguration, reachable IP address entries that are dropped out within the first area are transmitted back to the network devices of the first area in a link state synchronized manner. However, the first network device does not re-introduce the reachable IP address entry including the identifier of the first area, and further, the reachable IP address entry including the identifier of the first area is not re-introduced, which helps to avoid a loop occurring when the network structure in the area changes.

Optionally, the method further comprises: and when the first network equipment generates a routing table of the first network equipment according to the first link state database and the second link state database, excluding a reachable IP address entry of which the area identification set comprises the identification of the first area. In the case of an interface misconfiguration, reachable IP address entries that are dropped out within the first area are transmitted back to the network devices of the first area in a link state synchronized manner. And when the first network equipment calculates the local route, eliminating reachable IP address entries including the own region identification in the region, namely eliminating reachable IP address entries led out by the own region, which is helpful for avoiding the occurrence of loops when the network structure in the region changes.

Optionally, the method further comprises: the first network device generates a routing table for the first network device using reachable IP address entries in the first link state database and the second link state database that lack a set of area identifications. In a specific scenario, for example, when a Label Distribution Protocol (LDP) and an IS-IS Protocol are synchronized, the first network device preferentially selects a non-introduced reachable IP address entry to generate a routing table, which IS helpful for avoiding a loop from occurring in sending an LDP response packet.

In a second aspect, a network device is provided. The network device is a first network device of at least two network devices. The first network device is located in a first area and a second area. The first network device includes: a first link state database, a second link state database and a processing unit.

The first link state database is used for storing link state data of network equipment in the first area.

The second link state database is used for storing link state data of network equipment in the second area.

The processing unit is configured to obtain a first reachable IP address entry set according to the first link state database. Each reachable IP address entry in the first set of reachable IP address entries includes a reachable IP address and a set of region identifications. The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region.

The processing unit is further configured to generate a second reachable IP address entry set according to the first reachable IP address entry set, and add the second reachable IP address entry set to the link state data of the first network device in the second link state database. The generating includes adding an identification of the first region to a set of region identifications for each reachable IP address entry in the first set of reachable IP address entries.

The processing unit is further configured to send a link status packet to a second network device of the at least two network devices. The second network device is located in the second area. The link state packet includes link state data of the first network device in the second link state database to which the second set of reachable IP address entries is added.

Optionally, the generating further comprises deleting reachable IP address entries of the set of area identities that include the identity of the first area from the first set of reachable IP address entries before adding the identity of the first area.

Optionally, the processing unit is further configured to exclude, when generating the routing table of the first network device according to the first link state database and the second link state database, that the area identification set includes the reachable IP address entry of the identification of the first area.

Optionally, the processing unit is further configured to generate a routing table of the first network device using reachable IP address entries in the first link state database and the second link state database that lack a set of area identifications.

The above-described aspects of the second aspect have the same technical effect as the corresponding aspects of the first aspect description using the same means.

In a third aspect, a network device is provided. The network device is a first network device of at least two network devices. The first network device is located in a first area and a second area. The first network device includes a memory, a processor, and a network interface.

The memory is used for storing the first link state database and the second link state database. The first link state database stores link state data for network devices in the first area. The second link state database stores link state data of network devices in the second area.

The processor is configured to obtain a first reachable IP address entry set according to the first link state database. Each reachable IP address entry in the first set of reachable IP address entries includes a reachable IP address and a set of region identifications. The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region.

The processor is further configured to generate a second set of reachable IP address entries according to the first set of reachable IP address entries, and add the second set of reachable IP address entries to the link state data of the first network device in the second link state database. The generating includes adding an identification of the first region to a set of region identifications for each reachable IP address entry in the first set of reachable IP address entries.

The processor is further configured to send a link status packet to a second network device of the at least two network devices through the network interface. The second network device is located in the second area. The link state packet includes link state data of the first network device in the second link state database to which the second set of reachable IP address entries is added.

Optionally, the processor is further configured to exclude, when generating the routing table of the first network device according to the first link state database and the second link state database, that the area identification set includes reachable IP address entries of the identification of the first area.

Optionally, the processor is further configured to generate a routing table of the first network device using reachable IP address entries in the first link state database and the second link state database that lack a set of area identifications.

The above-described aspects of the third aspect have the same technical effects as the corresponding aspects of the first aspect description using the same means.

