Electrical computers and digital processing systems: multicomput – Computer network managing
Reexamination Certificate
1998-06-16
2001-05-01
Harrell, Robert B. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Computer network managing
C709S249000
Reexamination Certificate
active
06226674
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention pertains to the field of Open Systems Interconnect (OSI) compliant computer systems, including any OSI-compliant telecommunication management systems. More particularly, the present invention pertains to a method of determining whether an element in a network of OSI-compliant systems is reachable from an interrogating system.
2. Description of Related Art
The inclusion of OSI stacks in a telecommunication management network, which encompasses all transport network elements (NEs), is a relatively new but complex technology lacking in robust diagnostic tools. New tools are needed that can save time in troubleshooting network failures. One such tool is a way of eliminating misleading reports of the result of a ping request, i.e. a request issued by a user through a requesting system to determine whether a destination system is reachable, at the time, from the user's location.
In the prior art, when a user pings a destination system under OSI, the destination system is to echo the ping, using an OSI echo function. If the requesting system does not receive an echo in response to a ping, the requesting system reports the failure to the user. However, a destination system may be reachable and yet not able to echo a ping; in order to echo a ping, a destination system must support the OSI echo function. Thus, the failure report according to the prior art may be misleading.
OSI uses a so-called Connectionless Network Protocol (CLNP), which has three basic building blocks: the CLNP echo function, the route recording function, and the error reporting function, as specified in ISO 8473. Under current practice the error reporting function is not enabled and its output is not coordinated with the other functions when a pinging system formulates an OSI ping user response. Thus, a user will receive a misleading result when a pinged destination system is reachable but does not support the CLNP echo function, since although the destination system will be reached by the request, the request will be discarded.
What is needed is a method of executing the OSI ping function to determine status of a destination system and analyzing the result so as not to report an abnormal status merely because the destination system does not have a CLNP echo capability.
SUMMARY OF THE INVENTION
According to the present invention, misleading reports of the result of pinging a destination system are eliminated by pinging the destination system by issuing, with error reporting and route recording enabled, a CLNP echo request protocol data unit (PDU). Then have the OSI ping analysis function interpret the echo response using error reporting PDUs in a way that determines whether the destination system has CLNP echo capability. After enabling error reporting and route recording, and after pinging a destination system by issuing a CLNP echo request PDU, the full OSI ping analysis according to the present invention proceeds according to the pseudocode:
If no response, then result=fail;
Else if CLNP echo response PDU received, then result=success;
Else if error report received with reason=“function not supported” and source address=ping destination address, then result=success;
Else result=fail, intermediate system;
By enabling error reporting when the echo request is issued, the destination system is forced to respond with an error report including the message, function not supported. By coordinating this error response with the request, the OSI ping analysis function can determine that although the destination system does not support the echo function, the destination system is still reachable.
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Harrell Robert B.
Vu Thong
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