WO2009071030A1

WO2009071030A1 - Method for reporting device information, system and device for obtaining device information

Info

Publication number: WO2009071030A1
Application number: PCT/CN2008/073230
Authority: WO
Inventors: Fubing Li
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-11-30
Filing date: 2008-11-27
Publication date: 2009-06-11
Also published as: CN100579034C; CN101202664A

Abstract

A method for reporting device information, system and device for obtaining the device information of the communication field are disclosed. The method includes: receiving a detection message including responding id field sent from source device; sending responding message when the device itself is target device; judging whether to send the responding message according to the responding id field when the device itself is not the target device; if yes, sending the responding message to the source device; the responding message including the device information of the device itself, and the device information including device name at least. Thesystem includes source device and responding device. The device includes receiving module, the first judgment module, the second judgment module and responding message sending module. By carrying the device information in the responding message of the present invention, the source device is informed the device name and the current status of the device itself, and the management and maintenance for the network is facilitated.

Description

Method for reporting device information, system and device for acquiring device information

The present invention relates to the field of communications, and in particular, to a method for reporting device information, a system for acquiring device information, and a device. Say

Background technique

With the development of network technology, more and more people are using the network to handle daily life. Operators use the network to provide various services to consumers, and at the same time, they have put forward higher and higher requirements for network management capabilities. The management of the network is based on the mastery of the network operation information. If you cannot grasp the various information of the running equipment, you will not be able to access the equipment.

Proper management, and when an abnormality occurs in the network, it is impossible to take corrective actions to bring the network back to normal in time.

In the prior art, an ICMP (Internet Control Message Protocol) is provided, which is carried by an IP protocol (Internet Protocol), and the protocol number is 1. See the format of the ICMP packet provided in Figure 1. The 8-bit type field is used to describe the role and format of the ICMP packet. The 8-bit code field is used to specify the type of an ICMP packet. Check the sum field, as well as the data field. See Table 1 for the type of ICMP message.

Table 1

14 Time stamp Reply Timestamp Reply

15 Information Request Information Request

16 Information Reply In the prior art, some ICMP messages use the value of the code field to further describe different conditions. For example, when the type value is 3, the value of the code field is 0, the network is unreachable, and the code field is 1. The host is unreachable.

When the node processes the network traffic, it can advertise the ICMP response packet to the source node to the source node. In the prior art, there is a method for information acquisition, which uses ICMP to complete network exploration, such as a traceroute program, and the principle is as follows:

When the router receives an IP packet, if the TTL (Time To Live) is 0 or 1, the router does not forward the packet, discards the packet, and sends a timeout message to the source device. The ICMP response message, that is, the ICMP response message type value is 11, the code field is 0, and the source address of the ICMP response message is the IP address of the router.

In the process of implementing the present invention, the inventors have found that the above information acquisition method has at least the following problems:

The method of obtaining device information in the form of ICMP packets can only obtain the IP address of the router through which the packet passes. Usually, a router may have multiple IP addresses. This method can only obtain one of the IP addresses. An IP is not unified. It is difficult to locate a specific physical device based on the obtained IP; and other information about the device cannot be obtained. Summary of the invention

In order to facilitate the management and maintenance of the network, the embodiments of the present invention provide a method for reporting device information, and a system and device for acquiring device information. The technical solution is as follows:

A method for reporting device information, the method comprising:

Receiving, by the source device, a probe packet including a response identifier field;

When the device is the destination device, sending a response packet to the source device;

When it is not the destination device, it is determined according to the response identifier field whether it is necessary to send a response message; if yes, sending a response message to the source device;

The response message carries its own device information, and the device information includes at least a device name.

An embodiment of the present invention further provides a system for acquiring device information, where the system includes:

a source device, configured to send a probe packet including a response identifier field, and receive a response packet, and determine a corresponding device according to the device name in the device information carried in the response packet; The answering device is configured to receive the probe packet, and when it is the destination device, send a response packet to the source device; when it is not the destination device, determine, according to the response identifier field, whether the response packet needs to be sent; If yes, sending a response message to the source device; the response message carries device information of the response device, and the device information includes at least a device name.

