KR100981567B1 - Method to Guarantee End-to-End QoS in PPP and HDLC Circuit Emulation over MPLS - Google Patents

Abstract

The present invention relates to a method of delivering QoS information when a PPP / HDLC virtual circuit service is provided in an MPLS network. And sending the HDLC frame / Cisco_HDLC frame to a service provider border router associated with the subscriber router.

Description

Method to Guarantee End-to-End QoS in PPP and HDLC Circuit Emulation over MPLS using PPC and HDLC Virtual Line Services using MPLs

1 illustrates a PPP-over-MPLS network element in accordance with the present invention.

2 illustrates how PPP is encapsulated.

3 illustrates how QoS information is matched to an HDLC frame.

4 illustrates packet forwarding status from a customer edge router to a provider edge router with QoS information.

The present invention provides QoS information of a subscriber to an MPLS network in order to guarantee quality of service (QoS) in Point-to-Point Protocol (PPP) -over-Multi Protocol Label Switching (MPLS) line emulation or HDLC-over-MPLS emulation. It relates to a method for delivery.

Due to the universalization of the Internet, various services exist on the network, QoS technologies are being developed to differentiate between these various services, and networks that want to provide QoS are gradually increasing. In general, to provide QoS, the packet is identified by the source address / destination address of the IP header, the destination port number, or the EXP bit of the MPLS header. do.

In addition to the proliferation of Internet traffic, a link with a large capacity is required. A widely used for large-capacity purposes is POS (Packet Over Synchronous Optical Network (SONET) / Synchronous Digital Hierarchy (SDH). POS is more expensive than Giga Ethernet, but it is often used because of its low overhead and ease of long-distance transmission. POS can use several methods in Layer 2, but mainly uses two methods to carry IP. One is to use PPP and the other is to use Cisco High-Level Data Link Control (HDLC). The method using PPP uses HDLC as Layer 2 layer and uses PPP protocol between IP layer and Layer 2 layer. The method using Cisco-HDLC carries an IP layer in a Cisco-HDLC frame without using a PPP protocol.

POS was developed mainly for the direct link between routers, and was developed based on the assumption that it was physically connected directly. Therefore, it did not consider carrying QoS information. In the case of a direct connection, each router removes the POS frame header and reads the IP header or the MPLS header so that QoS can be performed using the information in the IP header or the MPLS header. However, when virtually reproducing an end-to-end PPP or HDLC over MPLS connection using MPLS between distant routers, there is a problem that the QoS information of the packet cannot be recognized in the intermediate network. This is because the intermediate network does not read the headers of the packets in the POS frame, but only adds new headers.

In order to solve the problems of the related art, the present invention aims to ensure QoS in MPLS networks by delivering QoS information to MPLS networks when providing virtual line services using PPP or Cisco-HDLC in MPLS networks. do.

The two-layer protocol used in POS is HDLC or Cisco-HDLC. The difference between HDLC and Cisco-HDLC is that Cisco-HDLC has an identifier that distinguishes what kind of data is in the information area. The HDLC frame consists of address, control, information and FCS fields. The control field is intended for flow control on the original data link. However, as the performance of the equipment is excellent, the error rate on the link is greatly reduced and the speed is very high, the high speed router uses little of the flow control using the control field of the HDLC. An object of the present invention is to transmit QoS information of three layers to the second layer by using a control field which is not used as described above, so that the QoS information of the subscriber is transmitted to the MPLS network.

Both PPP and Cisco-HDLC use existing HDLC frames. Therefore, both schemes include address, control, and FCS fields inside the frame. However, as described above, Cisco-HDLC is different in that an identifier for data included in an information area is included. In case of using PPP, PID field of PPP is used as identifier. Therefore, PPP or Cisco-HDLC use substantially the same frame structure.

If QoS is normally provided in an MPLS network, QoS can be provided end-to-end even in PPP or Cisco-HDLC virtual circuit service. By using this technology, QoS can be provided while taking advantage of the virtual line service in the MPLS network.

The present invention relates to a method for delivering QoS information when a PPP virtual circuit service is provided in an MPLS network, comprising: mapping, at a subscriber router, QoS information extracted from a subscriber packet to a control field of an HDLC frame; and mapping an HDLC frame to a subscriber. Transmitting to a service provider border router associated with the router.

The present invention also relates to a method for delivering QoS information when providing HDLC virtual circuit service in an MPLS network, comprising: mapping, at a subscriber router, QoS information extracted from a subscriber packet to a control field of a Cisco-HDLC frame; and Sending the HDLC frame to a service provider border router associated with the subscriber router.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

1 is a diagram illustrating a method of emulating a remote PPP connection by PPP-over-MPLS. A PPP-over-MPLS connection requires a Customer Edge Router (1-1) and a Provider Edge Router (1-2) that connects with the Subscriber Router (1-1) at the edge of the MPLS network. do. The service provider boundary routers 1-2 create a virtual line through a label distribution protocol (LDP). Service Provider Routers 1-3 do not require any special functionality other than MPLS. The MPLS network 1-4 is responsible for forwarding packets by MPLS label switching between the service provider border router 1-2 and the service provider border router 1-2.

In this environment, a virtual line is created between the service provider border router 1-2 and the service provider border router 1-2. The types of virtual lines may be classified into various types according to what kind of link the service provider border router 1-2 and the subscriber router 1-1 are connected through. In this embodiment, the service provider border router 1 2) and the subscriber router 1-1 are connected through a POS link, and the data link layer uses a virtual circuit using HDLC or Cisco-HDLC.

