CN115484202B

CN115484202B - INT-based lightweight path detection method

Info

Publication number: CN115484202B
Application number: CN202211013069.9A
Authority: CN
Inventors: 郭永安; 田丰; 王禹博; 佘昊; 钱琪杰
Original assignee: Nanjing University of Posts and Telecommunications
Current assignee: Nanjing University of Posts and Telecommunications
Priority date: 2022-08-23
Filing date: 2022-08-23
Publication date: 2023-05-30
Anticipated expiration: 2042-08-23
Also published as: CN115484202A

Abstract

The invention discloses a light path detection method based on INT, which comprises the following steps: the INT source terminal encapsulates the telemetry header into an ith data packet containing INIT signals, and the data packet is sequentially forwarded through a switch on a transmission link until reaching an INT receiving terminal; when the (i+1) th data packet from the same data stream arrives at the INT source end, when the INT source end detects that the data packet does not contain any telemetry header, the INT source end packages the telemetry header into the (i+1) th data packet, inserts an ID and sends the ID to a next hop switch; the next-hop switch forwards the received (i+1) th data packet to the next-hop switch until the INT receiving terminal is reached; the INT receiving terminal extracts the telemetry probe from the data packet and sends the telemetry value to the telemetry server. The invention reduces the transmission cost of INT under the condition of ensuring the monitoring precision; and processing management information for the merged data stream, so that the resource occupation and processing complexity of each node are greatly reduced.

Description

INT-based lightweight path detection method

Technical Field

The invention relates to the technical field of computer networks, in particular to a light path detection method based on INT.

Background

With the rapid development of the information age, network monitoring requirements with higher accuracy and correctness are put forward for 5G and 6G network services, so that the application degree of network faults or congestion can be detected as early as possible, and the network faults or congestion can be processed in time, so that the smoothness of the network is ensured.

In-band telemetry (INT) is a new network monitoring method, and conventional in-band network telemetry may generate a large amount of telemetry data, which not only occupies network bandwidth, but also aggravates server data collection, storage and analysis burden; all traffic forwarded by all nodes of the network is telemetered in an in-band network, one node adds telemetry data of tens of bytes for each data packet, the data packet accumulates a large amount of trace data in the whole forwarding path, and the accumulated trace data may even exceed the size of the original data packet to generate additional transmission overhead, so that the link utilization rate is reduced, the data completion time is delayed, the processing burden of the switch is increased, and the network transmission speed is reduced.

Disclosure of Invention

The invention aims to: in view of the above problems, an object of the present invention is to provide a lightweight path detection method based on INT.

The technical scheme is as follows: the invention discloses a light path detection method based on INT, which comprises the following steps:

the INT source terminal encapsulates the telemetry header into an ith data packet containing INIT signals, and the data packet is sequentially forwarded through a switch on a transmission link until reaching an INT receiving terminal;

each exchanger on the transmission link changes the current telemetry state into a preparation insertion ID according to the INIT signal carried in the received ith data packet;

when the (i+1) th data packet from the same data stream arrives at the INT source end, when the INT source end detects that the data packet does not contain any telemetry header, the INT source end packages the telemetry header into the (i+1) th data packet, inserts an ID and sends the ID to a next hop switch;

the next-hop switch forwards the received (i+1) th data packet to the next-hop switch until the INT receiving terminal is reached;

the INT receiving terminal extracts the telemetry probe from the data packet and sends the telemetry value to the telemetry server.

Further, all switch states on the transmission link are set to wait for initialization before the INT source encapsulates the telemetry header into the ith data packet containing the INIT signal.

Further, after the INT source encapsulates the telemetry header into the (i+1) th data packet and inserts the ID step, the telemetry status of the INT source is changed from ready to insert ID to inserted ID.

Further, when the (i+2) th data packet from the same data stream reaches the INT source end, the INT source end forwards the data packet to the next hop switch, the switch in the state of being ready for inserting the ID inserts the ID in the telemetry header, and encapsulates the ID in the (i+2) th data packet, the state is updated to be the inserted ID, and the data packets are sequentially forwarded through the switch until reaching the INT receiving terminal.