Further, the embodiment of the present invention further provides a network device that reports device information, where the network device includes: a receiving module, configured to receive a probe packet including a response identifier field;

The first determining module is configured to determine, according to the destination address in the probe packet received by the receiving module, whether the device is the destination device;

a second determining module, configured to: when the first determining module determines that the device is not the destination device, determine, according to the response identifier field in the detection packet, whether the response packet needs to be sent to the source device;

a response message sending module, configured to: when the first determining module determines that it is a destination device, or when the determining result of the second determining module is that the response message needs to be sent to the source device, The source device sends a response packet, where the response packet carries its own device information, and the device information includes at least a device name.

The beneficial effects of the technical solutions provided by the embodiments of the present invention are:

By carrying the device information in the response packet, the source device is notified of the device name and current state of the device, which facilitates network management and maintenance. DRAWINGS

1 is a schematic diagram of a format of an ICMP packet provided by the prior art;

2 is a schematic diagram of a data format of a custom protocol provided by Embodiment 1 of the present invention;

3 is a flowchart of a method for reporting device information according to Embodiment 1 of the present invention;

4 is a schematic structural diagram of a network provided by Embodiment 1 of the present invention;

FIG. 5 is a schematic diagram of another network structure provided by Embodiment 1 of the present invention; FIG.

6 is a flowchart of a method for reporting device information according to Embodiment 2 of the present invention;

7 is a schematic diagram of a system for acquiring device information according to Embodiment 3 of the present invention;

FIG. 8 is a schematic diagram of a network device for reporting device information according to Embodiment 4 of the present invention. detailed description

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

After receiving the probe packet including the response field, the device in the embodiment of the present invention, when it is the destination device, The source device sends a response packet; when it is not the destination device, it determines whether it needs to send a response packet according to the response identifier field; if yes, sends a response packet to the source device, where the response packet carries its own device information, and the device The information includes at least the device name, so that the source device can confirm the corresponding device according to the device name, which facilitates network management and maintenance.

Example 1

The embodiment provides a method for reporting device information, where the device information includes at least a device name, and may also include local information and/or TTL. The local information refers to the number of lost packets on the inbound interface, the number of dropped packets on the outbound interface, and the lost interface. Number of bytes, number of bytes lost on the outbound interface, total bandwidth of the inbound interface, total bandwidth of the outbound interface, idle bandwidth of the inbound interface, free bandwidth of the outbound interface, reason for forwarding failure, forwarding attribute information, and MTU (Maximum Transmission Unit) One or more. In addition, the device information may include the device's IP address or MAC (Media Access Control) address, or may not include its IP address or MAC address. The device name may also be represented as the device's MAC address. Or an IP address, in order to facilitate identification, a name with geographical location information is preferred as the device name.

This embodiment defines an extensible protocol. The data format of the protocol defines multiple types of fields. As shown in Table 2, the device information is carried in the type field, and the network is managed and maintained according to the device information.

Table 2

TTL 11 lByte The TTL value carried in the packet received by the device failed to be forwarded due to 12 lByte 1: route lookup failed; 2: QoS; 3: L2 encapsulation information could not be found; 4: security check failed; 5: URPF failure forwarding attribute information 13 lByte 1: Take the default route; 2: Load sharing; 3: Standby link of the primary and backup links; 4: Standby link of the primary and backup links; 5: QoS for entering the tunnel (GRE, MPLS, etc.) Quality of Service, monthly quality; URPF is Unicast Reverse Path Forwarding, unicast reverse path forwarding; GRE is Generic Routing Encapsulation, general routing encapsulation.

The bandwidth unit in this embodiment is not fixed, and 1 indicates bits, 2 indicates kbits, 3 indicates Mbits, 4 indicates Gbits, and 5 indicates 10 Gbits.

For example: A message can carry multiple data at the same time. One data consists of three parts: type, length and value. The number of lost packets on the inbound interface sent by the response device (the device name is SHANGHAI) is 100, and the number of lost packets on the outbound interface is 200. For the data format, see Figure 2, where the type is 1, the device name is displayed. The length is 8 and the value is SHANGHAI. When the type is 2, the number of packets lost on the inbound interface is 8 and the value is 100. When the type is 3, the number of packets lost on the interface is 8. The length is 8 and the value is 200. .

Referring to FIG. 3, the method for reporting device information includes:

S101: The source device sends a probe packet to the next hop device, where the probe packet includes a response identifier field.

