KR102416153B1 - System for highly available service function chaining on programmmable switches - Google Patents

Abstract

A service function chaining system according to an embodiment of the present invention forms a plurality of service chains between a client and a server, and in the service function chaining system including a programmable switch that is monitored and controlled by a controller, the controller is one service chain When a line failure is detected in the service function chaining packet processing process through the will be.

Description

SYSTEM FOR HIGHLY AVAILABLE SERVICE FUNCTION CHAINING ON PROGRAMMMABLE SWITCHES

The present invention relates to a service function chaining system, and more particularly, a high-availability service function that enables seamless packet transmission and reception even in the event of a network failure when processing packets through service function chaining in a network switch device equipped with a programmable switch ASIC It relates to the chaining system.

Service function chaining has attracted much attention by enabling complex in-network packet processing in which packets are processed by sequentially visiting service functions (SFs) specified in the service chain. are receiving

The service function chaining packet is controlled by chaining functions (CF) such as service function classifier (SC) and service function forwarder (SFF). Here, the service function classifier (SC) encapsulates and decapsulates the packet at both ends of the network so that the packet can start and end service function chaining, and the service function forwarder (SFF) determines that the arriving packet is visited next It is responsible for determining and delivering the service function (SF) to be performed. In addition, the service function (SF) performs various functions such as firewall and NAT for packets.

As in-network packet processing is network intensive, low latency and high throughput must be provided. However, since the chaining function (CF) and the service function (SF) usually operate on a general-purpose server, it is difficult to satisfy these requirements. In addition, since the chaining function (CF) and the service function (SF) are physically separated, in order to process a packet, a delay time of several hundred microseconds must be experienced. Today's switch hardware only requires processing delay of less than 1 microsecond per packet, so the delay that occurs through the chaining function (CF) and service function (SF) is a factor that greatly increases the overall delay of the service function chaining (SFC). it works In addition, commercial servers provide lower packet-per-second throughput compared to switch hardware.

Meanwhile, programmable switch ASICs such as the recently emerged Barefoot Tofino allow users to reconfigure the packet processing pipeline. Accordingly, an approach to achieve low latency and high throughput by implementing the chaining function (CF) and service function (SF), which are components of service function chaining, on a programmable switch has been proposed.

It is an object of the present invention to enable service function chaining to operate normally without interruption even when a network failure occurs on a programmable switch supporting high availability. (SF), and when a network failure such as a circuit failure occurs as the switches are merged into one node, the service function chaining is also not processed normally. An object of the present invention is to provide a service function chaining system that solves the above problems by monitoring the line state and updating the service chain information of the service function classifier (SC) when a failure occurs so that the service function chaining packet is transmitted to an alternative service chain.

A service function chaining system according to an embodiment of the present invention for solving the above problems forms a plurality of service chains between a client and a server, and in a service function chaining system comprising a programmable switch monitored and controlled by a controller, When a line failure is detected in the process of processing a service function chaining packet through one service chain, the controller updates the route to an alternative service chain without a line failure so that the service function chaining packet is transferred and processed to the corresponding alternative service chain.

Here, the service chain includes: a service function classifier module connected to a client and responsible for encapsulation; It is connected to the service function classifier module and may include a first service function module in charge of a service function (SF) and a second service function module in charge of a service function (SF) and decapsulation.

In addition, the controller records initial service chain information in the service function classifier module and each service function module at the time of initial operation. The packet forwarding path can be updated by writing to the child module.

In addition, when the port of each service function module is detected, the controller reads the $DEV_PORT value corresponding to the port index number in the programmable switch with reference to the Barefoot Runtime API provided by the programmable switch, and the $DEV_PORT value corresponds to Down It is possible to judge a line failure depending on whether the value is

In addition, the service function chaining packet includes a service chain header (SCH) and a service function header (SFH) for service function chaining between an Ethernet (ETH) header and an IP header, and the service chain header includes a service chain identifier an ID field and a LEN field for counting the number of service function modules passed through so far in reverse order, wherein the service function header includes an SF field for recording an identifier of a service function module to be visited by the service function chaining packet; a TAIL field indicating the position of the SF field, and the ingress parser of the programmable switch indicates the last position of the TAIL field value in the process of parsing from the Ethernet (ETH) header to the IP header Parsing can be repeated until

In addition, the service function chaining packet processing may be performed when the programmable switch checks the value of the Type of Service (ToS) field in the IP header and confirms that the service function chaining packet is a service function chaining packet.

In addition, in the process of processing the service function chaining packet, if it is confirmed that the service function chaining packet is the service chain header, the existence of the service chain header is checked. can be processed after generating in the packet.

Also, the existence of the service chain header can be checked by verifying the validity through the isvalid() function.

In addition, in the service function chaining packet processing, the LEN field value is decreased by 1 whenever service chaining packet processing is received through the service function module, and the SF field-TAIL field pair at the front of the service function header is removed. The process may be repeated until the LEN field value becomes 0.

In addition, the controller reads the service chain information stored in the service function chaining packet upon initial operation and stores a service function chaining forwarding rule that forwards the packet to a corresponding output port, and the service function chaining packet processing is performed in the LEN field If the value is not 0, it goes to SF Forward to perform the SFF function, and the output port of the current packet can be determined by referring to the service function chaining forwarding rule stored in the programmable switch.

In the service function chaining system according to an embodiment of the present invention, as the chaining function (CF) and service function (SF), which existed as separate nodes on the network, and the switch are merged into one node, a network failure such as a line failure occurs In the case where the service function chaining is also not handled normally, the service chain information is stored in the packet header rather than each switch, and the controller monitors the switch line status to update the service chain information of the service function classifier (SC) when a failure occurs. This allows service function chaining packets to be transmitted to an alternative service chain so that service function chaining can operate normally without interruption even in the event of a network failure on a programmable switch supporting high availability.

In addition, the above-mentioned effects according to the embodiments of the present invention are not limited to the described content, and may further include all effects predictable from the specification and drawings.

1 is a block diagram of a network using service function chaining using a programmable switch according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an operation process of a controller located in a control plane among the networks shown in FIG. 1 .
3 schematically illustrates the structure of a service function chaining packet header according to an embodiment of the present invention.
4 is a diagram schematically illustrating a process of parsing a packet header in a programmable switch according to an embodiment of the present invention.
5 is a schematic diagram of an ingress pipeline for processing a packet in a programmable switch according to an embodiment of the present invention.
6 is a diagram illustrating a change in a packet header during service function chaining according to an embodiment of the present invention.
7 is a diagram illustrating a process in which a controller responds to a network failure during service function chaining using the service function chaining system according to an embodiment of the present invention.

Hereinafter, the description of the present invention with reference to the drawings is not limited to specific embodiments, and various modifications may be made and various embodiments may be provided. In addition, it should be understood that the contents described below include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention.

In the following description, terms such as 1st, 2nd, etc. are terms used to describe various components, meanings are not limited thereto, and are used only for the purpose of distinguishing one component from other components.

Like reference numbers used throughout this specification refer to like elements.

As used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise. In addition, terms such as "comprises", "comprises" or "have" described below are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist. It should be construed as not precluding the possibility of addition or existence of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

In addition, terms such as "unit", "unit", and "module" described in the specification mean a unit that processes at least one function or operation, which is implemented by hardware or software or a combination of hardware and software can be

Hereinafter, a service function chaining system on a programmable switch supporting high availability according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a network using service function chaining using a programmable switch according to an embodiment of the present invention. Referring to FIG. 1 , the service function chaining system of the present invention can be used in a network 10 including a control plane 100 and a data plane 200 . In addition, the control plane 100 may be configured to include the controller 110 . In this case, the controller 110 may monitor and control the programmable switches 230 existing in the data plane 200 .

The data plane 200 may include a client 210 , a server 220 , and a programmable switch 230 . At this time, the programmable switch 230 may be formed to take charge of all service function classifier (SC), service function forwarder (SFF), and service function (SF) required for service function chaining. have.

To this end, in the network 10 according to an embodiment of the present invention, for example, a total of four programmable switches 230 may exist, and serve as a service function classifier (SC) among the four programmable switches 230 and perform encapsulation. The service function classifier module 231 in charge may be connected to the client 210 .

In addition, a plurality of first service function modules 232 and a plurality of second service function modules 233 may exist between the client 210 and the server 220 , and the service function classifier module 231 and the first and Since all of the second service function modules 233 may perform the role of the service function forwarder (SFF), the service function forwarder module is not separately provided.

Here, the plurality of first service function modules 232 located in the middle are responsible for only the service function (SF), and the second service function module 233 located at the end is a service function classifier together with the service function (SF). Among the roles of (SC), it may also perform the function of decapsulation.

In this case, it is preferable that the plurality of first service function modules 232 have different nodes. This is to cope with a line failure, and when a line through one first service function module 232 fails, a connection node is changed to another first service function module 232 .

That is, a service function chaining packet (hereinafter referred to as a 'packet') is transmitted and processed through the programmable switch 230 between the client 210 and the server 220. In the embodiment of the present invention, the service function classifier The module 231, the first service function module 232, and the second service function module 233 are sequentially passed through. Since a plurality of the first service function modules 232 are provided to form different nodes, Even if a line failure occurs, it may be possible to change the route.

Here, the service function classifier module 231 , the first service function module 232 , and the second service function module 233 are the above-described service function classifier (SC), service function forwarder (Service Function Forwarder), SFF) and the service function (SF) form the programmable switch 230 that can take charge of both, hereinafter, the sum of these will be referred to as a service chain.

That is, the service function chaining system according to the embodiment of the present invention is a service chain (SRC) composed of the sum of the service function classifier module 231 , the first service function module 232 , and the second service function module 233 . It is provided in plurality between the client 210 and the server 220 .

On the other hand, the programmable switch 230 as described above is limited to four as shown in the drawings to help the understanding of the present invention, but this is only an example and is not limited, and the number of programmable switches 230 is formed differently than that can be

For example, another service function module may be provided between the first service function module 232 and the second service function module 233 .

FIG. 2 is a flowchart illustrating an operation process of a controller located in a control plane among the networks shown in FIG. 1 .

Referring to FIG. 2 , when the controller 110 is initially driven, the service function classifier module 231 that is each programmable switch 230 present in the network 10 and each service function module 232 , 233 have an initial service chain. Information can be recorded to enable packet transmission and reception through service function chaining.

In this case, the controller 110 may store the service function module to be passed through each service chain (SRC) and the order thereof in the service function classifier module 231 responsible for encapsulation.

In addition, the controller 110 reads the service chain information stored in the packet header so that the packet processed by the service function module itself can perform a service function forwarder (SFF) function that allows the service function module to visit the next service function module. A service function chaining forwarding rule for forwarding packets to an output port may be stored.

As described above, when the writing of the initial service chain information is finished, the controller 110 waits for 1 second, which is for the controller 110 to monitor the port information of the programmable switch 230 every second. In this case, 1 second is a desirable number designated by the network user, and is not necessarily limited thereto, and may be changed to an arbitrary value that is less than 1 second or exceeds 1 second.

In addition, the controller 110 may read the port state of each service function module (232, 233) when the one-second standby is finished. This process can be performed by reading the $DEV-PORT value corresponding to the port index number in the programmable switch 230 with reference to the Barefoot Runtime API provided by the programmable switch 230 .

Here, if the $DEV_PORT value read by the controller 110 is not a value corresponding to Down, the controller 110 waits again for 1 second through the process of “No” and then reads the port status of each service function module 232 and 233. The action can be repeated.

On the other hand, if the value of $DEV_PORT is a value corresponding to Down, through a process of “YES”, the controller 110 transmits the replacement service chain information of service chains (SRCs) passing through the corresponding service function module to the service function classifier module 231 ) so that a packet newly entering the network 10 does not pass through the service function module in which the failure has occurred any longer.

Thereafter, the controller 110 waits again for 1 second and repeats the following processes until it is forcibly terminated by the user.

3 schematically illustrates the structure of a service function chaining packet header according to an embodiment of the present invention.

Referring to FIG. 3 , a service function chaining packet header according to an embodiment of the present invention may include two headers for service function chaining supporting high availability between an Ethernet (ETH) header and an IP header.

The first is a service chain header (SCH), which may include an ID field, which is a service chain (SRC) identifier, and a LEN field, which counts the number of service functions (SFs) that have been passed so far in reverse order.

The second is a service function header (SFH). The service function header may include an SF field that records the identifier of a service function module to be visited by the packet, and a TAIL field that indicates the location of the SF field. . That is, the SF field may indicate that the corresponding service function module is the last of the corresponding service chain (SRC). Here, the maximum length n of the service chain (SRC) may be adjusted by a user's setting, and the service function header may be composed of a pair of n SF fields and TALI fields.

4 is a diagram schematically illustrating a process of parsing a packet header in a programmable switch according to an embodiment of the present invention.

Referring to FIG. 4 , when a packet is received at an input port, the ingress parser of the programmable switch 230 may start reading service chain information in the packet header from the Ethernet (ETH) header.

Here, the ingress parser parses the service chain header (SCH) and then parses the service function header (SFH). In this case, the parsing process checks the value of the TAIL field among the subheaders of the service function header (SFH), and the corresponding value If this value is 1, after parsing the IP header, the entire parsing process can be terminated.