Further, after the path detection of the same data stream is completed, all switches on the transmission link are in the state of having inserted an ID, the INT receiving terminal sends out a reset signal, the reset signal is reversely forwarded to the INT source end, the telemetry state of all switches is reset to wait for initialization, and the path detection is repeatedly executed.

The beneficial effects are that: compared with the prior art, the invention has the remarkable advantages that:

1. the invention aims to reduce the transmission overhead of INT under the condition of ensuring the monitoring precision; the management information is processed on the merged data stream without packet-by-packet processing, so that the resource occupation and the processing complexity of each node are greatly reduced;

2. in order to reduce the state quantity required to be maintained for each switch, a group of telemetry states maintained in the P4 programmable switch are defined, which is helpful for the switch to coordinate and aggregate telemetry values distributed in a plurality of data packets; for telemetry status lookup and update, using bloom filters to compress the status tables in the P4 programmable switch greatly optimizes space efficiency and query time.

Drawings

FIG. 1 is a block diagram of a path detection implementation;

fig. 2 is a path detection flow chart.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples.

As shown in fig. 1, the lightweight path detection method based on INT according to the present embodiment of the present invention includes the following steps:

All switch states on the transmission link are set to wait for initialization before the INT source encapsulates the telemetry header into the ith data packet containing the INIT signal.

After the INT source encapsulates the telemetry header into the (i+1) th data packet and inserts the ID step, the telemetry status of the INT source changes from ready to insert ID to inserted ID.

When the (i+2) th data packet from the same data stream reaches the INT source end, the INT source end forwards the data packet to the next hop switch, the switch in the state of being ready for inserting ID inserts ID into the telemetry header, and encapsulates the ID into the (i+2) th data packet, the state is updated to be the inserted ID, and the data packets are sequentially forwarded through the switch until reaching the INT receiving terminal.

When the path detection of the same data stream is completed, all switches on the transmission link are in the state of being inserted with ID, the INT receiving terminal sends out a reset signal, the reset signal is reversely transmitted to the INT source end by the path, the telemetry state of all switches is reset to be waiting for initialization, and the path detection is repeatedly executed.

In order to more clearly show the implementation process of the light path detection method based on INT, the following transmission link is used for explanation, 5P 4 programmable switches are arranged in the transmission link for transmitting data packets, and the specific structure is as shown in fig. 1 and 2, switch s1 is used as an INT source end, switch s5 is used as an INT receiving terminal, switches s2, s3 and s4 are used as INT forwarding devices, and the INT receiving terminal is connected with a telemetry server.

Three telemetry states are defined, respectively, wait for initialization (when the switch is waiting for an initialization signal to insert its ID), prepare for inserting an ID (when the switch is ready to insert its ID and telemetry information into the corresponding data packet of the data stream), and insert an ID (when the switch has inserted its own ID and waits for the signal to return to the original state for reinsertion of its ID). Three telemetry states are maintained and updated in each P4 programmable switch using bloom filters, compressing the state tables in the P4 switches, greatly optimizing space efficiency and query time.

The bloom filter workflow is:

(1) Bloom filter initialization: any data has not been placed in the bloom filter, and the values of all bits are 0, indicating telemetry status awaiting initialization;

(2) Bloom filter lookup: for each incoming data packet, by computing m hash functions H of a predefined header field (e.g., five-tuple) ₁ ()，...H _m () To identify the state of the data stream to which the data packet belongs. The state of the data stream is identified by computing values in the bloom filter, i.e., m hash function re-modulo operations on predefined header fields.

(3) Bloom filter update: the value of the search position of the bloom filter and three telemetry states establish a mapping relation: i.e. 0 for waiting for initialization, 1 for ready insertion of an ID, and 2 for inserted ID.

