CN100450063C - Resilient packet ring multi-ring interconnection transmission method based on ring identification routing - Google Patents

Abstract

The multi-ring interconnection transmission method of resilient packet rings based on ring identification routing involves a method for realizing inter-ring packet mutual transmission in a network composed of multiple resilient packet rings (Resilient Packet Ring, RPR) tangentially connected, the method is specifically as follows : 1) It is stipulated that the sub-rings in the multi-ring RPR network are tangentially interconnected, and each RPR sub-ring is assigned a different ring identification number; 2) There are two types of packets transmitted in the multi-ring RPR network: intra-sub-ring 3) For the cross-ring frame, several bytes of variable length are inserted before the header CRC as the "cross-ring control" field defined by the extension, and the current sub-ring where the packet is located The total number of cross-connect nodes is written into the "TTL"field; 4) The first byte of the "cross-ring control" field stores the "cross-ring series", indicating that the packet needs to cross the sub-ring from the current sub-ring to the destination node. The number of rings represents its network lifetime.

Description

Resilient packet ring multi-ring interconnection transmission method based on ring identification routing

technical field

The invention relates to a method for realizing inter-ring packet mutual transmission in a network composed of multiple Resilient Packet Rings (Resilient Packet Ring, RPR) tangentially connected, and belongs to the technical field of communication and information system network transmission.

Background technique

Elastic Packet Ring is a metropolitan area network technology aimed at optimizing the transmission of data packets on the ring topology by adopting a brand-new packet bearer technology. It absorbs the economy of Gigabit Ethernet and the reliability of SDH. The topology of the reciprocal dual optical fiber transmission ring, the outer ring of the two optical fibers clockwise and the inner ring counterclockwise can transmit data or control packets at the same time, so the bandwidth utilization of the network is improved. In addition, new technologies such as space reutilization, automatic protection switching, automatic topology discovery, business graded services, and dynamic allocation of bandwidth resources are used to improve the resource utilization of the ring network.

"IEEE Standards 802.17 Part 17: Resilient packet ring (RPR) accessmethod and physical layer specifications" RPR technical standard was formulated by IEEE802.17WG in September 2004. It is a pure ring (single ring) network transmission, designed to optimize data A new MAC layer protocol proposed for packet transmission. Its application is limited to a single ring, and it cannot realize the end-to-end bandwidth sharing, fair mechanism, QoS and protection functions of cross-ring services. When the number of nodes on the ring increases, the pure ring structure will not be conducive to the improvement of bandwidth utilization. Therefore, in October 2004, IEEE802.17WG issued "IEEE Standards802.17a Media Access Control (MAC) Bridges Amendment 1: Bridging of IEEE802.17" to supplement the previous MAC layer protocol. , bridge the RPR data to other RPR networks or even other IEEE 802 series networks, and realize the cross-ring transmission of data frames through the IEEE 802.1d spanning tree protocol. However, since this type of bridging scheme is addressed by flooding broadcasts between the ring networks, each node needs to copy data frames, which will cause a large load on the network and will also hinder the realization of the advantages of space reuse technology. fully use.

Contents of the invention

Technical problem: The purpose of the present invention is to provide a multi-ring interconnection transmission method based on ring identification routing, which covers the original large-scale RPR ring structure by using multiple small-scale RPR sub-rings for tangential connection The multi-ring RPR network can reduce the scale of the RPR pure ring network, solve the problem that the average allocated bandwidth of the RPR pure ring decreases with the increase of the number of nodes, and can effectively expand the overall number of RPR network nodes, and extend the application of RPR to the wide area network. and access network advancement.

Technical solution: The present invention proposes a multi-ring RPR inter-ring transmission method based on ring identification routing, assigning a definite ring identification number to each sub-ring in the multi-ring network; under the condition of being compatible and supporting the standard RPR packet format, Extended definitions are given to some fields to form a cross-ring transmission frame format. Only the first bit can clearly distinguish the ring and the outer group, and according to the identification number of the sub-ring that needs to be crossed from the source node to the destination node , conveniently realize cross-ring transmission of data, and solve the layer 2 addressing problem between rings in a multi-ring RPR network.