On the other hand, if the TAIL field value is 0, it means that there are still more subheaders to be parsed, so the parsing of the service function header may be repeated until a subheader having a TAIL field value of 1 is met.

5 is a schematic diagram of an ingress pipeline for processing a packet in a programmable switch according to an embodiment of the present invention.

Referring to FIG. 5 , when packet processing starts, the programmable switch 230 reads the Type of Service (ToS) field value in the IP header to check whether it is 0 or more. Here, the default value of the ToS field is 0, which means it is not a service function chaining packet, and when the ToS field is 1 or more, it means a service function chaining packet. Also, in this case, the ToS field can serve as an index number of the service chain.

Therefore, if the value of the ToS field is 0, Ethernet or IP packet forwarding may be immediately performed and the packet processing process may be terminated. On the other hand, if the value of the ToS field is 1 or more, the next step may be performed.

For a packet having a ToS field value of 1 or more, the programmable switch 230 may verify the validity of a service function header (SCH) through the isvalid( ) function. Here, the presence of the service function header (SCH) means that the current encapsulation of this packet is completed.

That is, when the answer to the isvalid() function is “No”, encapsulation is performed to add a service chain header (SCH) and a service function header (SFH) to the packet, and then processing can be received.

If the service chain header (SCH) exists or encapsulation is completed, the programmable switch 230 may perform SF processing for the corresponding packet. In this case, the service function SF may be performed according to a process set by the user in the corresponding programmable switch 230 , such as NAT and firewall.

If the user does not set the service function SF in the corresponding programmable switch 230, the packet may pass through the service function module to which the service function SF is not set without going through a processing process.

After receiving the service function (SF) processing, the programmable switch 230 decreases the LEN field value of the service chain header (SCH) by 1, and pops the SF-TAIL pair, which is the first subheader of the service function header (SFH). It can be removed through the -front() function. Here, the initial value of the LEN field is the length of the service chain. The above process indicates that the current packet has received normal service function (SF) processing via the service function module specified by the service chain (SRC).

Thereafter, the programmable switch 230 may check whether the value of the LEN field of the service chain header SCH is 0. A LEN field value of 0 means that the current packet has visited all service functions (SFs) specified in the service chain. Therefore, in this case, through the process of “YES”, the programmable switch 230 removes the service chain header (SCH) and the service function header (SFH) by performing decapsulation of the corresponding packet, and then the ETH/IP packet You can perform forwarding and end packet processing. If the value of the LEN field is not 0, the next step, “NO”, goes through to SF Forward.

SF Forward may perform the function of a service function forwarder (SFF). Specifically, the output port of the current packet may be determined by referring to the service function chaining forwarding rule stored by the programmable switch 230 . Here, the key value of the service function chaining forwarding rule is the ID of the service function module, and the returned value is the output port number. After being processed by such SF Forward, the processing of the corresponding packet may be completed.

Hereinafter, a change in a packet header during service function chaining using the service function chaining system of the present invention and a process in which the controller responds to a network failure will be described through the following examples.

The following examples are only a process for explaining the present invention in more detail, and the content of the present invention is not necessarily limited to the following examples.

[Embodiment 1] Change of packet header during service function chaining using the service function chaining system of the present invention

6 is a diagram illustrating a change in a packet header during service function chaining according to an embodiment of the present invention.

In this embodiment, only the case of passing through four service function modules is considered regardless of the network environment described with reference to FIG. 1 .

When a service function chaining packet first enters the network 10, the service function classifier module 231 performs encapsulation and inserts a service chain header (SCH) and a service function header (SFH) into the existing packet header. Thereafter, the LEN field value of the service chain header SCH is decreased by 1 every time the service function module is passed through, and the SF-Tail field pair located at the front of the service function header SFH is sequentially removed.

Immediately after receiving the last service function (SF) process from the second service function module 233 , the service function header (SFH) no longer exists in the packet, and only the service chain header (SCH) having the LEN field value of 0 remains. . At this time, the programmable switch 230 performs de-encapsulation to remove the service chain header (SCH) and then sends out the packet.

[Embodiment 2] Process in which the controller responds to a network failure in service function chaining using the service function chaining system of the present invention

7 is a diagram illustrating a process in which a controller responds to a network failure during service function chaining using the service function chaining system according to an embodiment of the present invention.

In this embodiment, the existing service chain (SRC1) is the first service function module 232a of SF1 - the second service function module 233 of SF3, and the replacement service chain (SRC2) is the first service function module 232a of SF2 - It is set as the second service function module 233 of SF3. In addition, a case where the maximum length of the service chain (SRC) is 4 was considered. In addition, the value of the ToS field of the service function chaining packets sent by the client 210 to the server 220 is used as 1. That is, the client 210 uses the service chain ID 1 .

