SYSTEM FOR TESTING ETHERNET PATHS AND LINKS WITHOUT IMPACTING NON-TEST TRAFFIC

Abstract

A system for testing Ethernet paths or links without adversely impacting non-test traffic. The system includes a test traffic generator that includes a scheduler that determines when a new test packet is generated. The test traffic generator includes a packet creator that builds a test packet and a transmitter for transmitting the test packet via the Ethernet path or link. The packet creator sends the test packet to the transmitter. The traffic generator includes a transmit credit block coupled to the transmitter or to the scheduler. The transmit credit block stores an amount of credits representing a number of bytes that are available to transmit and decrements the amount each time a non-test packet is communicated via the Ethernet path or link.

Claims

1. A system for testing a path in a network comprising: at least one test packet generator coupled to said path comprising: a scheduler to determine when a test packet is to be created based on an amount of non-test packets being transmitted on the path; and a packet creator to create the test packet; a transmitter to transmit the test packet on said path.

2. The system of claim 1, wherein the scheduler determines when the test packet is to be further created to achieve a pre-determined rate of transmission of said test packets.

3. The system of claim 1, wherein the pre-determined rate is selected so as to not impair non-test traffic.

4. The system of claim 1, wherein said at least one test packet generator is embedded in one of two ethernet devices coupled to said path.

5. The system of claim 1, wherein said amount of non-test packets is calculated by removing credits from a transmit credit block for each non-test packet, and wherein said transmission is delayed upon not having enough transmit credit available.

6. A method for testing a network path comprising: determining when a test packet is to be created based on an amount of non-test packets being transmitted on the path; and creating and transmitting said test packet on said path.

7. The method of claim 6, wherein said determining when the test packet is to be created is further based on achieving a pre-determined rate of transmission of said test packets.

8. The method of claim 7, wherein the pre-determined rate is selected so as to not impair non-test traffic.

9. The method of claim 6, wherein said creating and transmitting is done on one of two ethernet devices coupled to said path.

10. The method of claim 6, wherein said amount of non-test packets is calculated by removing credits from a transmit credit block for each non-test packet, and wherein said transmission is delayed upon not having enough transmit credit available.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The invention will be better understood from the following description of preferred embodiments together with reference to the accompanying drawings, in which:

[0007] FIG. 1 is a function block diagram of two Ethernet devices connected via an Ethernet link;

[0008] FIG. 2 is a functional block diagram of an Ethernet path between two Ethernet devices;

[0009] FIG. 3 is a functional block diagram of a test traffic generator in an Ethernet network comprising Ethernet links, an Ethernet path, and Ethernet devices;

[0010] FIG. 4 is a functional block diagram of a transmit generator and its functional blocks including a transmit block coupled to a transmit credit block; and

[0011] FIG. 5 is a functional block diagram of a transmit generator and its functional blocks like those shown in FIG. 4 except that the transmit credit block is responsive to a scheduler.

DETAILED DESCRIPTION

[0012] Although the invention will be described in connection with certain preferred embodiments, it will be understood that the invention is not limited to those particular embodiments. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims.

[0013] An embodiment of the invention includes the test traffic generator 14A, 14B, or 14C of FIGS. 3-5, which dynamically adapts its transmission characteristics in such a way as to not impair or impact the non-test traffic. Non-test traffic transmission characteristics (bandwidth, burst size, duration, etc.) may be bound by a bandwidth profile of some sort or may only be limited by the physical characteristics of the Ethernet medium (link speed, etc.).

[0014] The dynamic test traffic generator 14A may be embedded in an Ethernet device 10A or 10B, or it may be located adjacent to the Ethernet link 11 as a generator 14B or it may be located in-line of the Ethernet link 11 as a generator 14C. In the case of generator 14C, there are at least two Ethernet ports that carry non-test traffic. Generator 14C must therefore forward non-test traffic between its ports. This function does not relate to the operation of this invention. In all cases, the information about the amount of non-test traffic flowing in the same direction as the test traffic is made available to the dynamic test traffic generator 14A, 14B, 14C. As an example, if the test traffic generator 14B sends test traffic toward the Ethernet device 10B, the information about the amount of non-test traffic flowing from Ethernet device 10A toward the Ethernet device 10B is made available to the generator 14B. The Ethernet path 13 and the network 12 may or may not be present. If the network 12 and the Ethernet path 13 are not present, the two Ethernet links 11 are connected together and form a single Ethernet link (as in FIG. 1).

[0015] The transmit generator 20 of FIG. 4 includes multiple functional building blocks, such as a scheduler 21, a packet creator 22, a transmit block 23 and a transmit credit block 24. Other functional building blocks not related to this invention may be included but are not illustrated. The scheduler 21 determines when a new test packet needs to be generated. It instructs the packet creator 22, which builds a valid test packet and sends it to the transmit block 23. The function of the transmit block 23 depends on where the traffic generator 20 is located. In the case of the traffic generator 14A, embedded in Ethernet device 10A, the function of the transmit block 23 is to sending the generated traffic to other functions within Ethernet device 10A. The exact scope and operation of these other functions do not relate to this invention. In the case of the traffic generator 14C, the function of the transmit block 23 is to send the generated traffic to other functions within the device. These other functions do not relate to the operation of this invention. In the case of the traffic generator 14B, the transmit block 23 includes an Ethernet port and is responsible for sending the Ethernet test packet on the Ethernet link 25 attached to it. Two different preferred embodiments are illustrated in FIGS. 4 and 5.

[0016] In the case of FIG. 4, the transmit block 23 queries the transmit credit block 24 and transmits a test packet if sufficient credits are available. Credits represent the number of bytes to transmit. Headers, preamble and other Ethernet frame fields, such as the inter-frame gap, may be included in the credit count depending on the mode of operation of the bandwidth associated with the test. As an example, a layer 2 test includes at least Ethernet headers but not the inter-packet gap. If a transmission occurs, the appropriate amount of credit is debited from the transmit credit block 24. If there is not enough transmit credit available, the transmission is delayed until enough credit is available. The information about the amount of non-test traffic is provided to the transmit credit block 24 via line 26. The method by which this information is made available to block 24 is not relevant to the operation of this invention. Credits are removed from the transmit credit block 24 for each non-test packet. This effectively reduces the amount of credit available to allow transmission of test traffic. The credit total may become negative, due to excessive non-test traffic. This will further delay the transmission of test traffic because more credits will need to be added before enough credit is available to start the transmission of a test packet. Transmission credits are added to the transmit credit block 24 using methods and techniques that are not pertinent to this invention.

[0017] In the case of FIG. 5, the scheduler 21 queries the transmit credit block 24 and only sends a request to the packet creator 22 if sufficient credits are available. Credits represent the number of bytes to transmit. Headers, preamble and other Ethernet frame fields, such as the inter-packet gap, may be included in the credit count depending on the mode of operation of the bandwidth associated with the test. As an example, a layer 2 test would include at least Ethernet headers but not the inter-frame gap. If a request occurs, the appropriate amount of credit is debited from the transmit credit block 24. If not enough transmit credit is available, the request is delayed until enough credit is available. The information about the amount of non-test traffic is provided to the transmit credit block 24 via the line 26. The method by which this information is made available to block 24 is not relevant to the operation of this invention. Credits are removed from the transmit credit block 24 for each non-test packet. This effectively reduces the amount of credit available to allow transmission of test traffic. The credit total may become negative, due to excessive non-test traffic. This will further delay the transmission of test traffic because more credits will need to be added before enough credit is available to start the transmission of a test packet. Transmission credits are added to the transmit credit block 24 using methods and techniques that are not pertinent to this invention.

[0018] While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims.