JP2002368788A - Method and system for interconnecting path control domain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for interconnecting AS(Autonomous Systems) via an IXP(Internet eXchange Point) provided with expandability independently of a 2nd layer with less cost in the AS. SOLUTION: The method for interconnecting the AS via the IXP 10 with an interface by an IP layer formed thereto, includes a step for connecting the two AS12-1, 12-2 desiring mutual communication to the IXP 10 to allow the AS12-1 12-2 to exchange path information as an IP layer policy, a step for generating an MPLS(Multi-Protocol Label Switching) label having information denoting the IP layer policy including at least a routing policy in the AS12-1 being a sender to add the label to a packet to the transmitted, a step for extracting the label from the packet at the IXP 10 to analyze the IP layer policy indicated in the label and identifying a transfer destination of the packet according to the IP layer policy, and a step for transferring the packet to the AS12-2 being the transfer destination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for interconnecting a plurality of different routing control domains (Autonomous Systems: AS).

[0002]

2. Description of the Related Art An IXP (Intern) for interconnecting ASs so that a plurality of different ASs can communicate with each other by IP.
et eXchange Point). This IXP is available from ASs such as Internet Service Providers (ISPs).
Are connected via a high-speed switch to facilitate data communication between ISPs.

[0003] Normally, a unique policy (such as a routing policy) in the IP layer is set in the AS. Therefore, in order to interconnect different ASs, for example, two ASs, it is necessary to arbitrate and set policies between ASs.

[0004]

For this reason, the conventional IX
In P, a layer lower than the IP layer (for example, Ethernet (registered trademark), ATM (Asynchronous), so as not to be involved in the set policy of the IP layer between ASs.
layer 2 such as ous Transfer Mode), FR (Frame Relay)
Technology) as an interface or network for interconnection. Therefore, there is a problem that an AS who wants to connect via the IXP needs to use the layer 2 technology adopted by the IXP. For example, as shown in FIG. 5, the conventional IXP 100 employs Ethernet as the layer 2 technology. Therefore, the two ASs 102-1 and 102-2 (referred to as AS1 and AS2, respectively, in FIG. 5) that require interconnection through the IXP 100 both use Ethernet (registered trademark). IX
Must be connected to P. In addition, IXP has a plurality of AS
Large-scale A because it is intended to interconnect
It is located in the metropolitan area where S exists.

[0005] When an AS located at a point far from the IXP desires interconnection between the ASs via the IXP, a communication path to the IXP must be secured using a dedicated line or the like. However, this is a factor that increases the communication cost. In addition, IXP uses Ethernet as Layer 2
When (registered trademark) is adopted, there is a problem in scale expandability. According to Ethernet (registered trademark), E
The trouble of some machines connected to the Ethernet (registered trademark) may be widespread. Also, one Et
Hernet (registered trademark) is operated by allocating a very limited range of IP addresses, so the number of connected hosts and nodes is limited.
Configuration changes on hosts and nodes are also required.

On the other hand, when ATM is used as the layer 2, a path that specifies one-to-one connection between a host and a node must be set by an ATM switch, and this procedure is complicated. There is a problem. Therefore, an AS that covers a wide area, that is, an AS that is arranged in a wide area
However, there is a problem in that an IXP for interconnecting cannot be constructed.

[0007] It is an object of the present invention to provide a method of interconnecting ASs via an IXP that does not depend on the second layer, has a low cost burden on the AS, and has expandability.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for connecting a plurality of routing domains via an interconnection network having an interface formed by an IP layer.
Two routing domains wishing to communicate with each other connecting to an interconnection network; exchanging routing information as an IP layer policy between the two routing domains; Generating an MPLS label having information indicating at least an IP layer policy including a routing policy in a control domain and adding the label to an outgoing packet; and extracting a label from the packet in an interconnection network, Analyzing the indicated IP layer policy; identifying a transfer destination of the packet according to the analyzed IP layer policy; and transferring the packet to the other routing domain which is the identified transfer destination Interconnecting routing domains, comprising: It is achieved by the method.

According to the invention, in an interconnection network, M
The destination of the packet described using the PLS label is referred to, and the packet is transferred with respect to this destination. That is, it is possible to form an LSP (Label Switched Path) that can carry a packet in the IXP according to the layer policy of the AS that performs mutual communication via the IXP. Therefore, the IP layer interface (layer 3
(Interface) using an interface, and the AS can communicate with each other through this network. For example, in the step of exchanging route information, BGP-4 is used.