When a packet arrives at the service function classifier module 231 of SC1, the service function classifier module 231 of SC1 performs encapsulation with reference to the service chain information it stores as shown in ①. . Thereafter, the packet is transmitted to the first service function module 232a of SF1 through SF Forward.

The first service function module 232a of SF1 transmits the packet after processing the service function (SF) to the second service function module 233 of SF3. However, as shown in ②, a line failure occurs between the first service function module 232a of SF1 and the second service function module 233 of SF3, so that the packet of the first service function module 232a of SF1 is transmitted to the second service of SF3. It is not transmitted to the function module 233 .

At this time, the controller 110 of this embodiment detects such a network failure and replaces the basic service chain (SRC1) information of the service chain ID 1 stored in the service function classifier module 231 of SC1 as shown in ③ into the replacement service chain ( SRC2) information is updated.

Accordingly, the packets using the subsequent service chain ID 1 are no longer the first service function module 232 of SF1 - the second service function module 233 of SF3, but the first service function module 232b of SF2 as shown in ④. )- is transmitted to the server 220 via the path of the second service function module 233 of SF3.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can practice the present invention in other specific forms without changing the technical spirit or essential features of the present invention. you will be able to understand Accordingly, the embodiments described above are illustrative in all respects and not restrictive.

10: network
100: control plane
110: controller
200: data plane
210: client
220 : server
230: programmable switch
231: service function classifier module
232: first service function module
233: second service function module
SRC: Service Chain

Claims (10)

A service function chaining system comprising a programmable switch that forms a plurality of service chains between a client and a server and is monitored and controlled by a controller,
The controller is
When a line failure is detected during service function chaining packet processing through one service chain, the route is updated to an alternative service chain without line failure so that the service function chaining packet is delivered and processed to the alternative service chain;
The service chain is
a service function classifier module that is connected to the client and is responsible for encapsulation;
A first service function module connected to the service function classifier module and in charge of a service function (SF); and
Includes a second service function module responsible for service function (SF) and decapsulation (Decapsulation),
The controller is
Initial service chain information is recorded in the service function classifier module and each service function module at the time of initial operation. update the forwarding path;
The controller is
When the port of each service function module is detected, the $DEV_PORT value corresponding to the port index number in the programmable switch is read with reference to the Barefoot Runtime API provided by the programmable switch, and the $DEV_PORT value is A service function chaining system, characterized in that determining a line failure.
delete delete delete The method of claim 1,
The service function chaining packet is
a service chain header (SCH) and a service function header (SFH) for service function chaining between the Ethernet (ETH) header and the IP header;
The service chain header is
It includes an ID field, which is a service chain identifier, and a LEN field, which counts the number of service function modules that have been passed so far in reverse order,
The service function header is
The service function chaining packet includes an SF field for recording the identifier of the service function module to be visited, and a TAIL field for indicating the location of the SF field,
In the process of parsing from the Ethernet (ETH) header to the IP header, the ingress parser of the programmable switch repeats parsing until the TAIL field value indicates the last position. system.
6. The method of claim 5,
The service function chaining packet processing is,
The service function chaining system, characterized in that the programmable switch checks the value of the Type of Service (ToS) field in the IP header, and performs processing when it is confirmed that the packet is a service function chaining packet.
7. The method of claim 6,
In the process of processing the service function chaining packet,
When the service function chaining packet is confirmed, the existence of the service chain header is checked. If there is no service chain header, encapsulation is performed to generate the service chain header and the service function header in the packet, and then processing is performed. service function chaining system.
8. The method of claim 7,
The service function chaining system, characterized in that the presence or absence of the service chain header is verified by validating the isvalid() function.
7. The method of claim 6,
The service function chaining packet processing is,
Each time the service chaining packet is processed through the service function module, the LEN field value is decremented by 1 and the process of removing the SF field-TAIL field pair at the front of the service function header is performed when the LEN field value becomes 0. Service function chaining system, characterized in that it is repeatedly performed until
10. The method of claim 9,
The controller is
At the time of initial operation, the service function chaining forwarding rule for reading the service chain information stored in the service function chaining packet and forwarding the packet to the corresponding output port is stored;
The service function chaining packet processing is,
When the LEN field value is not 0, the service function chaining function moves to SF Forward to perform the SFF function, and determines the output port of the current packet by referring to the service function chaining forwarding rule stored in the programmable switch. system.

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