Drawings

Fig. 1 is a schematic diagram of a possible application scenario provided in an embodiment of the present invention;

fig. 2 is a flowchart of an address transmission method according to an embodiment of the present invention;

fig. 3 is a schematic diagram of a possible application scenario provided in the embodiment of the present invention;

fig. 4 is a structural diagram of a network device according to an embodiment of the present invention;

fig. 5 is a structural diagram of a network device according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a possible application scenario provided in an embodiment of the present invention. The network shown in fig. 1 includes network device R1, network device R2, network device R3, network device R4, and network device R5. The IS-IS protocol IS used in the network. The network includes a first area and a second area. The first area and the second area may be, for example, one area in the network further divided. Network device R1, network device R2, network device R3, and network device R4 are located in a first area, and network device R1, network device R2, and network device R5 are located in a second area. Wherein the network device R1 and the network device R2 are located in both the first area and the second area, i.e. the network device R1 and the network device R2 are located on the border of the first area and the second area. The network device in the IS-IS protocol can be a first-layer (English: Level-1) device, a second-layer (English: Level-2) device or a second-layer (English: Level-1-2) device. The network devices in the same area are devices of the same layer. For example, the network device R1, the network device R2, the network device R3, the network device R4, and the network device R5 are all two-tier devices. Also for example, network device R3 and network device R4 are one tier devices, network device R1 and network device R2 are one two tier devices, and network device R5 is one tier or two tier devices. Also for example, network device R3 and network device R4 are two-tier devices, network device R1 and network device R2 are one-two tier devices, and network device R5 is one-tier or two-tier device.

The network device R1, the network device R2, the network device R3, and the network device R4 in the first area each include a Link State Database (LSDB). The contents of the link state database are kept synchronized among the network devices in the first area through a synchronization mechanism defined by IS-IS. The LSDB of each network device in the first area includes link states of the network device R1, the network device R2, the network device R3, and the network device R4 in the first area. The link status of each network device within the first area may include a reachable IP address entry. The reachable IP address entry describes IP address information that the respective network device can reach. The contents of the LSDB are also kept synchronized among the network device R1, the network device R2, and the network device R5 in the second area through the synchronization mechanism defined by IS-IS. The LSDB of each network device in the second area includes link statuses of the network device R1, the network device R2, and the network device R5 in the second area. The link status of each network device within the second area may include reachable IP address entries describing IP address information reachable by the respective network device. The reachable IP address information includes IP internal reachable information, IP external reachable information, and extended IP reachable information.

Network device R1 and network device R2 are located in both the first area and the second area, each including two LSDBs. One of the LSDBs is synchronized with the LSDBs of the other devices in the first region and the other LSDB is synchronized with the LSDBs of the other devices in the second region. For convenience of description, the LSDB on each network device that is synchronized with the LSDB of the network device in the first area is hereinafter referred to as the first LSDB on each network device, and the LSDB on each network device that is synchronized with the LSDB of the network device in the second area is hereinafter referred to as the second LSDB on each network device.

When the network device R1 performs inter-area route introduction, reachable IP address entries in the link state data of the respective network devices in the first LSDB may be added to the link state data of the network device R1 in the second LSDB, whereby reachable IP address entries of the first area are introduced into the second area. With LSDB synchronization, each network device of the second region will know the reachable IP address entries that can reach the first region via network device R1. When the network apparatus R2 performs inter-area route introduction, reachable IP address entries in the link state data of the respective network apparatuses in the second LSDB may be added to the link state data of the network apparatus R2 in the first LSDB, whereby reachable IP address entries of the second area are introduced into the first area. With LSDB synchronization, each network device of the first region will know the reachable IP address entries that can reach the second region via network device R2. For convenience of description, the reachable IP address entry in the link state data of one network device is simply referred to as the reachable IP address entry of the one network device.

Assuming that network device R1 introduced a reachable IP address entry for network device R4 from the first area into the second area, network device R2 introduced the reachable IP address entry from the second area into the first area, a loop may result. For example, in the case of a failure of a link from the network device R3 to the network device R4, the network device R3 forwards the packet to the network device R4. Since the network device R3 knows the reachable IP address entry of the network device R4 introduced by the network device R2, the network device R3 will send a message to the network device R2. After the message is forwarded in the second area, the message is sent back to the network device R3 by the network device R1. Whereby the introduction of errors in reachable IP address entries causes loops to occur. Network device R1 is aware of the link failure from network device R3 to network device R4 in the first region, but receives an reachable IP address entry for network device R4 introduced by network device R2. The network device R1 will continue to reintroduce the reachable IP address entry for network device R4 introduced by network device R2 into the second region. Due to the above introduction cycle, the loop will always exist.

Multiple area network devices in the ISIS network may be managed using multiple processes. Each network device in the network runs a process for maintaining the LSDB of the network device, and each process is configured with a process identifier of the process. In the case of multiple zones, the processes on the network devices within each zone may be configured with the same process identification. The identification of processes on network devices in different areas is different. A process including a first process identification is run on each network device in the first area. And each network device in the second area runs a process comprising the second process identification. And simultaneously running the process with the first process identification and the process with the second process identification by the network equipment in the first area and the second area. Hereinafter, assuming that the first process is identified as P1, the process having the first process identification is simply referred to as process P1. Assuming that the second process is identified as P2, the process with the second process identification is referred to as process P2 for short. Thus, process P1 and process P2 are provided on network device R1 for maintaining the first LSDB and the second LSDB of network device R1, respectively, and process P1 and process P2 are provided on network device R2 for maintaining the first LSDB and the second LSDB of network device R2, respectively. The embodiment of the invention utilizes the process identifier as the identifier of each area. And adding the identification of the area in the reachable IP address entry of each network device included in the LSDB as the tracking information. When the network equipment positioned at the area boundary performs the inter-area route introduction, the area identification of the reachable IP address entry is identified, which is beneficial to solving the problem of the loop caused by the inter-area route introduction.

Fig. 2 is a flowchart of an address transmission method according to an embodiment of the present invention. The method may be applied to the scenario shown in fig. 1. The method comprises the following steps:

201. the network device R1 obtains a first set of reachable IP address entries from the first link state database, each reachable IP address entry in the first set of reachable IP address entries comprising a reachable IP address and a set of area identifications.

The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region.

For example, network device R1 is located in a first region and a second region, including a first LSDB and a second LSDB. The first LSDB stores link-state data of network devices in the first region, and the second LSDB stores link-state data of network devices in the second region. The reachable IP address entry is, for example, a reachable IP address entry of network device R4.

The set of area identifications may be an empty set, include one area identification, or include multiple area identifications. The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. In the embodiment of the invention, the process identifier running on the network equipment in each area is used as the area identifier. For example, the first and second regions may be identified as P1 and P2, respectively. When the area identifier set comprises a plurality of area identifiers, the reachable IP address entry is introduced multiple times through a plurality of areas. For example, when the area id set of the reachable IP address entry includes the id P1 of the first area, the id P2 of the second area, and the id P3 of the third area, it indicates that the reachable IP address entry has reached the first, second, and third areas, and is finally introduced into the area. When the area identifier set of the reachable IP address entry is an empty set, that is, when no area identifier is included in the reachable IP address entry, it indicates that the reachable IP address entry is not imported from another area. For example, the reachable IP address entry of network device R4 in the first area, when not being pulled out, does not contain an area id, and the area id set thereof is an empty set.

The network device R1 may obtain the first set of reachable IP address entries from the first LSDB either directly or in steps. The direct acquisition means that when the network device R1 reads the reachable IP address entry in the first LSDB, it sets a restriction condition that the area identifier set does not include the identifier of the second area, thereby directly acquiring the first reachable IP address entry set. Step acquisition means that the network device R1 first reads all reachable IP address entries in the first LSDB. The network device R1 then extracts reachable IP address entries for which the set of area identifications does not include the identification of the second area among all reachable IP address entries to obtain the first set of reachable IP address entries. Or the network device R1 deletes reachable IP address entries for which the set of area identifications includes the identification of the second area among all reachable IP address entries to obtain the first set of reachable IP address entries.

202. Network device R1 generates a second set of reachable IP address entries from the first set of reachable IP address entries, adds the second set of reachable IP address entries to the link state data of network device R1 in the second link state database, the generating including adding the identity of the first region to a set of region identities for each reachable IP address entry in the first set of reachable IP address entries.