The detection packet may be a self-defined probe packet or an ICMP packet. The custom probe packet may have an ICMP packet function or a packet with a response identifier field. After receiving the probe packet, the one-hop device can determine whether to return its device information to the source device according to the response identifier field.

The source device can pre-configure the setting rule of the response identifier field with other devices. For example: If the source device only wants to obtain the device information of the destination device, add the identifier "E" in the response identifier field of the probe packet to indicate the intermediate device. The device does not respond to the probe packet. If the identifier "E" is not added to the response identifier field of the probe packet, the source device wants to obtain the device information of each device on the path. Alternatively, adding "1" in the response identification field of the probe message indicates that a response is required, and adding "0" indicates that no response is required. In this embodiment, whether or not the identifier Έ is added to the response identifier field is used as a basis for requesting a response.

S102: After receiving the foregoing probe packet, the next hop device determines whether it is the destination device according to the destination address in the probe packet. If yes, execute S106; otherwise, execute S103.

S103: Determine, according to the response identifier field, whether a response message needs to be sent to the source device, and if yes, execute S104; otherwise, execute S105. S104: Send a response message to the source device, where the response message carries device information of the device, and then execute S105. The local information in the device information is pre-stated and saved on the device. For example, when the device finds that the checksum of the received packet is incorrect, the device discards the packet from the inbound interface and records the number of discarded packets (the number of dropped packets) and the reason for the discarding. If the queue is full, the packets that need to be forwarded are discarded from the outbound interface. The number of discarded packets and the cause of the discarded packets are recorded.

S105: Modify the TTL in the probe packet, and reduce the original TTL by 1, and forward the modified probe packet to the next hop device, and return to S102.

S106: The destination device sends a response packet to the source device, where the response packet carries device information of the device.

S107: After receiving the response packet, the source device extracts the device information carried in the response packet.

The above-mentioned respective numbers are only for convenience of reference, and do not limit the order of the processes, for example: S104 can also be executed after S105.

The source device analyzes based on the extracted device information:

1) If the device information carried in the response message is the device name, the source device will be able to know which device is online.

2) If the device information carried in the response packet is the device name and local information, the source device will know the status of the device corresponding to the device name, for example:

When the response packet carries the number of lost packets on the inbound/outbound interface, the source device can analyze which device on the path affects the transmission of data, voice, or image according to the number of packets lost;

When the response packet carries the reason for forwarding failure and forwards the attribute information, the source device may find a solution according to the reason;

When the response packet carries the bandwidth usage (the total bandwidth of the inbound interface, the total bandwidth of the inbound interface, the idle bandwidth of the inbound interface, and the idle bandwidth of the inbound interface), the source device can analyze whether the device has reached the transmission bottleneck according to the bandwidth usage.

When the response packet carries the MTU of the device, the source device can know whether the device will cause packet fragmentation.

3) If the device information carried in the response packet is the device name and TTL, the source device can know the sequence of each device on the path according to the TTL in the response packet returned by each device.

4) If the device information carried in the response message is the device name, local information, and TTL, the source device will be able to analyze the information in 1) to 3) above.

Referring to the network structure diagram provided in Figure 4, the source device Beijing sends a probe packet to the destination device Shenzhen. The intermediate device Shanghai and Guangzhou are used as an example. The above method is as follows:

1) The source device Beijing sends a probe packet, the TTL of the probe packet is 64, and the identifier E is not carried in the response identifier field.

2) After the intermediate device Shanghai receives the above probe packet, the probe packet does not carry the identifier E, indicating the middle. The device needs to respond to the probe packet, and the intermediate device Shanghai extracts the TTL=64 in the probe packet, and decrements 64 to get 63, and sends a response packet to the source device Beijing, and the response packet carries the intermediate device. The device name is Shanghai and TTL = 63; the TTL of the probe packet is 63, and the modified probe packet is forwarded to the next hop device (the intermediate device Guangzhou);

3) After receiving the probe packet, the intermediate device Guangzhou sends a response message to the source device Beijing, which carries the device name of the intermediate device, Guangzhou and TTL = 62; In the text, the TTL is 62, and the next hop device (the destination device Shenzhen) forwards the modified probe packet. 4) After receiving the probe packet, the destination device Send sends a response packet to the source device Beijing, the response packet. The name of the device carrying the device for this purpose is Shenzhen and TTL = 61;

5) After receiving the response message from Shanghai, the source device Beijing continues to wait because it is not a response message from Shenzhen, until it receives a response message from Shenzhen or waits for a timeout. After receiving all response messages, the source device According to the TTL (Shanghai TTL=63 Guangzhou TTL=62, Shenzhen TTL=61) of the response message returned by Shanghai and Guangzhou Shenzhen, Beijing can determine that the order of the path is Beijing-Shanghai- Guangzhou-Shenzhen.