The present invention stipulates that sub-rings in a multi-ring RPR network are tangentially interconnected, and the total number of nodes allowed to be accessed in each sub-ring ring is reduced by half compared with the 255 nodes of the standard RPR, so that the 8 nodes defined in the original standard frame can be used. The most significant bit of the "TTL" field serves as an indication of whether the packet is transmitted across the ring. At the same time, the nodes located at the tangent points in the multi-ring interconnection network are defined as cross-connection nodes, which are responsible for the processing of cross-ring frames and realize cross-ring addressing and transmission. The other nodes are standard nodes, responsible for the processing of RPR standard frames, and completing the transmission and control of standard RPR in the sub-ring. For each node, detecting the first bit of a passed packet can determine whether the packet needs to be transmitted across the ring. If cross-ring transmission is required, each standard node can directly send the packet without any processing. In this way, while reducing the load of each standard node in the ring, the cross-ring transmission performance of packets can also be improved. The present invention describes the route of each packet transmitted between the rings by extending the defined "cross-ring control" field, using the ring identification numbers of each sub-ring that needs to be passed through in the process of arranging the packets in reverse order to reach the destination node, with less overhead The transmission of packets between multiple RPR rings is realized.

The key technology that the present invention realizes is as follows:

(1) It is stipulated that the sub-rings in the multi-ring RPR network are interconnected through tangency. Each RPR sub-ring is assigned a different ring identification number. Considering the rationality of the network scale, the present invention takes the ring identifier as one byte, and allows 255 tangentially interconnected sub-rings. The method of the present invention is also applicable to networks identified by multi-byte rings.

(2) There are two types of packets transmitted in a multi-ring RPR network: packets transmitted within a sub-ring (hereinafter referred to as intra-ring packets) and packets transmitted across rings (hereinafter referred to as cross-ring packets); packets are transmitted in a specified format ( Frame) appears; the cross-ring packet is defined on the basis of the RPR standard frame for compatible expansion, and the first bit is taken as the cross-ring transmission indication XI. XI='0', the frame is a standard frame, used for internal sub-ring transmission; XI='1', indicates that the frame is an extended cross-ring frame, used for cross-ring transmission.

(3) For the extended frame transmitted across the ring, several bytes of variable length are inserted before the header CRC as the "cross-ring control" field defined by the extension. And write the total number of cross-connection nodes in the sub-ring where the group currently resides into the "TTL" field, so as to prevent error frames from forming an infinite loop in the sub-ring. Only the cross-connect node processes the cross-ring frame, so the "cross-ring control" field is inserted into the header of the RPR standard frame to keep the RPR addressing part in the header and has nothing to do with the load. In this way, during the transmission process, each node only needs to process the header and recalculate the CRC of the header without involving the subsequent load part, so the processing time can be significantly shortened.

(4) The first byte of the "cross-ring control" field (see accompanying drawing 4) stores the "cross-ring series", which indicates the number of sub-rings that the packet needs to cross to reach the sub-ring where the destination node is located from the current sub-ring, Represents its network lifetime. The second byte of the "cross-ring control" field starts to address the route for the ring ID whose length changes dynamically, and arranges the ring ID numbers of the sub-rings that the packet needs to pass through in the process of reaching the destination node in reverse order. The purpose of reverse order is to facilitate the step-by-step stripping of the identification numbers of sub-rings that have passed. When the packet reaches the sub-ring where the destination node is located, all the cross-ring control parts of the extended frame will be stripped, and the packet will return to the RPR standard frame format.

On the basis of the above, the specific steps to realize the cross-ring transmission of a packet are as follows:

Step 1: The node receives a packet, first judges whether it is a cross-ring packet according to the frame format of the packet, that is, judges whether the first bit of the packet is "1". If it is "1", and the node is a cross-connect node, then go to the second step; if the node is a standard node, it will not be processed and will be forwarded directly. If it is not "1" and the node is a cross-connect node, it will not be processed and forwarded directly; if the node is a standard node, it will be processed according to the standard RPR method to complete the transmission process.