For example, network device R1 adds the identity of the first zone, P1, to the set of zone identities of the reachable IP address entries of network device R4. The reachable IP address entry for the added identity P1 is added to the link state data for network device R1 for the second LSDB on network device R1. Thus, when the inter-area route is introduced, the area identification of the area through which the reachable IP address entry passes is saved in the reachable IP address entry. The area identifier is used as a kind of tracking information, and may indicate that the reachable IP address entry is obtained through the network device in the area identified by the area identifier. Therefore, the network equipment can identify the area passed by the reachable IP address entry in the introduction of the reachable IP address entry, and the condition that the introduced reachable IP address entry is introduced back to the already-reached area is avoided. The scheme is helpful for simply solving the problem that the loop is introduced by the inter-area route.

Optionally, the generating further comprises deleting reachable IP address entries of the set of area identities that include the identity of the first area from the first set of reachable IP address entries before adding the identity of the first area. The deletion has the effect of preventing loops in certain misconfiguration scenarios. For example, the interface of network device R2 in the scenario of fig. 1 is misconfigured. One process on network device R2 is configured to use two interfaces connected to network device R3 and network device R5. The LSDB of the network device in the first area is error-synchronized with the LSDB of the network device in the second area. Where network device R1 introduces reachable IP address entries for network device R4 into the second LSDB, each device in the second region knows that network device R1 has reachable IP address entries for network device R4. After the mis-synchronization, the network device R3 learns the synchronization information of the network device R1 in the second area, i.e., the network device R1 has the reachable IP address entry of the network device R4. When the link from the network device R3 to the network device R4 in the first area is broken, the network device R3 forwards the message addressed to the reachable IP address of the network device R4 to the network device R1. Network device R1, while aware of the link failure from network device R3 to network device R4 within the first area, continues to receive reachable IP address entries for network device R4 that were miscynchronized from the second area back to the first area and continues to introduce the reachable IP address entries to the second area. Because of the above reachable IP address entry introduction loop, the network device R3 continues to forward the message addressed to the reachable IP address of the network device R4 to the network device R1. This problem can be helped to be prevented if the network device R1 recognizes the identity of the first region in the reachable IP address entry. In the event of the interface misconfiguration, the network device R1 deletes the reachable IP address entry that already includes the identity of the first region from the first set of reachable IP address entries before adding the identity of the first region to the reachable IP address entries in the first set of reachable IP address entries. Thus, the network device R1 does not re-bring out reachable IP address entries that already include the identity of the first region, helping to avoid messaging problems caused by miscynchronization.

Optionally, when each network device in the first area generates a routing table according to its own included link state database, the reachable IP address entry whose area identifier set includes the identifier of the first area is excluded. In the interface misconfiguration case, the reachable IP address entries learned by network device R1 and network device R3 for the second zone each include an identification of the first zone. Network device R1 may exclude reachable IP address entries that include the first zone identification when calculating local routes from the first LSDB and the second LSDB. Network device R3 may exclude reachable IP address entries that include the first zone identification when calculating local routes from the first LSDB. By excluding reachable IP address entries including the first zone identification, it is helpful to avoid the problem of message sending caused by wrong synchronization.

203. The network device R1 sends a link status message to the network device R5 in the second area.

The link state message includes link state data of the network device R1 in the second link state database to which the second set of reachable IP address entries is added. The network device R1 sends a link status message to the network device R5 for synchronization of the LSDB of the second region.

Optionally, the link status packet carries the set of the area identifiers in a type-length-value (TLV) manner. RFC5305, for example, provides an extension to the IS-IS protocol by which a set of zone identities can be added to a link state message. RFC5305 provides that a plurality of extended IP reachable TLVs with type 135 may be included in the link-state message. Each type 135 extended IP reachable TLV may be used to carry a reachable IP address entry including, among other things, reachable IP addresses and metric values, such as cost. The type 135 extended IP reachable TLV may include a plurality of sub-TLVs. Each sub-TLV includes a type, a length, and a value of the sub-TLV. In this embodiment, one sub-TLV may be used to carry the area identifier. For example, a sub-TLV is selected with a type of 81 and a length of 4 × N bytes, and N region identifiers are encapsulated in the value part, wherein each region identifier occupies 4 bytes.

204. Network device R5 receives the link state message from network device R1.

The network device R5 obtains the link state data of the network device R1 from the link state message, and stores the link state data in the link state database of the network device R5.

Optionally, the network device R5 generates a routing table according to its own link state database, that is, the second LSDB, and the network device R5 receives the data packet to be forwarded, obtains the destination address of the data packet, obtains the address of the next hop network device from the routing table according to the destination address, and forwards the data packet to the next hop network device. The destination address may comprise the reachable IP address in the reachable IP address entry introduced by network device R1.