See Figure 5, from Beijing to Shenzhen, for example: The host name of the device in Beijing is Beijing, the IP address is 10.1.1.1; the host name of the device in Shanghai is Shanghai, the IP address is 10.2.2.2, and the inbound interface is lost. The number of InBoundLoss is 0, and the number of outbound packets (OutBoundLoss) is 222. The host name of the device in Shenzhen is Shenzhen, the IP address is 10.3.3.3, the number of lost packets on the inbound interface is 0, and the number of dropped packets on the outbound interface is 0. By entering: C:\Documents and Settings\Administrator>tracert 10.1.1.1, you will get the following information:

Tracing route to 10.111.138.87 over a maximum of 30 hops

No IP HostName InBoundLoss OutBoundLoss

1 10.2.2.2 Shanghai 0 222

2 10.3.3.3 Shenzhen 0 0

Through this information, the source device can know the list of host names through which the probe packets pass. By rationally planning the device name, the operator can quickly know which areas or computer rooms a data stream has passed. In addition, through the information in the packet on the inbound/outbound interface, it can be known that there is packet loss on the outbound interface of the intermediate Shanghai device, which may be the cause of mosaic of the video.

In this embodiment, the device information of the device is carried in the response packet, so that the source device knows that the device is online through the device name in the device information, and the device is managed by the device name, and the readability is good, which facilitates network management. And maintenance. At the same time, through the other information in the device information (such as local information), the source device can know the status of the device and help solve problems in the network.

Example 2 Referring to FIG. 6, the embodiment provides a method for reporting device information, which is implemented by extending an ICMP response mechanism, including:

S201: The source device sends an ICMP probe packet including a TTL to the next hop device.

S202: After receiving the ICMP probe packet, the next hop device checks whether the TTL in the ICMP probe packet is 1, if yes, execute S203; otherwise, execute S204.

S203: Send an ICMP timeout packet to the source device, and carry the device information of the device.

The TTL in the ICMP probe packet is the response identifier field, and TTL=1 indicates that the response packet needs to be sent.

If the TTL is not 1, the device does not need to send a response packet. The response packet in this embodiment is an ICMP timeout packet. The device information is the same as the device information in the first embodiment, and is not described here.

S204: The TTL of the ICMP probe packet is decreased by 1, and the ICMP probe packet with the TTL minus one is sent to the next hop device, and the process returns to S202.

S205: After receiving the ICMP timeout packet, the source device extracts the device information in the ICMP timeout packet.

The source device can also obtain the device sequence in the path in the order in which the ICMP time-out packets are received. For example, the source device sets the TTL of the first ICMP probe packet to 1, and receives the ICMP sent by the destination device. After the timeout packet is received, the device name in the device information is recorded. Then, the ICMP probe packet with the TTL of 2 is sent. After receiving the ICMP timeout packet sent by the destination device, the device name in the device information is recorded again, and so on. Get the order of the devices on the path.

Similarly, according to other information in the device information, the source device can also analyze the status of the current device.

At the same time, the TTL of the ICMP probe packet can also indicate that the device is the destination device. That is, the source device only needs to return the response packet, that is, the ICMP timeout packet in this embodiment.

The device sends an ICMP probe packet carrying the TTL, and the device that receives the ICMP probe packet with the TTL of 1 sends an ICMP timeout packet to the source device, and carries the device information of the device in the ICMP timeout packet, according to the device. The state of the information analysis device facilitates network management and maintenance.

Example 3

Referring to FIG. 7, this embodiment provides a system for acquiring device information, including:

The source device 301 is configured to send a probe packet including a response identifier field to the next hop device, and receive the response packet, and determine a corresponding device according to the device name in the device information carried in the response packet.