Step 2: Determine whether the header CRC of the packet is correct, and discard the packet if it is incorrect; if it is correct, further judge whether the "TTL" value is "0", and discard the packet if it is "0"; if it is not "0" , continue to judge whether the "cross-ring series" of the grouping is "0", if it is "0", the grouping is also discarded, if it is not "0", go to the third step.

Step 3: judging whether the ring identification number (one byte before the header CRC) of the currently addressed route is the same as the identification number of the next sub-ring connected to the current node. If they are not the same, subtract one from the "TTL" value, recalculate the header CRC of the packet, and forward the packet in the original transmission direction in the sub-ring where the packet was originally transmitted; if they are the same, go to the fourth step.

Step 4: Strip the ring identification number of the current addressing route (delete this byte), decrease the "cross-ring series" by one, and judge whether the result is "0". If it is not "0", write the total number of cross-connect nodes in the next sub-ring into the "TTL" field, and go to the fifth step; if it is "0", delete the "Cross-ring control" field, and the next The standard topology state database in the sub-ring finds the "TTL" value, fills in the first byte of the packet, and at the same time sets the first bit of the packet to "0" to convert it into the RPR standard frame format, and then go to the fifth step .

Step 5: recalculate the header CRC of the packet, send the packet to the sub-ring tangent to the original transmission sub-ring, and continue the transmission. If the format of the packet has become the RPR standard frame, the transmission can be conveniently completed according to the destination MAC address of the header.

Description of drawings

Figure 1 is a multi-ring RPR network composed of 6 sub-rings tangentially interconnected.

Fig. 2(a) is the standard RPR "ring control" field, and Fig. 2(b) is the "ring control" field proposed by the present invention.

Figure 3 is the extended definition of the RPR cross-ring transmission frame format.

Fig. 4 is a description of the format header of the RPR cross-ring transmission frame addressing the ring identifier.

Fig. 5 is a description of the change of the "cross-ring control" field during the cross-ring transmission process of the RPR addressed by the ring identifier.

Detailed ways

Figure 1 is a multi-ring RPR network composed of 6 sub-rings tangentially interconnected. Each subring has a ring identification number, such as subrings 1, 2, ..., 6 in the figure; nodes connecting two subrings at the same time are cross-connect nodes, as shown in the figure; other nodes are standard RPR nodes.

Fig. 2 (a) is standard RPR " ring control " field, and Fig. 2 (b) is " ring control " field that the present invention proposes, both difference is in " TTL " field, and standard is 8 bits, and the present invention then uses Among them, 7 bits are included, and the highest 1 bit is defined as cross-ring indication XI, and when XI=1, this field is the survival time in the current sub-ring of the cross-ring frame, and its value is the total number of cross-connection nodes in the sub-ring.

Figure 3 is an extended definition of the RPR cross-ring transmission frame format, in which the highest bit of the ring control is "1", and several bytes of variable length are inserted before the header CRC as the "cross-ring control" field. Inserting the "cross-ring control" field into the header can keep the feature that the RPR addressing part is placed in the header and has nothing to do with the load. In this way, during the transmission process, each node only needs to process the header and recalculate the CRC of the header without involving the subsequent load part, so the processing time can be significantly shortened.

Figure 4 is a description of the header of the RPR cross-ring transmission frame format addressed by the ring identifier, and shows the specific form of the cross-ring transmission frame format header when a packet is transmitted from node 6 in sub-ring 5 to node 5 in sub-ring 4 .

Figure 5 is a description of the change of the "cross-ring control" field during the RPR cross-ring transmission process of ring ID addressing. It shows that when a packet is transmitted from node 6 in sub-ring 5 to node 5 in sub-ring 4, the The specific change process of the "ring control" field.