205. The network device R5 sends the link status message including the link status data of the network device R1 to the network device R2.

The link state message includes link state data of the network device R1 to which the second set of reachable IP address entries is added.

206. Network device R2 receives the link state message from network device R5.

The network device R2 obtains the link state data of the network device R1 from the link state message, and stores the link state data in the link state database of the network device R2. Network device R2 identifies that the various fields in the link state data of network device R1 are saved into the second LSDB of network device R2. Whereby network device R2 stores the second set of reachable IP address entries in a second LSDB. For example, the network device R2 obtains an extended IP reachable TLV with a type of 135 from the link status packet, and obtains the reachable IP address and the metric value in the reachable IP address entry from the extended IP reachable TLV. The network device R2 further obtains a sub-TLV with type 81 from the extended IP reachable TLV, and obtains the area identifier in the sub-TLV. The network device R2 saves the reachable IP addresses, the metric values, and the area identifications of the above reachable IP address entries, etc. into the second LSDB of the network device R2.

207. Network device R2 obtains a third set of reachable IP address entries from the second LSDB, each reachable IP address entry in the third set of reachable IP address entries comprising a reachable IP address and a set of area identifications.

The area identifier in the area identifier set indicates that the reachable IP address entry is obtained via the network device in the area identified by the area identifier, and the area identifier set of any reachable IP address entry in the third reachable IP address entry set does not include the identifier of the first area.

The operation performed by the network device R2 in 207 is similar to that performed by the network device R1 in 201, and the same contents are not repeated herein. The reachable IP address entries that network device R1 introduced from the first area to the second area all include the identity of the first area and therefore will not enter the third set of reachable IP address entries. Therefore, the method avoids introducing the extracted reachable IP address entry back to the already-arrived area, and is beneficial to simply solving the problem of loop caused by the introduction of the inter-area route.

208. Network device R2 generates a fourth set of reachable IP address entries from the third set of reachable IP address entries, adds the fourth set of reachable IP address entries to the link state data of network device R2 of the first LSDB of network device R2, the generating including adding the identity of the second region to a set of region identities for each reachable IP address entry in the third set of reachable IP address entries.

The operations performed by the network device R2 in 208 are similar to those performed by the network device R1 in 202, and the same contents are not repeated herein.

209. The network device R2 sends a link status message to the network device R3 in the first area.

The link state message includes the link state data of the network device R2 in the first link state database to which the fourth set of reachable IP address entries is added.

The operation performed by the network device R2 in 209 is similar to the operation performed by the network device R1 in 203, and is not described again.

210. Network device R3 receives the link state message from network device R2.

The network device R3 obtains the link state data of the network device R2 from the link state message, and stores the link state data in the link state database of the network device R3.

The operation performed by the network device R3 in 210 is similar to the operation performed by the network device R5 in 204, and is not described again.

211. The network device R3 generates a routing table according to its own link state database, and forwards a message according to the routing table.

The network device R3 receives a data packet to be forwarded, obtains a destination address of the data packet, obtains a next hop network device address from the routing table according to the destination address, and forwards the data packet to a next hop network device. The destination address may comprise the reachable IP address in the reachable IP address entry introduced by network device R2.

In the above process, the network device R1 and the network device R2 identify the set of area identifications in the reachable IP address entry when making the reachable IP address entry. Reachable IP address entries led out of one area can not be led into the area any more, which is helpful for solving the problem that the routing leading-in between the areas has a loop. In addition, the solution does not need to be customized according to different networks, and different control strategies do not need to be configured on each network device for implementation and introduction, so that the possibility of wrong configuration is reduced. Under the condition that the network area division is complex, the method is beneficial to simply solving the problem that the loop is introduced by the inter-area route.