[0010] In a preferred embodiment, M further comprises information indicating an IP layer policy including a policy regarding traffic volume and / or traffic handling.
Generating a PLS label and adding the label to a packet to be transmitted. This makes it possible to set the upper limit of the traffic volume. In addition, by including a policy regarding the handling of traffic, it becomes possible to apply a policy of, for example, treating a packet with a label as priority / non-priority or guaranteeing the packet as a lower limit.

In a preferred embodiment of the present invention, the method further comprises the step of counting the number of labeled packets in the interconnection network. As a result, in the IXP, it becomes possible to charge the AS according to the total amount of packets.

Another object of the present invention is to provide an IP network as an interconnecting network interposed in data communication of a plurality of routing control domains.
An interconnecting device forming an interface by layers, and a route information transmitting process for executing a process for transmitting route information from two routing control domains desired to communicate with each other to a routing control domain of a communication partner. Means and in one of the source routing domains,
Layer policy analysis means for receiving a packet to which an MPLS label having information indicating an IP layer policy including a routing policy is added, extracting a label from the packet, and analyzing the IP layer policy into the label; An interconnect comprising: a packet transfer unit that specifies a packet transfer destination according to the IP layer policy analyzed by the analysis unit and transfers the packet to the other routing domain that is the transfer destination. Achieved by the device.

In a preferred embodiment, the apparatus further comprises packet counting means for counting the number of packets to which the label has been added, and the total amount of transmitted and / or received packets is grasped for each of the routing control domains. In the above embodiment, the interconnection network can also function as a routing domain.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram schematically showing an inter-AS communication system according to an embodiment of the present invention. As shown in FIG. 1, in this communication system, an IXP 10 employing a layer 3 interface is provided. Therefore, IXP
At 10, what layer 2 interface
Whether to connect to XP10 is not specified. Therefore, for example, AS12-1 (denoted as "AS1" in the drawing) and AS12-2 (denoted as "AS2" in the drawing) respectively adopt a desired layer 2 interface. Can be. For example, AS12-1
However, as a layer 2 interface, Ethernet
, While the AS 12-2 may employ PPP as the layer 2 interface. In addition,
In this specification, “AS” means a route control range that is managed by the same operation manager. Therefore, AS includes ISPs, networks of universities, ministries, and local governments.

As shown in FIG. 1, the AS 12 is provided with an IP layer policy adding device 16 for realizing such an interconnection.
The packet is sent to the external network via the layer policy adding device 16. In the present embodiment, IXP10
Also has a function as an AS (in FIG. 1,
"IXP (AS3)"), IP router 1
8 is provided. In addition, the IXP (AS3) 10
Layer policy protection device 20 for protecting the layer policy added in AS 12-1 and AS 12-2
have. In FIG. 1, the IP routers 18-1 and 18-2 are connected to both the side connected to the AS 12-1 and the side connected to the AS 12-2, respectively.
And the layer policy protection devices 20-1 and 20-2 are arranged. In practice, however, it is not necessary to provide a plurality of routers and the layer policy protection device, and a single router and the layer policy protection device are used. , Are connected to a plurality of ASs via a network.

For example, as shown in FIG. 2A, a plurality of ASs (ASs 12-1, 12-2, 12-4, 12-
5 and IXP (AS3) 10 are connected, and AS12-1 and 12-2 are newly
A description will be given of a procedure for using the AS3 as an IXP when interconnecting.

First, AS12-1 and AS12-2
Connect to use the IXP (AS3) 10 as an interconnection network, and then exchange path information as a mutual IP layer policy between the AS 12-1 and the AS 12-2 (FIG. 2 (b) )) 201). The exchange of the routing information is actually performed by BGP-4 (Border Gateway P
A routing protocol called rotocol Version 4) is used. When the ASs are interconnected, the layer policy of the partner is often different from that of the AS. For example, the type of IP address to which the route information to the network is to be advertised, the route information from which AS is to be advertised, and whether only the route information of the own AS is to be advertised are different between ASs. . Therefore, IP which is inconvenient for oneself
It is necessary to arbitrate the layer policy between the ASs so that the packets are not transmitted from the AS on the other side while receiving convenient IP packets. More specifically,
When exchanging IP layer policies (exchanging route information), the following information is exchanged.

Reachable IP address (prefix) information: NLRI (Network Layer Reachability)
information) Information indicating what route the AS has traveled: AS
_PATH Information indicating what priority is handled: Information indicating where the MED packet should be sent: Next_H
op

Thus, AS12-1 and AS12
-2, the route information is exchanged, for example, AS
12-1 sends an IP packet for AS12-2 to IX
P (AS3) 10 can be transmitted. However, when the IP packet passes through the IXP (AS3) 10, the IP packet may be carried according to the layer policy of the IXP (AS3) 10. Because, here, the IXP (AS3) 10 functions as the IXP, so that the AS12-1 or the AS12-2
Is not involved in this layer policy.

For example, if IXP (AS3) 10
If the IP packet for 12-2 has a layer policy of transmitting to AS5, AS12-1
The IP packet transmitted from the to the IXP (AS3) 10 is transferred to the AS5. For this reason, AS12-
There is a possibility that the flow of the IP packet intended by 1 and the flow of the actual IP packet may be different.

Therefore, in the present embodiment, in order to protect the policy of the AS to be interconnected, an AS that wants to be interconnected with another AS via IXP is provided with a layer policy adding device 16. AS functioning as IXP
Has at least a layer policy protection device 20.

Thus, in the connection between ASs, packet transfer according to the policy of the AS becomes possible. Specifically, the addition of the layer policy and the protection thereof are realized by using MPLS (Multi-Protocol Label Switching) technology. MPLS is specified using 20 bits of a label (shim header) which is a 32-bit information field provided between a data link layer (layer 2) header and a network layer (layer 3) header. It realizes packet transfer to the specified route.

Therefore, the layer policy adding device 16 according to the present embodiment generates a label based on the AS layer policy and adds the label to the packet. On the other hand, the IXP layer policy protection device 20 extracts the label from the received packet, analyzes the contents of the label, and transfers the packet accordingly.

FIG. 3 is a flowchart showing the outline of such data communication. FIG. 3 shows that AS12-1
The case where it is desired to transmit data toward S12-2 is shown. As shown in FIG. 3, here, the layer policy adding apparatus 16-1 of the AS 12-1 has the AS 12-1 as the AS 1
A label including information indicating the accepted IP layer policy is generated from step 2-2 (step 301), and the generated label is added between the layer 2 header and the layer 3 header (step 302).

The packet with the label is IXP
(AS3) Accepted by the layer policy protection device 20 of step 10 (step 303). Layer policy protection device 20
Extracts the label in the packet and analyzes its contents (step 304). As a result, the packet is transferred to a predetermined destination according to the layer policy of the AS 12-1 (Steps 305 and 306). In this way, the route according to the AS 12-2 policy
The packet is accepted by 12-2 (step 30).
7).

IX from AS12-2 to AS12-1
The same processing is executed for packet transmission via P (AS3) 10, and the layer policy protection device 20 of IXP (AS3) 10 transmits the label added by the layer policy addition device 16-2 of AS 12-2. Is analyzed, and based on this, data transfer is performed in consideration of the AS2 layer policy.

As described above, in the present embodiment, I
When the ASs are interconnected via the XP (AS3), packets can be transmitted according to the AS's policy. The packet from the AS 12-1 includes
As long as the label is within the IXP (AS3) 10, the above-described label needs to be added. This is IXP (AS3)
IXP (AS3) 1 because 10 comprises a plurality of nodes
In the case of 0, if there is no label, the policy between ASs will be lost on the way. In other words, in the IXP (AS3), the analysis of the label (see step 304 in FIG. 3) is executed every time the packet passes through the node.

As shown in FIG. 4, in the present embodiment, a label is added to a packet by the layer policy adding device 16-1 of the AS 12-1, and the packet is
(AS3) It is transmitted to 10. IXP (AS3) 10
Has a layer policy protection device 20,
The layer policy of the XP (AS3) 10 itself is
-2, the packet is forwarded to the AS 12-5 according to the information included in the label and indicating the IP layer policy accepted by the AS-1 from the AS-2, even though the packet indicates that the packet goes through the AS 12-5. Without being performed (reference numeral 402), and is directly transferred to the AS 12-2 (reference numeral 401).

According to the present embodiment, during IXP, an LSP (Label Switched) capable of carrying a packet according to an AS layer policy for mutual communication via the IXP.
Path) can be formed. This makes it possible to realize packet transfer according to the interconnection policy.

Further, according to the present embodiment, connection to IXP is possible regardless of the type of the layer 2 interface employed by the AS. Thus, the interconnection between ASs via IXP can be enhanced. In addition, since the IXP can be constructed using the layer 3 interface, it has the same expandability as the Internet and can be distributed. Therefore, the AS can select an IXP that is geographically close when interconnecting with another AS via the IXP. Thereby, AS by distance between AS and IXP
It is possible to reduce the cost difference between them.

Further, in this embodiment, by constructing the IXP using the IP layer, it is possible to solve the problem of the scalability of the conventional IXP using the layer 2 technology. Thus, it is possible to provide a plurality of options for the type of the interface for interconnection.

By describing the policy regarding the traffic volume in a label, it becomes possible for IXP to charge the AS according to this policy. Conventional I
In XP, a charge imposed on an AS is determined according to a transmission speed of a port to be established (for example, 100 Mbps or 1 Gbps).

According to the present embodiment, in IXP,
The total amount of labeled packets is counted, and a tariff is applied to the count value to determine the amount. By enabling charging according to the packet amount, it is possible to construct a more reasonable fee system for both AS and IXP. The present invention
Without being limited to the above embodiments, various changes can be made within the scope of the invention described in the claims, and it is to be understood that they are also included in the scope of the present invention. Needless to say.

For example, in the above embodiment, I
Although the XP also has the AS function, it is not limited to this, and it goes without saying that the XP may be an IXP that does not have the AS function.

In the above embodiment, the routing policy is described in the label and the label is added to the packet. However, the items described in the label are not limited to this. For example, a configuration may be adopted in which a policy regarding the traffic volume between ASs is set. For example, for an AS, physically 10 Mb
ps interface, but 1Mbps
With the above, it can be set that no traffic flows. In addition, setting for each time, for example, 8:00 to 2
1 Mbps at 3:00, 1 at 23:00 to 8:00
Settings such as 0 Mbps are also possible. Furthermore, by describing a policy regarding traffic handling in a label, for example, priority / non-priority handling of a packet to which a label is added, assurance as a lower limit value, and the like may be set.

Further, in the above embodiment, the AS
When transmitting a packet from 12-1 to AS 12-2,
AS12-1 includes AS12 in the label attached to the packet.
-2 includes, but is not limited to, the IP layer policy accepted. For example, a label that includes the IP layer policy of the transmission source AS 12-1 itself may be added to the packet. In this specification, the function of one unit may be realized by two or more physical units, or the function of two or more units may be realized by one physical unit.

[0037]

According to the present invention, A is independent of the second layer.
It is possible to provide an interconnection method between ASs via IXP, which has a low cost burden on S and has scalability.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an inter-AS communication system according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a process in performing mutual communication between two ASs in the present embodiment.

FIG. 3 shows two ASs in the present embodiment.
4 is a flowchart showing an outline of data communication via IXP during the communication.

FIG. 4 shows two ASs in the present embodiment.
FIG. 2 is a diagram for describing an outline of data communication via IXP between the two.

FIG. 5 is a diagram for explaining conventional intercommunication of AS via IXP.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 IXP (AS) 12 AS 14 IP router 16 Layer policy addition apparatus 20 Layer policy protection apparatus

Claims (7)

[Claims] 1. A method for connecting a plurality of routing domains via an interconnecting network having an interface formed by an IP layer, wherein two routing control domains that wish to communicate with each other connect to the interconnecting network. Exchanging routing information as an IP layer policy between the two routing domains; and MPLS having information indicating an IP layer policy including at least a routing policy in one of the source routing domains. Generating a label for the packet to be transmitted and extracting the label from the packet in the interconnection network,
Analyzing the IP layer policy indicated in the label; identifying the transfer destination of the packet according to the analyzed IP layer policy; and the other routing domain that is the identified transfer destination of the packet. Routing method to the routing domain. 2. The method according to claim 1, wherein the step of exchanging the route information uses BGP-4.
The interconnection method described in 1. And generating an MPLS label having information indicating an IP layer policy including a policy regarding traffic volume and / or traffic handling,
3. The interconnection method according to claim 1, further comprising a step of adding the packet to a packet to be transmitted. 4. The interconnection method according to claim 1, further comprising the step of counting the number of labeled packets in said interconnection network. 5. An interconnecting device forming an interface by an IP layer as an interconnecting network interposed in data communication of a plurality of routing control domains, wherein routing information from two routing control domains desired to communicate with each other is provided. A routing information transmission processing means for executing a process for transmitting to a routing domain of a communication partner, and an MPLS having information indicating an IP layer policy including a routing policy in one of the transmission source routing domains. It receives a packet to which a label has been added, extracts the label from the packet, and adds the IP to the label.
A layer policy analysis unit for analyzing a layer policy; and a packet transfer destination specified in accordance with the IP layer policy analyzed by the layer policy analysis unit.
An interconnecting device comprising: a packet transfer unit that transfers a packet to another routing domain that is a transfer destination. 6. The apparatus according to claim 1, further comprising packet counting means for counting the number of packets to which the label has been added, wherein the total amount of transmitted and / or received packets is grasped for each of the routing control domains. 6. The interconnect device of claim 5. 7. The interconnection device according to claim 5, wherein the interconnection network also functions as a routing domain.