CN113489642A

CN113489642A - PIM-SM source registration optimization method

Info

Publication number: CN113489642A
Application number: CN202110754030.1A
Authority: CN
Inventors: 蒲涛
Original assignee: Xinhe Semiconductor Technology Wuxi Co Ltd
Current assignee: Xinhe Semiconductor Technology Wuxi Co Ltd
Priority date: 2021-07-04
Filing date: 2021-07-04
Publication date: 2021-10-08
Anticipated expiration: 2041-07-04
Also published as: CN113489642B

Abstract

The invention discloses a PIM-SM source registration optimization method, the registration forwarding tree creation process is as follows: when the S-DR receives multicast data from a multicast source, no multicast forwarding table item exists at the moment, the multicast data is uploaded to a protocol layer for registration and encapsulation, and unicast is sent to the RP; when the S-DR sends the registration message, monitoring a sending port, creating a temporary forwarding table entry T (S, G), wherein the forwarding port is the sending port of the registration message; the intermediate router monitors the forwarding of the registration message, and also creates a temporary forwarding table entry T (S, G), wherein the forwarding port is the forwarding port of the registration message. The invention has the advantages that the establishment of the registration multicast tree is rapid and efficient, the time for continuously sending the registration message is reduced, and the registration processing burden of the S-DR is lightened; the registration messages from each S-DR are reduced, thereby greatly relieving the processing burden of the RP and optimizing the performance bottleneck point of the whole multicast system.

Description

PIM-SM source registration optimization method

Technical Field

The invention relates to the technical field of multicast routing, in particular to a PIM-SM source registration optimization method.

Background

PIM-SM is a multicast routing technique commonly used in large networks. The method and the device carry out the forwarding of the multicast data according to the requirement of the multicast receiving end. According to the protocol standard, the creation of PIM-SM multicast forwarding path is divided into the following three main stages:

the first stage is as follows: creation of the RPT. For creating a shared forwarding tree RPT from the multicast rendezvous point RP to the receiver.

As shown in FIG. 1, S-DR is a multicast designated router on the multicast source side, and R-DR1 and R-DR2 are multicast designated routers on the receiver side. The receiver 1 and the receiver 2 apply for joining a specific multicast group to the designated routers R-DR1 and R-DR2 through IGMP protocol, trigger the R-DR1 and R-DR2 to initiate the (G) Join message to the RP, and create the (G) forwarding table entry along the way, thereby forming a multicast forwarding path tree from the RP to the R-DR, which is called a sharing tree RPT. After the multicast data reaches the RP, the multicast data is forwarded to R-DR1 and R-DR2 through RPT and finally reaches receiver 1 and receiver 2.

And a second stage: and (4) registering the multicast source. For creating a multicast forwarding path from a multicast source to an RP, called a multicast source tree.

As shown in fig. 2, when the S-DR receives multicast data sent by a multicast source, it triggers a multicast registration source process, and firstly encapsulates the original multicast data into a registration message by the S-DR, unicast-forwards the registration message to the RP, and after receiving the registration message, the RP sends an (S, G) Join message to the S-DR, creates an (S, G) multicast forwarding table along the path, where the forwarding port is a receiving port of the (S, G) Join message, and finally forms a multicast forwarding path from the S-DR to the RP, which is called a multicast source tree. In the process, the S-DR continuously registers and encapsulates the received multicast data and sends the multicast data to the multicast rendezvous point RP in a unicast mode.

And (4) multicasting the source tree, wherein the S-DR continuously sends the registration message, and simultaneously copies the original data and forwards the original data to the RP through the multicasting source tree. And after receiving the original multicast data, the RP sends a registration stop message to the S-DR and stops sending the registration message. So far, the subsequent multicast data is completely forwarded to the RP through the multicast source tree. Finally, the shared tree RPT multicast created by the first stage is forwarded to the receiver.

And a third stage: and (6) switching the STP. For creating the shortest forwarding path from the multicast source to the R-DR, reducing unnecessary detours through the RP.

As shown in FIG. 3, when the original multicast data reaches R-DR, it can initiate (S, G) Join message to Source according to the trigger condition, so as to create the shortest multicast forwarding path from Source to R-DR, called SPT. And the switching from the RPT to the SPT forwarding path is referred to as SPT switching. Taking fig. 3 as an example, the shortest path tree path from the multicast source to the receiver 1 is: multicast source- > S-DR- > R-DR1- > receiver 1.

In the above process, especially in the second stage of registration process, the hardware cannot automatically encapsulate the registration message, and the registration message needs to be uploaded to the protocol layer for software encapsulation. If too many messages need to be registered and encapsulated, a great processing burden is caused to the S-DR and the SP, thereby affecting the performance of the whole multicast system.

As can be seen from the timing diagram of the anchor registration mechanism shown in fig. 4, the registration process starts from the first multicast data trigger until the S-DR receives a registration stop message from the RP. The sending of the registration message is stopped after 4 message interaction (namely, the interaction of the registration message, (S, G) Join message, the original multicast data and the registration stop message) processes between the S-DR and the RP. The interaction times are many, software layer interaction is mostly achieved, the processing time is long and unstable, a large amount of registration messages are easily packaged and sent to the RP for a long time, the processing overhead of S-DR registration packaging is increased, and meanwhile, the processing burden of the RP on the de-packaging of the registration messages is increased. For the RP, it will face the registration messages from multiple S-DRs, and at the same time, it will also participate in other process processing of the multicast routing, which is a performance bottleneck point in the multicast system, and the excessive registration messages will undoubtedly make the processing burden more severe, thereby affecting the stability of the whole multicast system.

To avoid the above problems, the currently commonly adopted solution is:

1. and the number of the registration messages is reduced on the S-DR side to relieve the burden of the S-DR and the RP.

2. The reception of registration messages is restricted at the RP to reduce processing burden.

However, in any of the above methods, the overall forwarding performance is mitigated at the cost of reducing the forwarding rate by discarding the multicast data. The processing burden of the multicast data cannot be reduced while the multicast data is forwarded as much as possible, and the multicast forwarding performance of the whole system is improved.

Disclosure of Invention

The invention aims to provide a PIM-SM source registration optimization method, which reduces the processing load of S-DR and RP on registration messages while providing the maximum multicast forwarding efficiency, and optimizes the performance of the whole multicast system so as to solve the problems provided in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

PIM-SM source registration optimization method, through monitoring and utilizing unicast registration message forwarding path to quickly create temporary multicast forwarding path tree, so as to forward original multicast data as early as possible through the forwarding tree, and reduce the original message to be registered, packaged and forwarded as early as possible; the temporary multicast forwarding tree is created according to the forwarding of the registration message, and is called as a registration forwarding tree.

The creation process of the registration forwarding tree is as follows:

when the S-DR receives multicast data from a multicast source, no multicast forwarding table item exists at the moment, the multicast data is uploaded to a protocol layer for registration and encapsulation, and unicast is sent to the RP; when the S-DR sends the registration message, monitoring a sending port, creating a temporary forwarding table entry T (S, G), wherein the forwarding port is the sending port of the registration message;

in addition, the Router in the middle monitors the forwarding of the registration message, and also creates a temporary forwarding table entry T (S, G), wherein the forwarding port is the forwarding port of the registration message; thus, a multicast forwarding path from the S-DR to the RP, i.e., a registration forwarding tree, is formed.

Because the forwarding path of the registration forwarding tree is consistent with the forwarding path of the registration message, the registration message is guaranteed to reach the midway router before the original multicast message, and the midway router can guarantee that the T (S, G) table entry on the router has been issued before the original data is forwarded through software and hardware means, so that the original multicast data is forwarded according to the table entry, and finally the RP is reached.

The optimized forwarding flow is as follows:

after the S-DR establishes the T (S, G) table entry, the subsequent multicast message is directly multicast-forwarded through the table entry without registration, encapsulation and transmission; the time T from the transmission of the first registration message to the transmission of the T (S, G) table entry is shorter, so that the number of the registration messages generated by the existing logic is smaller;

the RP follows the standard processing logic to process the registration message and the original multicast data, and triggers the (S, G) Join and the registration stop message of the S-DR; (S, G) Join takes a receiving port as a forwarding port along the way to create (S, G) table items, and finally forms a multicast source path tree from the S-DR to the RP; at this moment, the (S, G) list item is used as a later multicast forwarding list item, and T (S, G) is not effective any more, so that the switching from the multicast registration tree to the multicast source tree is completed, and the standard processing flow is returned to, and the standard multicast source registration behavior is compatible;

in order to avoid accidental loss of the registration message and periodic refreshing of T (S, G) table entries, when the S-DR finishes issuing the T (S, G) table entries until the time T2 from the time when the registration stop message is received, a certain amount of original messages are periodically copied, registered and sent, and the frequency N can be configured; periodic fixed low frequency registrations do not place a processing burden on the system.

The present invention requires revising the processing logic on the S-DR and intermediate routers, the specific processing of which is described below.

(I) S-DR Process flow

The main difference of the S-DR relative to the standard PIM-SM processing flow lies in:

a learning process of newly adding T (S, G) temporary table items;

(S, G) Join message processing and updating (S, G) table entries;

periodic copying register packages.

The T (S, G) learning process of S-DR is as follows:

(1) when the S-DR receives the multicast data from the multicast source, the multicast data is uploaded to a CPU for registration and encapsulation because the forwarding rule of the multicast group is not established;

(2) after the registration message is packaged, the registration message is sent to the RP through unicast;

(3) the S-DR monitors the forwarding of the registration message and acquires a forwarding port as a forwarding port of T (S, G);

(4) the S-DR establishes a T (S, G) table entry according to the information, and the multicast forwarding port is a port for sending the registration message;

(5) after creating T (S, G) list item, the multicast data is directly transmitted according to the T (S, G) list item, and the registration and encapsulation are not carried out by uploading software.

In addition, in the subsequent monitoring of the registration message, if the sending port is changed, the table entry of T (S, G) is updated.

(S, G) Join processing and (S, G) entry update

According to the standard definition of PIM-SM, when S-DR receives (S, G) Join message from RP, creating (S, G) table entry, besides registering message, copying original multicast message to make multicast forwarding according to (S, G) table entry. At this time, the continuous registration message is already stopped sending when the T (S, G) entry is created, and the original multicast stream is also forwarded when the T (S, G) entry is created. Therefore, at this time, the newly created (S, G) entry is only needed to be used as the forwarding table, and the T (S, G) entry is no longer valid, thereby completing the switching from the temporarily generated registration tree forwarding path to the forwarding path of the multicast source tree.

3. Periodic copy registration encapsulation

The RP cannot be reached, and the registration message forwarding path may change, taking into account the loss of the registration message. After the T (S, G) table entry is created, until the S-DR receives the registration stop message, that is, within the time range of T2 in fig. 7, the S-DR configures a fixed sampling and encapsulation frequency according to the situation of the entire system, for example, within an interval range of every second, 3 original messages are sampled, and the S-DR sends the protocol layer to perform registration encapsulation, so as to maintain the forwarding table entry of the registration forwarding tree between RPs.

(II) processing by intermediate routers

In the technical scheme of the invention, the learning of the register forwarding tree and the maintenance of the final multicast source tree item by the intermediate router are introduced, and the main revision processing part is as follows:

newly adding a learning process and maintenance of a T (S, G) temporary table entry;

and (S, G) updating and maintaining the forwarding table entry.

T (S, G) entry learning and maintenance

The T (S, G) learning process of the intermediate router is as follows:

(1) the registration message from the S-DR will precede the original multicast data;

(2) the router monitors the forwarding of the registration message, and the invention is not limited to hardware or software monitoring and learning;

(3) the router learns a forwarding port of the registration message, and creates a T (S, G) table entry, wherein the forwarding port is the forwarding port of the registration message;

(4) and forwarding the subsequent multicast data according to the T (S, G) table entry.

In addition, the continuous registration message snooping is used for updating the T (S, G) table entry in time.

Update and maintenance of (S, G) forwarding entries

Like the processing of S-DR, the intermediate router performs (S, G) table item learning according to the Join message of RP according to the standard definition of PIM-SM, and the forwarding port is the receiving port of the (S, G) Join message; the (S, G) table item is used as a forwarding table item of subsequent original multicast data, and the previous T (S, G) table item is not effective any more, so that the switching to the multicast source tree is completed.

Compared with the prior art, the invention has the advantages that:

1. the establishment of the registration multicast tree is fast and efficient, the time for continuously sending the registration message is reduced, and the registration processing burden of the S-DR is lightened;

2. the registration messages from each S-DR are reduced, so that the processing load of the RP is greatly relieved, and the performance bottleneck point of the whole multicast system is optimized;

3. the registered multicast tree is the same as the forwarding table entry of the multicast source tree, hardware implementation is facilitated, linear speed multicast forwarding can be rapidly achieved under the condition of hardware support, a large amount of packet loss caused by software registration is reduced, and multicast data forwarding efficiency is improved.