The above introduced scheme of reachable IP address entries may encounter another loop problem in some scenarios. For example, in fig. 3, a network with a special scenario exists, in which a Label Distribution Protocol (LDP) and an IS-IS Protocol synchronization mechanism are used. The network device R1 and the network device R2 are located in the first area and the second area. The first area and the second area may be, for example, one area in the network further divided. The network device R3 is located only in the first area. The network device R5 is located only in the second area. Both network device R1 and network device R2 are configured to introduce reachable IP address entries for the first region into the second region. In the LDP and IS-IS protocol synchronization mechanisms, the overhead of the reachable IP address entry IS set to a fixed value, e.g., 10000, after the reachable IP address entry IS introduced. Both network device R1 and network device R2 can obtain the reachable IP address entry for network device R3 from the link state data for network device R3. If network device R2 introduced the reachable IP address entry for network device R3 from the first LSDB into the second LSDB. Then, through LSDB synchronization, the link state data of network device R2 would include the reachable IP address entry of network device R3 in the second LSDB of network device R1. Network device R1 knows through the second LSDB that network device R2 has an reachable IP address entry for network device R3 and the overhead is 10000. When the link from the network device R3 to the network device R1 is broken and reconnected, the network device R3 sends an LDP initialization message to the network device R1. The network device R3 needs to return a response message to the network device R1, thereby reestablishing the LDP connection. In the LDP and IS-IS synchronization mechanisms, the overhead of the network device R3 to network device R1 link during LDP connection establishment IS set to a maximum, e.g., 1677214. At this point the cost of the reachable IP address entry for network device R3 in the first LSDB of network device R1 is a maximum of 1677214. As previously described, in performing reachable IP address entry introduction, the overhead of the reachable IP address entry of network device R3 in the link state data of network device R2 in the second LSDB of network device R2 is always a fixed value of 10000. Thus, with LSDB synchronization, network device R1 includes reachable IP address entries for network device R3 with an overhead of 1677214 in the first LSDB and reachable IP address entries for network device R3 belonging to link state data for network device R2 with an overhead of 10000 in the second LSDB. Network device R1 will select the reachable IP address entry for network device R3 that is less expensive to belong to the link state data of network device R2. Thus, the network device R1 sends a reply message to the network device R2. After receiving the response message, the network device R2 sends the response message back to the network device R1 according to the reachable IP address entry of the network device R3 in the first LSDB. Whereby a loop occurs.

Optionally, network device R1 generates a routing table for network device R1 using reachable IP address entries in the first LSDB and the second LSDB that lack the set of zone identifications. The reachable IP address entry lacking the area identifier set refers to a reachable IP address entry not including the area identifier set, or refers to a reachable IP address entry whose area identifier set is an empty set, that is, the area identifier set does not include the area identifier. And the reachable IP address entries lacking the area identification sets are not introduced or led out through the reachable IP address entries. Thus for the LDP and IS-IS synchronization scenario described above, the network device R1 generates a routing table using reachable IP address entries in the first LSDB and the second LSDB that lack sets of zone identifications. That is, when the network device calculates the local route, the reachable IP address entry of the network device R3 with the overhead of 10000 is excluded, and the reachable IP address entry with the overhead of 1677214 is selected. Therefore, the network device R1 returns a response message to the network device R3 according to the reachable IP address entry with the overhead of 1677214, thereby implementing the establishment of LDP connection. Since the routing table is generated by using the reachable IP address entries of the set without the area identifier, the introduced reachable IP address entries are excluded, so that the network device R1 can reuse the link with the largest overhead to send the response message. Therefore, the network device R1 sends a response message to the network device R3 based on the routing table, and the LDP connection is successfully established. The network device R1 only uses reachable IP address entries lacking the area identification set in the routing calculation, and excludes the introduced reachable IP address entries, which helps to avoid loops in sending LDP reply messages. The successful sending of the LDP response message enables the network to realize the synchronization of the LDP protocol and the IS-IS protocol.

Fig. 4 is a block diagram of a network device 400 according to an embodiment of the present invention. The network device 400 may be used to perform the methods performed by the network device R1 or the network device R2 in the embodiments corresponding to fig. 1-3. Network device 400 is a first network device 400 of at least two network devices. The first network device 400 is located in a first area and a second area. The first area and the second area may be, for example, a further division of an area in the network. The first network device 400 includes: a first link state database 401, a second link state database 402 and a processing unit 403. The processing unit 403 is connected to a first link state database 401. The processing unit 403 is connected to a first link state database 402.

A first link state database 401, configured to store link state data of network devices in the first area.

A second link state database 402 for storing link state data of network devices in said second area.

A processing unit 403, configured to obtain a first set of reachable IP address entries according to the first link-state database 401. Each reachable IP address entry in the first set of reachable IP address entries includes a reachable IP address and a set of region identifications. The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region.