INT-based lightweight path detection method with 5 switches, wherein bloom filters in all switches are set to wait for initialization state, data packets are received from switch s1, and the insertion sequence of telemetry values is carried out according to the following steps:

step 1, the switch s1 is used as the INT source end of the data stream, encapsulates the telemetry header into a data packet containing the INIT signal to trigger the switch on the subsequent transmission link to insert the telemetry value, and when the data packet is transmitted on the transmission link, each switch on the transmission link receives the INIT signal, and the INIT signal changes the telemetry status of the current switch from waiting for initialization to preparing for inserting an ID.

Step 2, when the next packet from the same data stream arrives at switch s1 (when switch s1 is in a ready-to-insert ID state), switch s1 detects that the packet does not contain any telemetry header. Switch s1 encapsulates the telemetry header into a data packet and inserts its own ID. Meanwhile, the telemetry status of switch s1 changes to an inserted ID. After receiving the data packet containing the telemetry header, the subsequent switch on the transmission link only forwards the data packet without performing an ID insertion operation. The last switch s5 on the transmission link is the INT receiving terminal, extracts the telemetry header from the data packet and sends the telemetry value to the telemetry server.

Step 3, when the next packet arrives at switch s1, switch s1 directly forwards the packet without inserting any telemetry value because s1 is in the inserted ID state. Subsequently, the switch s2 in the state of being ready to insert an ID performs the same operation as s1 in the previous step, i.e., inserts its ID in the telemetry header and is encapsulated in a data packet. Next, the state of s2 is updated to the inserted ID.

Step 4, similar to the rule of the previous step, the switch s3 and the switch s4 perform telemetry information insertion and forward data packets.

And 5, when the next data packet of the transmission link arrives, the switches s1 to s4 are in an inserted ID state, and as the switch s5 serves as an INT receiving terminal, a telemetry header is not required to be inserted into the datagram, the switch s5 matches the telemetry header, extracts all telemetry information and sends all telemetry information to a telemetry server, and path detection of a specific data stream is completed.

Step 6, the path detection of the specific data stream is performed only once so far, and all switches on the transmission link are in the state of having inserted the ID, meaning that the telemetry value is not inserted into other data packets belonging to the same data stream. To repeatedly perform path probing, telemetry status of all switches is reset to wait for initialization. For this purpose, the INT receiving terminal issues a reset signal, which is forwarded to the INT source in the reverse path. The reset signal is loaded onto the ACK field of the TCP message to minimize communication overhead. Each switch that receives the reset signal changes telemetry status to await initialization. Repeated execution of path probing may then be achieved, inserting telemetry values into the datagram as per steps 1-5 above.

The present invention uses the INT source to insert a telemetry header into the original data packet, thereby instructing the network devices along the way to add the INT metadata desired to be collected. The INT forwarding device inserts the acquired individual INT metadata therein for each hop during the network transmission. The INT receiving terminal extracts the telemetry header carrying the INT metadata and generates a probing report before processing the original data packet. The probe report contains hop-by-hop real-time network status information collected as the data packet passes through the network devices along the way. Meanwhile, the INT receiving terminal can also send a detection report to a telemetry server to finish path detection.

Claims

1. An INT-based lightweight path detection method, comprising the steps of:

each hop exchanger on the transmission link updates the current telemetry state to be ready for inserting an ID according to the INIT signal carried in the received ith data packet;

the next-hop switch forwards the received (i+1) data packet to the next-hop switch until the INT receiving terminal is reached;

the INT receiving terminal extracts a telemetry probe from the data packet and sends a telemetry value to a telemetry server;

after the INT source encapsulates the telemetry header into the (i+1) th data packet and inserts the ID, the telemetry status of the INT source is updated from the ready-to-insert ID to the inserted ID;

when the (i+2) th data packet from the same data stream reaches the INT source end, the INT source end forwards the data packet to the next hop exchanger, the exchanger in the state of being ready for inserting ID inserts ID into a telemetry header, and encapsulates the ID into the (i+2) th data packet, the state is updated to be the inserted ID, and the data packets are sequentially forwarded through the exchanger until reaching the INT receiving terminal;

2. The lightweight path detection method as in claim 1, wherein all switch states on the transmission link are set to wait for initialization prior to the step of the INT source encapsulating a telemetry header into an ith data packet containing an INIT signal.