Drawings

Fig. 1 is a schematic diagram of shared tree RPT creation.

Fig. 2 is a schematic diagram of multicast source tree creation.

Fig. 3 is a shortest path tree switching diagram.

FIG. 4 is a timing diagram of a multicast registration mechanism

FIG. 5 is a flow chart of the registration forwarding tree creation of the present invention

Fig. 6 is a schematic structural diagram of a registered forwarding path tree according to the present invention.

Fig. 7 is a forwarding flow chart after optimization according to the present invention.

FIG. 8 is a flowchart of the learning of T (S, G) of the S-DR in the present invention.

Fig. 9 is a flow chart of T (S, G) learning of the intermediate router in the present invention.

Fig. 10 is a diagram illustrating duration of a registration message according to a conventional scheme.

Fig. 11 is a graph of registration message duration using a registration forwarding tree in accordance with the present invention.

Detailed Description

The technical solution of the present patent will be described in further detail with reference to the following embodiments.

In the embodiment, a temporary multicast forwarding path tree is quickly created by monitoring and utilizing a unicast registration message forwarding path, so that original multicast data is forwarded through the forwarding tree as early as possible, and registration, encapsulation and forwarding of the original message are reduced as early as possible; the temporary multicast forwarding tree is created according to the forwarding of the registration message, and is called as a registration forwarding tree.

Firstly, the creating process of the registration forwarding tree is as follows:

as shown in fig. 5, when the S-DR receives multicast data from a multicast source, there is no multicast forwarding entry at this time, the multicast data is sent to a protocol layer for registration and encapsulation, and unicast is sent to the RP; when the S-DR sends the registration message, monitoring a sending port, creating a temporary forwarding table entry T (S, G), wherein the forwarding port is the sending port of the registration message;

in addition, the Router in the middle monitors the forwarding of the registration message, and also creates a temporary forwarding table entry T (S, G), wherein the forwarding port is the forwarding port of the registration message; thus, a multicast forwarding path from the S-DR to the RP, i.e., a registered forwarding tree, is formed, as shown in FIG. 6.

Secondly, the optimized forwarding process is as follows:

as shown in fig. 7, after the S-DR has created the T (S, G) entry, the subsequent multicast packet is multicast-forwarded directly through the entry without performing registration encapsulation transmission; the time T from the transmission of the first registration message to the transmission of the T (S, G) table entry is shorter, so that the number of the registration messages generated by the existing logic is smaller;

(I) S-DR Process flow

a learning process of newly adding T (S, G) temporary table items;

(S, G) Join message processing and updating (S, G) table entries;

periodic copying register packages.

1. As shown in FIG. 8, the T (S, G) learning process of S-DR is as follows:

(S, G) Join processing and (S, G) entry update

3. Periodic copy registration encapsulation

(II) processing by intermediate routers

and (S, G) updating and maintaining the forwarding table entry.

T (S, G) entry learning and maintenance

As shown in fig. 9, the T (S, G) learning flow of the intermediate router is as follows:

Update and maintenance of (S, G) forwarding entries

In this embodiment, the duration of the conventional registration packet and the duration of the registration packet using the registration forwarding tree of the present invention are compared and analyzed:

fig. 10 illustrates the duration of a registration message in a conventional scheme, which is to continuously register and encapsulate multicast data from a multicast source to an RP within a time t. T-T1 + T2+ T3+ T4+ T5+ T6+ T7.

Wherein T1, T3, T5 and T7 are transmission times of the interactive message, and are assumed to be a fixed time Tt. And T2, T4, and T6 are software processing times of each message processing logic, and are assumed to be a fixed time Ts for comparison and analysis.

Then the duration of the registration message is t4 Tt +3 Ts.

The registration message time chart after using the present invention is shown in fig. 11, where the continuous registration message time is T1-T1, T1 is the monitoring and learning processing time of the registration message, and is also assumed to be Ts, then T1-Ts.

And the sending time T2 of the periodic sampling registration message is T2+ T3+ T4 is 2 Tt + Ts. But the periodic sampling registration frequency is adjustable, and continuous registration messages can not be generated to stress the system, so the influence can be ignored and is not remembered

In conclusion, compared with the long-time continuous registration process of the traditional scheme, the method and the device for realizing the multicast service of the multicast system greatly shorten the continuous registration time, thereby greatly reducing the registration messages in the multicast system and further improving the overall performance of the multicast system.

Although the preferred embodiments of the present patent have been described in detail, the present patent is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present patent within the knowledge of those skilled in the art.

Claims

PIM-SM source registration optimization method, which is used for rapidly creating a temporary multicast forwarding path tree, namely a registration forwarding tree, by monitoring and utilizing unicast registration message forwarding paths, and is characterized in that the creation process of the registration forwarding tree is as follows: when the S-DR receives multicast data from a multicast source, no multicast forwarding table item exists at the moment, the multicast data is uploaded to a protocol layer for registration and encapsulation, and unicast is sent to the RP; when the S-DR sends the registration message, monitoring a sending port, creating a temporary forwarding table entry T (S, G), wherein the forwarding port is the sending port of the registration message; the Router in the middle monitors the forwarding of the registration message, and also creates a temporary forwarding table entry T (S, G), wherein the forwarding port is the forwarding port of the registration message.
2. The PIM-SM source registration optimization method of claim 1, wherein the S-DR differs from the standard PIM-SM process flow mainly in that:

a learning process of newly adding T (S, G) temporary table items;

(S, G) Join message processing and updating (S, G) table entries;

periodic copying register packages.
3. The PIM-SM source registration optimization method of claim 1, wherein the learning of the registration forwarding tree and the maintenance of the final multicast source tree entry by the intermediate router are introduced, and the main revision processing part is as follows:

newly adding a learning process and maintenance of a T (S, G) temporary table entry;

and (S, G) updating and maintaining the forwarding table entry.
4. The PIM-SM source registration optimization method of claim 2, wherein the T (S, G) learning procedure of S-DR is as follows:

(1) when the S-DR receives the multicast data from the multicast source, the multicast data is uploaded to a CPU for registration and encapsulation because the forwarding rule of the multicast group is not established;

(2) after the registration message is packaged, the registration message is sent to the RP through unicast;

(3) the S-DR monitors the forwarding of the registration message and acquires a forwarding port as a forwarding port of T (S, G);

(4) the S-DR establishes a T (S, G) table entry according to the information, and the multicast forwarding port is a port for sending the registration message;

(5) after creating T (S, G) list item, the multicast data is directly transmitted according to the T (S, G) list item, and the registration and encapsulation are not carried out by uploading software.
5. The PIM-SM source registration optimization method of claim 2, wherein the RP processes the registration packet and the original multicast data following the standard processing logic, and when the S-DR receives the (S, G) Join message from the RP, creates an (S, G) entry, and the original multicast packet copies a copy of the packet for multicast forwarding according to the (S, G) entry in addition to the registration packet; at this time, the continuous registration message is already stopped sending when the T (S, G) table entry is created, and the original multicast stream is forwarded when the T (S, G) table entry is created; at this time, the newly created (S, G) entry is only needed to be used as the forwarding table, and the T (S, G) entry is no longer valid, so that the switching from the temporarily generated registration tree forwarding path to the forwarding path of the multicast source tree is completed.
6. The PIM-SM source registration optimization method of claim 2, characterized in that after T (S, G) table entry creation, until S-DR receives a registration stop message toPeriodic registration message transmission timeIn the time range of t2, S-DR configures a fixed sampling envelope according to the condition of the whole systemThe periodic fixed low frequency registration does not impose processing burden on the system.
7. The PIM-SM source registration optimization method of claim 3, wherein the T (S, G) learning process of the intermediate router is as follows:

(1) the registration message from the S-DR will precede the original multicast data;

(2) the router monitors the forwarding of the registration message, and the invention is not limited to hardware or software monitoring and learning;

(3) the router learns a forwarding port of the registration message, and creates a T (S, G) table entry, wherein the forwarding port is the forwarding port of the registration message;

(4) and forwarding the subsequent multicast data according to the T (S, G) table entry.
8. The PIM-SM source registration optimization method of claim 3, wherein the intermediate router performs (S, G) table entry learning according to Join messages of RP according to the standard definition of PIM-SM, and the forwarding port is a receiving port of the (S, G) Join messages; the (S, G) table item is used as a forwarding table item of subsequent original multicast data, and the previous T (S, G) table item is not effective any more, so that the switching to the multicast source tree is completed.