The processing unit 403 is further configured to generate a second set of reachable IP address entries according to the first set of reachable IP address entries, and add the second set of reachable IP address entries to the link state data of the first network device 400 in the second link state database 402. The generating includes adding an identification of the first region to a set of region identifications for each reachable IP address entry in the first set of reachable IP address entries.

The processing unit 403 is further configured to send a link status packet to a second network device of the at least two network devices. The second network device is located in the second area. The link state packet includes link state data of the first network device 400 in the second link state database 402 to which the second set of reachable IP address entries is added.

Optionally, the processing unit 403 is further configured to exclude the reachable IP address entry whose area identifier set includes the identifier of the first area when generating the routing table of the first network device 400 according to the first link state database 401 and the second link state database 402.

Optionally, the processing unit 403 is further configured to generate a routing table of the first network device 400 using reachable IP address entries of the first link state database 401 and said second link state database 402 that lack the set of area identifications.

In fig. 4, the first link state database 401, the second link state database 402 and the processing unit 403 may be implemented by functional components generated after a processor reads software codes stored in a memory and runs, or may be implemented by hardware units.

Fig. 5 is a block diagram of a network device 500 according to an embodiment of the present invention. Network device 500 is a first network device 500 of at least two network devices. The first network device 500 may be a router or other type of network device having route calculation and message forwarding functions. The first network device 500 may be used to perform the method performed by the network device R1 or the network device R2 in the embodiments corresponding to fig. 1-3. The first network device 500 may be used to implement the functionality of the first network device 400 in the corresponding embodiment of fig. 4. The first network device 500 is located in a first area and a second area. The first area and the second area may be, for example, a further division of an area in the network. The first network device 500 includes a memory 501, a processor 502, and a network interface 503. The processor 502 is connected to the memory 501 for storing and reading data. The processor 502 is also connected to the network interface 503, and controls the network interface 503 to receive and transmit messages or commands.

A memory 501 for storing a first link state database and a second link state database. The first link state database stores link state data for network devices in the first area. The second link state database stores link state data of network devices in the second area.

A processor 502 configured to obtain a first set of reachable IP address entries from the first link state database. Each reachable IP address entry in the first set of reachable IP address entries includes a reachable IP address and a set of region identifications. The area identifier in the area identifier set indicates that the reachable IP address entry is acquired via the network device in the area identified by the area identifier. The set of region identifications for any one reachable IP address entry in the first set of reachable IP address entries does not include an identification of the second region.

The processor 502 is further configured to generate a second set of reachable IP address entries according to the first set of reachable IP address entries, and add the second set of reachable IP address entries to the link state data of the first network device 500 in the second link state database. The generating includes adding an identification of the first region to a set of region identifications for each reachable IP address entry in the first set of reachable IP address entries.

The processor 502 is further configured to send a link status message to a second network device of the at least two network devices through the network interface 503. The second network device is located in the second area. The link state packet includes the link state data of the first network device 500 in the second link state database to which the second set of reachable IP address entries is added.

Optionally, the processor 502 is further configured to exclude the reachable IP address entry where the area identifier set includes the identifier of the first area when generating the routing table of the first network device 500 according to the first link state database and the second link state database.

Optionally, the processor 502 is further configured to generate a routing table of the first network device 500 using reachable IP address entries of the first link state database and the second link state database that lack the set of area identifications.

The processor 502 may be a Central Processing Unit (CPU), a Network Processor (NP), or a combination of a CPU and an NP.

The memory 501 may include a volatile memory (RAM), such as a random-access memory (RAM). The memory 501 may also include a non-volatile memory (SSD), such as a read-only memory (ROM), a flash memory (flash memory), a hard disk (HDD), or a solid-state drive (SSD). The memory 501 may also comprise a combination of memories of the kind described above.

Alternatively, the memory 501 may be integrated into the processor 502 as an internal component of the processor 502.