The response device 302 is configured to receive the probe packet sent by the last hop device, and send a response packet to the source device 301 when the device is the destination device. If the device is not the destination device, determine whether the response packet needs to be sent according to the response identifier field. If yes, send a response message to the source device 301; the response message carries device information of the response device 302, and the device information includes at least the device name. When the answering device 302 of the system is multiple, the answering device 302 specifically includes:

The receiving module 3021 is configured to receive a probe packet sent by the last hop device.

The determining module 3022 is configured to determine, according to the destination address in the probe packet, whether the device is the destination device, and if not, determine, according to the response identifier field, whether the response packet needs to be sent to the source device 301.

The response message sending module 3023 is configured to: when the judgment result of the determining module 3022 is that the response message needs to be sent to the source device 301, extract the life cycle in the probe message, decrement the life cycle by 1, and send a response message to the source device 301. The response message carries its own device information, and the device information includes the device name and the life cycle after being decremented by one;

The detection packet forwarding module 3024 is configured to modify the detection packet received by the receiving module 3021 when the judgment result of the determining module 3023 is that it is not the destination device, and reduce the lifetime of the detection packet by one to the next hop. The device forwards the modified probe packet.

The system provided in this embodiment can obtain the device information of the response device by sending the probe packet, and manage the network according to the device information, thereby improving the management efficiency and facilitating the network maintenance.

Example 4

Referring to FIG. 8, this embodiment provides a network device for reporting device information, including:

The receiving module 401 is configured to receive a probe packet including a response identifier field.

The first determining module 402 is configured to determine, according to the destination address in the probe packet received by the receiving module 401, whether the device is 0 or not;

The second determining module 403 is configured to: when the first determining module 402 determines that the device is not the destination device, determine, according to the response identifier field in the probe packet, whether the response packet needs to be sent to the source device;

The response message sending module 404 is configured to: when the first determining module 402 determines that it is the destination device, or when the second determining module 403 determines that the response message needs to be sent to the source device, send a response message to the source device. The response message carries its own device information, and the device information includes at least the device name.

The response message sending module 404 specifically includes:

The response message sending confirmation unit 4041 is configured to: when the first determining module 402 determines that it is the destination device, or when the second determining module 403 determines that the response message needs to be sent to the source device, confirm that the source device is required to be sent to the source device. Send a response message;

The response message sending unit 4042 is configured to: when the response message sending confirmation unit 4041 confirms that the response message needs to be sent to the source device, extract the life cycle in the probe message, decrement the life cycle by 1, and send the response message to the source device. The response message carries its own device information, and the device information includes the device name and the life cycle after being decremented by one;

Correspondingly, the network device that reports the device information may further include:

The probe packet forwarding module 404 is configured to: when the first determining module 402 determines that it is not the destination device, The probe packet received by the module 401 is modified, and the lifetime of the probe packet is decremented by one, and the modified probe packet is forwarded to the next hop device.

Further, the response identifier field carried by the detection packet received by the receiving module 401 is specifically a life cycle. Correspondingly, the second determining module 403 is specifically configured to determine whether the lifetime of the detection packet is 1, and if so, The source device sends a response packet; otherwise, it does not need to send a response packet to the source device.

The network device that reports the device information provided by the present embodiment can send a response packet to the source device according to the information in the probe packet, and notify the source device of the device information, so that the source device can manage and maintain the network according to the device information.

The above embodiment carries the device information by sending the response message to the source device, so that the source device can obtain the device state in the current network, which enhances the management and maintenance of the network.

At the same time, the technical solution provided by the foregoing embodiments can obtain the information of the managed device without using the network management system, and solve the problem that the network management system is not easy to deploy, and the network management can only manage to a limited number of devices, and cannot obtain the jurisdictional scope. The information about the device and the actual forwarding path for obtaining network traffic are difficult.

All or part of the technical solutions provided by the above embodiments may be implemented by software programming, and the software program is stored in a readable storage medium such as a hard disk, an optical disk or a floppy disk in a computer. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

Claim

A method for reporting device information, the method comprising:

The method for reporting device information according to claim 1, wherein the device information further includes the number of lost packets on the inbound interface, the number of lost packets on the outbound interface, the number of bytes lost on the inbound interface, and the number of bytes lost on the outbound interface. One or more of the total bandwidth of the inbound interface, the total bandwidth of the inbound interface, the idle bandwidth of the inbound interface, the idle bandwidth of the outbound interface, the reason for the forwarding failure, the forwarding attribute information, and the maximum transmission unit.