The present invention stipulates that a multi-ring RPR network is composed of multiple tangentially interconnected sub-rings, as shown in FIG. 1 . The nodes on each RPR ring are divided into standard nodes and cross-connect nodes. The standard node can implement ring-up, ring-down, forwarding, and discarding of data frames, while the cross-connect node does not generate data frames, but only completes the forwarding and discarding operations of data frames. The cross-connect node may include two MAC modules, which belong to two tangent sub-rings and are connected back-to-back, so as to realize data exchange inside the node. In the process of automatic topology discovery in a multi-ring network, the two MAC modules of each cross-connect node first complete the topology discovery of the standard RPR in their respective rings, generate a standard topology state database in the ring, and then participate in cross-ring automatic topology discovery . The cross-ring automatic topology discovery mechanism is mainly to help establish the ring identification route transmitted between multiple rings. During this process, the two MAC modules in the cross-connect node respectively record the topology status of all reachable network parts in the direction of the ring to which they belong, and realize information sharing among each other, realizing network globalization with less overhead Topological information collection.

The present invention compresses the single-ring scale of the RPR ring network, and the number of nodes in each RPR sub-ring does not exceed 128. Therefore, the highest bit of the 8-bit "TTL" field defined in the original standard frame is also the highest bit of the entire packet. The bit is always '0', but the hardware executes as '0' by default. The present invention then utilizes this bit as the indication XI of grouping whether cross-ring transmission (XI='0' represents that this frame does not need to cross-ring transmission, and XI='1' represents that the destination node of this frame is not in this ring), to ring and Packets transmitted across the ring are clearly distinguished in the first bit of each packet. Therefore, for each node, the first bit of each packet passed on it indicates whether the destination node of the packet is in the ring, if the bit is '1', each ordinary node can no longer do any processing on the packet , direct direct transmission, so that while reducing the load of each common node in the ring, the transmission performance of the packet can also be improved. For other addressing-related information, several bytes are inserted before the "header CRC" field of the standard RPR frame, which is defined as the "cross-ring control" field for description. Apparently, since the first bit of the extended cross-ring frame is indicated, common nodes only need to simply forward, and only cross-connect nodes process the "cross-ring control" field. Therefore, the frame format of the packets transmitted between the rings maintains compatibility with the RPR standard frame.

Figure 2 (a) and (b) show the definitions of the standard RPR "ring control" field and the "ring control" field proposed in this paper, respectively. The difference between the two is in the "TTL" field, the standard is 8 bits, and the present invention uses 7 bits, and the highest 1 bit is extended and defined as the cross-ring indication XI, and when XI=1, this field is the cross-ring frame sub In-ring survival time, its value is the total number of cross-connect nodes in the sub-ring. Every time a cross-connection node is passed, the survival time in the sub-ring of the cross-ring frame is reduced by one. When the "TTL" field of the received cross-ring frame is zero, it is discarded, thus avoiding the formation of an "infinite loop" of error frames in the sub-ring.

The present invention uses an 8-bit field to describe the identification number of the ring, and such a definition can realize the interconnection of 255 RPR rings (the identification number "0" is reserved, and there is no tangent ring indication at one end of the cross-connection node). The route of data transmission across rings is described by the MAC address of the source node, the ring identification number that crosses the rings on the way, the ring identification number of the destination node, and the MAC address of the destination node. The description of the route is given in the "cross-ring control" field. out. The "cross-ring control" field in the RPR cross-ring transmission packet based on ring identifier addressing is defined as follows: the first byte is used as the "cross-ring series" indication, which is used to describe the ring that the frame needs to cross when it is transmitted from the current ring to the target ring of series. The "Ring Identification Route" field of m bytes thereafter is used to describe the ring identification numbers of all the rings that the frame needs to pass through from the ring where the source node is located to the ring where the destination node is transmitted in reverse order (as shown in Figure 3). In this way, after the cross-ring frame enters a new ring, the cross-ring series number is reduced by 1. When the cross-ring series number is reduced to 0, but the destination node has not yet been reached, the frame is deemed invalid and discarded.