The network interface 503 may be an ethernet interface, an Asynchronous Transfer Mode (ATM) interface, or a SDH/SONET based wrapper (POS) interface.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An address transmission method, wherein a first network device is located in a first area and a second area, the first network device includes a first link state database and a second link state database, the first link state database stores link state data of network devices in the first area, the second link state database stores link state data of network devices in the second area, the method comprising:

the first network device acquires a first reachable Internet Protocol (IP) address entry set according to the first link state database, wherein each reachable IP address entry in the first reachable IP address entry set comprises a reachable IP address and a region identification set, a region identification in the region identification set is used as tracking information to indicate that the reachable IP address entry is acquired by the network device in the region identified by the region identification, and the region identification set of any reachable IP address entry in the first reachable IP address entry set does not comprise the identification of the second region;

the first network device generates a second reachable IP address entry set according to the first reachable IP address entry set, adds the second reachable IP address entry set to the link state data of the first network device in the second link state database, and the generating includes adding the identifier of the first area to an area identifier set of each reachable IP address entry in the first reachable IP address entry set;

the first network device sends a link state message to a second network device in the second area, where the link state message includes link state data of the first network device in the second link state database to which the second reachable IP address entry set is added, so that a third network device does not send a reachable IP address entry including the first area identifier to a network device in the first area, the third network device is located in the first area and the second area, and link state databases of the third network device and the second network device are kept synchronized.

2. The method of claim 1, wherein the generating further comprises deleting a set of area identifications from the first set of reachable IP address entries before adding the identification of the first area, reachable IP address entries for which the set of area identifications includes the identification of the first area.

3. The method of claim 1 or 2, wherein the method further comprises:

and when the first network equipment generates a routing table of the first network equipment according to the reachable IP address entries in the first link state database and the second link state database, excluding the reachable IP address entries of which the area identification set comprises the identification of the first area.

4. The method of claim 1, wherein the method further comprises:

the first network device generates a routing table for the first network device using reachable IP address entries in the first link state database and the second link state database that lack a set of area identifications.

5. A network device, wherein the network device is a first network device of at least two network devices, wherein the first network device is located in a first area and a second area, wherein the first network device comprises:

a first link state database for storing link state data of network devices in the first area;

a second link state database for storing link state data of network devices in the second area;

a processing unit to:

acquiring a first reachable Internet Protocol (IP) address entry set according to the first link state database, wherein each reachable IP address entry in the first reachable IP address entry set comprises a reachable IP address and a region identification set, a region identification in the region identification set is used as tracking information to indicate that the reachable IP address entry is acquired by network equipment in a region identified by the region identification, and the region identification set of any reachable IP address entry in the first reachable IP address entry set does not comprise an identification of the second region;

generating a second set of reachable IP address entries from the first set of reachable IP address entries, adding the second set of reachable IP address entries to the link state data of the first network device in the second link state database, the generating including adding the identity of the first region to a set of region identities for each reachable IP address entry in the first set of reachable IP address entries;

sending a link state message to a second network device of the at least two network devices, the second network device being located in the second area, the link state message including link state data of the network device in the second link state database to which the second reachable IP address entry set is added, so that a third network device does not send a reachable IP address entry including the first area identifier to a network device in the first area, the third network device being located in the first area and the second area, and link state databases of the third network device and the second network device being kept synchronized.

6. The network device of claim 5, wherein the generating further comprises deleting reachable IP address entries from the first set of reachable IP address entries that have an area identification set that includes an identification of the first area prior to adding the identification of the first area.

7. The network device of claim 5 or 6, wherein the processing unit is further to:

and when the routing table of the first network equipment is generated according to the first link state database and the second link state database, excluding a reachable IP address entry of which the area identification set comprises the identification of the first area.

8. The network device of claim 5, wherein the processing unit is further to:

generating a routing table for the first network device using reachable IP address entries in the first link state database and the second link state database that lack a set of area identifications.

9. A network device, wherein the network device is a first network device of at least two network devices, the first network device being located in a first area and a second area, the first network device comprising a memory, a processor, and a network interface, wherein,

the memory is used for storing a first link state database and a second link state database, the first link state database stores the link state data of the network equipment in the first area, and the second link state database stores the link state data of the network equipment in the second area;

the processor is configured to:

sending a link state message to a second network device of the at least two network devices through the network interface, where the second network device is located in the second area, the link state message includes link state data of the first network device in the second link state database to which the second reachable IP address entry set is added, so that a third network device does not send a reachable IP address entry including the first area identifier to a network device in the first area, the third network device is located in the first area and the second area, and link state databases of the third network device and the second network device are kept synchronized.

10. The network device of claim 9, wherein the generating further comprises deleting reachable IP address entries from the first set of reachable IP address entries for which a set of area identifications includes an identification of the first area, prior to adding the identification of the first area.

11. The network device of claim 9 or 10, wherein the processor is further configured to:

12. The network device of claim 9, wherein the processor is further configured to: