# US 5,710,760 A · Out-of-band control for performing a loopback test for asynchronous transfer mode (ATM) networks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,760 A - Document ID: US5710760A - Status: Granted - Kind: A - Application number: 08/564,700 - Filed: 1995-11-29 - Granted: 1998-01-20 - Earliest claimed: 1995-11-29 - Assignees: Lucent Technologies Inc. - Inventors: Keith Eugene Moll - Web page: https://patentgrep.com/patent/US5710760A ## CPC - H04L 43/50: Testing arrangements - H04Q 11/0478: {Provisions for broadband connections} - H04L 43/20: the monitoring system or the monitored elements being virtualised, abstracted or software-defined entities, e.g. SDN or NFV - H04L 2012/5619: {Network Node Interface, e.g. tandem connections, transit switching} - H04L 2012/5625: {Operations, administration and maintenance [OAM]} - H04L 2012/5628: {Testing} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) ## Abstract The loopback test consists of a user-application interface that connects the network operator to substantially all of the ATM points in the network. In operation, the network operator selects two ATM points as the loopback and source endpoints for the loopback test. The virtual path identification (VPI), virtual channel identification (VCI) and payload type indicator (PTI) that will be in the address header of the test cell when it arrives at the loopback endpoint location and the identification of the loopback endpoint are transmitted to the loopback endpoint in a setup message via a link from the UAI. The VPI, VCI and PTI that constitute the address header of a test cell injected at the source endpoint and destined for the loopback endpoint, and the location identification of the source endpoint are provided to the source endpoint in a setup message via a separate link from the UAI. The source endpoint formats a test cell based on this information and injects the cell into the network where it is routed based on the address header. The targeted loopback endpoint monitors the node identified in the setup message anticipating the arrival of the test cell. When the test cell arrives, it is captured by the loopback endpoint, examined to ensure that it is the appropriate loopback cell and retransmitted to the source endpoint. ## Claims ### Claim 1 A method for controlling a loopback test between ATM points in an ATM network comprising the steps of: selecting one of the ATM points as a loopback endpoint; transmitting first address information for a test cell to said loopback endpoint; selecting another of the ATM points as a source endpoint; transmitting second address information to said source endpoint; creating a nest cell at said source endpoint based on said second address information and injecting said cell into said network; capturing said test cell at said loopback endpoint based on said first address information; and looping back said test cell to said source endpoint. ### Claim 2 (depends on 1) The method of claim 1, wherein said first and second address information include virtual channel identifications and virtual path identifications. ### Claim 3 (depends on 1) The method of claim 1, further including the step of transmitting payload type information to said loopback endpoint and said source endpoint. ### Claim 4 (depends on 3) The method of claim 3, wherein said payload type is either an end-to-end cell type or a segment cell type. ### Claim 5 (depends on 3) The method of claim 3, wherein the step of creating a test cell is based on said payload type information. ### Claim 6 (depends on 1) The method of claim 1, further including the step of sending a teardown message to said loopback endpoint after said test cell is received at the source endpoint. ### Claim 7 (depends on 1) The method of claim 1, further including the step of reporting the results of the test to a system operator. ### Claim 8 (depends on 1) The method of claim 1, wherein the steps of transmitting includes the step of transmitting a setup message from a user-application interface to said source endpoint and said loopback endpoint over data links. ### Claim 9 (depends on 1) The method of claim 1, further including the step of transmitting a location identification to said source endpoint and a location identification to said loopback endpoint. ### Claim 10 (depends on 1) The method of claim 1, wherein the step of looping back includes the step of validating that said test cell is to be looped back. ### Claim 11 (depends on 10) The method of claim 10, wherein the step of validating includes the step of comparing a location identification for said source endpoint to a location identification for said loopback endpoint. ### Claim 12 A method for controlling a loopback test between ATM points in first and second networks comprising the steps of: selecting an ATM point in the first network as a loopback endpoint; selecting an ATM point in the second network as a source endpoint; providing test information to a first user-application interface in one of the first or second networks and to a second user-application interface in the other of the first or second networks; transmitting first address information for a test cell from said first user-application interface to said loopback endpoint; transmitting second address information from said second user-application interface to said source endpoint; creating a test cell at said source endpoint based on said address information and injecting said cell into said network; capturing said test cell at said loopback endpoint; and looping back said test cell to said source endpoint. ### Claim 13 (depends on 12) The method of claim 12, wherein said first and second address information includes virtual channel identifications and virtual path identifications. ### Claim 14 (depends on 12) The method of claim 12, further including the step of transmitting payload type information to said loopback endpoint and said source endpoint. ### Claim 15 (depends on 14) The method of claim 14, wherein said payload type is either an end-to-end cell type or a segment cell type. ### Claim 16 (depends on 14) The method of claim 14, wherein the step of creating a test cell is based on said payload type information. ### Claim 17 (depends on 12) The method of claim 12, further including the step of sending a teardown message to said loopback endpoint after said test cell is received at the loopback endpoint. ### Claim 18 (depends on 12) The method of claim 12, further including the step of reporting the results of the test to a system operator. ### Claim 19 (depends on 12) The method of claim 12, wherein the steps of transmitting includes the step of transmitting a setup message from the first user-application interface to said loopback endpoint and from said second user-application interface to said source endpoint over data links. ### Claim 20 (depends on 12) The method of claim 12, further including the step of transmitting a location identification to said source endpoint and a location identification to said loopback endpoint. ### Claim 21 (depends on 12) The method of claim 12, wherein the step of looping back includes the step of validating that said test cell is to be looped back. ### Claim 22 (depends on 21) The method of claim 21, wherein the step of validating includes the step of comparing a location identification for said source endpoint to a location identification for said loopback endpoint.