Whenever a cross-ring frame enters a new sub-ring, the entry cross-connect node should remove its header field and regenerate the header field, where the updated fields are "ring control", "cross-ring series", "ring identification Routing" and "Header CRC" fields. It can be seen that adding the "cross-ring control" field before the header CRC, updating the header field only needs to recalculate the header CRC, without processing the subsequent payload, thus greatly reducing the processing load of each node, which is more conducive to Improve the transmission performance of the ring network.

For example, in the multi-ring RPR network composed of 6 sub-rings tangentially interconnected as shown in Figure 1, a certain packet needs to be transmitted from node 6 in sub-ring 5 to node 5 in sub-ring 4, the frame format header of the packet is As shown in Figure 4. Wherein, XI=1, TTL=2, according to the hexadecimal format, the destination MAC address is 00-10-A4-97-A8-DE, and the source MAC address is 00-10-A4-96-A8-AF; Its ring identification route is (sub-ring 5) → (sub-ring 1) → (sub-ring 2) → (sub-ring 4), that is, the entire packet needs to cross 3 rings, so "cross-ring series = 3, the The change of the "cross-ring control" field during packet transmission is shown in Figure 5. When the packet is in sub-ring 5, the "cross-ring series" is 3, which is offset backward by the "cross-ring series" field 3. Obtain the ring identification number of the next target ring of the grouping as '1'. And the routing of the grouping in the sub-ring 5 is (node 6)→(node 5)→(node 4). When the grouping arrives at node 5 When , because it is a cross-connect node, it will process the packet header. First, the TTL will be reduced by one, and then the ring identification number of the next target ring will be found. Compared with the tangent ring identification number connected to itself, the result is not the same, so go to node 4. Node 4 also subtracts one from the TTL first, then finds the ring ID of the next target ring, compares it with the ID of the tangent ring it is connected to, and the result is the same, so it transfers the packet to sub-ring 1 to continue transmission. The ring identification number of the next destination ring is wrong, and the comparison result of node 4 is also different. The packet continues to be transmitted in sub-ring 5, and passes through nodes 3, 2, 1, and 6. These nodes are all standard nodes and are not processed. Cross-ring grouping, so the grouping returns to node 5. Node 5 finds that the TTL value has been "0", so it discards the grouping, avoiding its infinite loop in the sub-ring. If the routing of the grouping in the sub-ring 5 is (Node 6)→(Node 1)→(Node 2)→(Node 3)→(Node 4), since nodes 6, 1, 2, and 3 are all standard nodes, they do not process cross-ring packets, so the packets arrive quickly Node 4. Therefore, any node in sub-ring 5 can determine that the packet should leave the ring from node 4.

Before the packet leaves the ring at node 4, the "cross-ring series" at the header of the packet should be reduced by one, and the ring identification number 1 should be deleted, and then forwarded to node 1 of sub-ring 1. Node 1 of sub-ring 1 and node 4 of sub-ring 5 are two back-to-back connected MACs in the same cross-connect node. When the packet is transferred to node 1 of subring 1, it only needs to write the total number of cross-connect nodes 2 of subring 1 into the "TTL" field, and determine the forwarding route of the packet in subring 1 (inner ring or outer ring) , in this example, the paths on both sides are equal, so the forwarding direction will be determined according to the bandwidth utilization. Then the packet can be forwarded to node 4 of sub-ring 1 for processing. At this time, the "cross-ring progression" is 2, and the next target ring identification number of the packet obtained by offset 2 is 2. In this way, the packet can reach the sub-ring 4 where the target node is located. In node 3 of sub-ring 4, set XI=0, clear the "cross-ring control" field, and at the same time, according to the destination MAC address, determine RI=0, TTL=1, the frame format of the packet is exactly the same as that of the standard RPR, and finally it is passed smoothly sent to the destination node.

Claims (1)

1. Resilient Packet Ring multiple ring interconnection transmission method based on ring sign route is characterized in that this method is as follows:

1.) between the subrings in the many rings of the regulation RPR networks by tangent interconnection, different ring identification number of each RPR subring distribution; Consider the reasonability of network size, get ring and be designated a byte, the subring number that allows tangent interconnection is 255, defining the node that is positioned in the multiple ring interconnection network on the points of tangency simultaneously is cross connection node, be responsible for the processing of the transannular frame of expansion, realize transannular addressing and transmission, other node is a standard nodes, be responsible for the processing of RPR standard frame, finish transmission and the control of subring internal standard RPR;

2.) grouping of transmitting in many ring RPR networks has two classes: the grouping of the grouping of transmission and transannular transmission in the subring; Format frame with regulation during transmitted in packets occurs; Being grouped in of transannular transmission carried out the compatible extensions definition on the RPR standard frame basis, get its first bit as transannular transmission indication XI, when XI=' 0 ', this frame is a standard frame, is used to transmit the grouping of transmission in the subring; When XI=' 1 ', this frame is the transannular frame of expansion, is used to transmit the grouping of transannular transmission;

3.) transannular frame to expanding, before stem CRC, insert adjustable length some bytes, as " transannular control " field of expanded definition, and the cross connection node sum in the current place subring of will dividing into groups writes " TTL " field, prevents that erroneous frame from forming endless loop in subring; Have only cross connection node just to handle the transannular frame of expansion, " transannular control " field is inserted the transannular frame stem of RPR expansion, partly place stem, with the irrelevant characteristics of load to keep the RPR addressing; In transmission course, each node only need be handled stem like this, recomputates the CRC of stem, to shorten the processing time;

4.) " transannular control " first byte of field is deposited " transannular progression ", indicates grouping and arrives the subring number that destination node place subring need stride across by the subring of current place, represents its network lifetime; Second byte of " transannular control " field begins the ring sign route for the length dynamic change, and inverted order discharging grouping arrives the ring identification number that needs each subring of process in the destination node process; The purpose of inverted order is for the ease of peeling off the identification number of the subring of having passed through step by step, and when grouping arrives the subring of destination node place, the transannular control section of the transannular frame of expansion will all be stripped from, and packet recovery is the RPR standard frame format;

The transannular transmission concrete steps that realize a grouping are as follows:

The first step: node is received a grouping, judges that at first whether this grouping is the grouping of transannular transmission, promptly judges according to the frame format of grouping whether first bit of this grouping is " 1 "; Be " 1 ", and node is cross connection node, then changed for second step over to, node is a standard nodes, does not then deal with, directly forwarding; Be not " 1 ", and node is cross connection node, then do not deal with that directly transmit, node is a standard nodes, then handles according to standard RPR method, finishes transmission course;

Second step: whether the stem CRC that judges grouping is correct, if incorrectly then abandon this grouping; If correct, judge further whether " TTL " value is " 0 ", if " 0 " also abandons this grouping; Not being " 0 ", judging further whether " the transannular progression " of grouping is " 0 ", if " 0 " also abandons this grouping, is not " 0 ", changes for the 3rd step over to;

The 3rd step: the ring identification number of judging current addressing route, the identification number that is the next subring that whether connects with this node of the byte in stem CRC front is identical, if it is inequality, " TTL " value is subtracted one, recomputate the stem CRC of grouping, in the subring of the former transmission of grouping, transmit grouping by former transmission direction; If identical, then changed for the 4th step over to;

The 4th step: peel off the ring identification number of current addressing route, promptly delete this byte, simultaneously " transannular progression " is subtracted one, and whether judged result is " 0 "; If be not " 0 ", the cross connection node sum in the next subring is write " TTL " field, changed for the 5th step over to; If " 0 " then deletes " transannular control " field, and checks in " TTL " value by the standard topology slip condition database in next subring, insert first byte of grouping, the first bit reset of will dividing into groups simultaneously makes it be transformed into the RPR standard frame format, changes for the 5th step then over to;

The 5th step: recomputate the stem CRC of grouping, the next subring that by this node be connected tangent with former transmission subring sent in grouping, continue to transmit; If grouping has become the RPR standard frame, then, can finish transmission easily according to the target MAC (Media Access Control) address of its stem.

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