2 illustrates the structure of a PPP packet, the structure of an HDLC frame, and the structure of a Cisco-HDLC frame. The PPP packet is largely composed of protocol (2-31), information (2-32), and padding (2-33). The protocol 2-31 identifies what kind of higher level protocol is carried in the PPP packet, and the information 2-32 is the data carried in the actual PPP. The PPP packet has an integer multiple of 4 bytes, and the padding 2-33 adjusts the integer multiple of 4 bytes. These PPP packets are piled up again in HDLC frames and transmitted between the two devices.                     

The HDLC frame consists of headers 2-1, 2-2, data 2-3, and FCS 2-4. The header of the HDLC consists of an address 2-1 and a control 2-2. The address represents the other party's address or full address (broadcast address, etc.), and the control 2-2 is used for flow control. However, as the link speeds up and HDLC is frequently used in a point-to-point manner, the address (2-1) and control (2-2) areas are used differently from their original purpose. In particular, as the link speeds up and the error rate is significantly reduced, the flow control function is rarely used.

The Cisco-HDLC Frame The Cisco-HDLC Frame contains the Address 2-10, Control 2-20, Format 2-30, Data 2-40, and FCS 2-50 fields. The other fields except the format (2-30) field are the same as the HDLC frame. As described above, the format (2-30) field indicates the type of data stored in the data (2-40) field.

3 is a configuration diagram illustrating a method of delivering QoS information using an HDLC frame structure and an HDLC frame. The control field 3-2 of the HDLC frame is rarely used as described above. Therefore, the QoS information can be transmitted to the MPLS network 1-4 using this. The control field 3-2 of the HDLC frame consists of a total of 1 byte (8 bits) and uses this to convey QoS information. 3 shows an embodiment in which three bits (3-21) of the control field 3-2 are used for QoS delivery.

4, a preferred embodiment of the present invention will be described. In the embodiment of FIG. 4, the subscriber router 4-1 and the service provider's edge router 4-2 are connected by using a POS line, and the service provider is PPP-over- using the MPLS network 4-4. We want to provide MPLS or HDLC-over-MPLS circuit emulation service. In addition, the service provider's MPLS network already provides QoS, and the subscriber network also provides QoS.

Since the subscriber network already provides QoS, the subscriber's packet contains QoS information. This QoS information may be in the header of the IP packet, and may exist in the MPLS header if the subscriber side is already operating the MPLS network. The subscriber router 4-1 may classify each field by combining various fields of the IP header. In order to deliver QoS information of each packet to the service provider's network, the subscriber router 4-1 records the QoS information of each packet in a control field of an HDLC frame (Cisco-HDLC frame in HDLC over MPLS emulation). To pass. In addition, the service provider's edge router 4-2 classifies the packet by service based on the QoS information of the control field of the HDLC frame transmitted from the subscriber router 4-1 (Cisco-HDLC frame in HDLC over MPLS emulation). Re-mark to MPLS EXP according to QoS policy of subscriber network and deliver.

This enables end-to-end QoS delivery between subscribers in PPP or HDLC over MPLS circuit emulation. QoS policy between subscriber and service provider is made by service level agreement (SLA) of both sides.

Although the emulation of the circuit using MPLS reduces the actual utilization of the link due to packet overhead, the subscribers need to exchange routing information with the service provider because the subscribers appear to be connected to the network end-to-end. none. This reduces the load on the equipment and makes it very easy to operate. This is very effective in terms of security since one subscriber's IP address is not exposed to another.

Through the present invention, QoS information is transparently transmitted between the subscriber and the service provider, thereby guaranteeing end-to-end QoS during circuit emulation of the PPP and HDLC in the MPLS network through the POS line. In this way, subscriber-to-end QoS can be guaranteed to provide a more complete virtual circuit service.

Claims (8)

In providing PPP virtual circuit service in MPLS network Mapping, at the subscriber router, QoS information extracted from the subscriber packet to a control field of the HDLC frame; And Transmitting the HDLC frame to a service provider border router associated with the subscriber router QoS information delivery method comprising a. The method of claim 1, Mapping, at the service provider border router, the QoS information mapped to the control field of the HDLC frame to a QoS information area of a service provider network. In providing HDLC virtual circuit service in MPLS network, Mapping, at the subscriber router, QoS information extracted from the subscriber packet to a control field of a Cisco-HDLC frame; And Transmitting the Cisco-HDLC frame to a service provider border router associated with the subscriber router QoS information delivery method comprising a. The method of claim 3, wherein Mapping, at the service provider border router, the QoS information mapped to the control field of the Cisco-HDLC frame to a QoS information area of a service provider network. In providing a PPP virtual circuit service in an MPLS network, Mapping QoS information of the service provider network to the control field of the HDLC frame at the service provider border router; And Transmitting the HDLC frame to a subscriber router connected to the service provider border router QoS information delivery method comprising a. The method of claim 5, And mapping the QoS information mapped to the transmitted HDLC frame control field to the QoS information area of a subscriber network at the subscriber router. In providing HDLC virtual circuit service in MPLS network, Mapping, at the service provider edge router, QoS information of the service provider network to a control field of a Cisco-HDLC frame; And Transmitting the Cisco-HDLC frame to a subscriber router connected to the service provider border router QoS information delivery method comprising a. The method of claim 7, wherein Mapping the QoS information mapped to the transmitted Cisco-HDLC frame control field to the QoS information area of a subscriber network at the subscriber router;

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