US 5,347,524 AGranted

Protocol analyzer

AssigneeHewlett-Packard Company

InventorsColin S. I'Anson, Neil McKee, James R. Galloway

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Abstract

A protocol analyzer is provided for monitoring a selected communication connection being conducted in accordance with a predetermined protocol by the exchange of protocol data units between two entities over a data network. The analyzer includes a monitoring device for identifying protocol data units, a protocol-follower conditioned in dependence on said predetermined protocol and operative to follow the progress of the connection as it receives relevant protocol data units from the monitoring device, and an alarm indicating when the sequence of protocol data units diverges from the protocol. The protocol data units are passed through a FIFO store as they are used by the protocol-follower, so that on a protocol violation occurring, the sequence of protocol data units leading up to the violation can be extracted from the FIFO store and displayed. The protocol analyzer thus filters out protocol data units conforming to the relevant protocol so that only protocol data units violating the protocol, together with the immediately preceding protocol data units, are displayed.

Claims20

Dependent claims

A network protocol analyzer for monitoring a selected communication connection in accordance with a predetermined protocol between two entities by the exchange of protocol data units over a data network, said protocol being a cyclically-operating and having multiple states, a transition between said states are conditioned on said protocol data units, and said data network supporting a plurality of simultaneous communication connections between multiple pairs of said entities, said analyzer comprising:

(a) monitoring means for monitoring the network;
(b) connection-selection means connected to the monitoring means for selectively identifying said protocol data units relevant to said selected communication connection and for deriving protocol-units relevant to said selected communication connection;
(c) connection I.D. storing means connected to said connection-selection means for providing information for identifying said relevant selected communication connection;
(d) protocol-follower means including current-state memory means for storing a current protocol state of said selected communication connection, said protocol-follower means being conditioned in dependence on said states of said protocol, when one of said predetermined protocol data units is validly received for said current protocol state, a change to another of said states being caused in relation to said selected communication connection according to said protocol from the current protocol state as indicated by said current-state memory means, said protocol-follower means undating said current protocol state in said current-state memory means;
and
(e) alarm means in response to said protocol-follower means for providing an output indication when a said relevant protocol data unit, as represented by the corresponding protocol is an invalid one for said current protocol state.

3 more elements

Dependencies are inferred from the claim text.