Correspondingly, the method further includes:

After receiving the response packet, the source device extracts device information carried in the response packet;

Determining, according to the device information, a status of the device corresponding to the device name.

The method for reporting device information according to claim 1, wherein the identifier of the response identifier field is a response required;

The device information further includes a life cycle, where the life cycle is a value obtained by subtracting 1 from a life cycle extracted from the detection message;

Correspondingly, when it is not the destination device, if the result of the determination is that the response message needs to be sent, the method further includes:

The lifetime of the probe packet is modified, and the lifetime of the probe packet is decremented by 1, and the modified probe packet is forwarded to the next hop device.

The method for reporting device information according to claim 3, wherein the method further comprises: the source device receiving each response message, and extracting a life cycle and a device in each response message. Name; Determine the order of devices from the source device to the destination device according to each life cycle. The method for reporting device information according to claim 1, wherein the response identifier of the probe message The field is specifically a life cycle. Correspondingly, the step of determining, according to the response identifier field, whether a response message needs to be sent is specifically:

Determine whether the lifetime of the probe packet is 1. If yes, the response packet needs to be sent; otherwise, the response packet does not need to be sent.

A system for acquiring device information, characterized in that the system comprises:

a source device, configured to send a probe packet including a response identifier field;

The answering device is configured to receive the probe packet, and when it is the destination device, send a response packet to the source device; when it is not the destination device, determine, according to the response identifier field, whether the response packet needs to be sent; If yes, sending a response message to the source device; the response message carries device information of the response device, where the device information includes at least a device name;

The source device is further configured to receive the response packet, and determine a corresponding device according to the device name in the device information carried in the response packet.

The system for acquiring device information according to claim 6, wherein the number of the response devices is multiple, and each of the response devices specifically includes:

a receiving module, configured to receive the probe packet sent by the last hop device;

The determining module is configured to determine, according to the destination address in the probe packet, whether the device is the destination device, and if not, determine, according to the response identifier field, whether the response packet needs to be sent to the source device.

a response message sending module, configured to: when the determining result of the determining module is that the response message needs to be sent to the source device, extract a life cycle in the detecting message, and reduce the life cycle by one, The source device sends a response packet, where the response packet carries its own device information, where the device information includes a device name and a life cycle after being decremented by 1; a probe packet forwarding module is used to determine the result of the determining module. If the device is not the destination device, the detection packet received by the receiving module is modified, and the lifetime of the probe packet is decremented by one, and the modified probe packet is forwarded to the next hop device.

8. A network device for reporting device information, wherein the network device comprises:

a receiving module, configured to receive a probe packet including a response identifier field;

a second determining module, configured to: when the first determining module determines that it is not a destination device, according to the detecting The response identifier field in the packet determines whether a response packet needs to be sent to the source device.

The network device for reporting device information according to claim 8, wherein the response message sending module specifically includes:

The response message sending confirmation unit is configured to: when the first determining module determines that it is the destination device, or when the second determining module determines that the response message needs to be sent to the source device, confirm the need Sending a response message to the source device;

a response message sending unit, configured to: when the response message sending confirmation unit confirms that the response message needs to be sent to the source device, extract a life cycle in the probe message, and reduce the life cycle by one, The source device sends a response packet, where the response packet carries its own device information, where the device information includes a device name and a life cycle after being decremented by one;

Correspondingly, the network device that reports the device information further includes:

The detecting packet forwarding module is configured to: when the first determining module determines that the device is not the destination device, modify the detection packet received by the receiving module, and reduce the lifetime of the detecting packet by one, The next hop device forwards the modified probe packet.

The network device for reporting device information according to claim 8, wherein the response identifier field carried by the detection packet received by the receiving module is specifically a life cycle, and correspondingly, the second determining module is specific It is used to determine whether the lifetime of the probe packet is 1. If yes, the response packet needs to be sent to the source device; otherwise, the response packet is not sent to the source device.