Network fault analyzer

Abstract

Abstract 5 n7 A protocol analyzer, for use in monitoring packet sequences passing through a data network, includes context filter means comprising storage means 18 having permanently stored therein a set of state sequences corresponding substantially to a protocol carried by the network, and means for detecting (17) and indicating (20) when the sequence of packets diverges from a valid sequence of the stored set. The packet types are passed through a FIFO store (16) as they are matched against the stored sequences of states, so that on a violation, the sequence of packet types leading up to the violation can be extracted from the FIFO store and displayed. The context (or behavioural) filter thus filters out packet sequences conforming to the system protocols, so that only packets violating those protocols are displayed. An inverse mode can be provided in which only packet sequences conforming to the protocols are shown. A modest degree of user programmability can be added, to allow the user to effectively "tweak" the protocol tables. Two levels of operation can also be provided, giving "strong" filtering detecting only strictly protocol-violating sequences, or "weak" filtering giving automatic detection of permitted but unusual sequences as well.

Inventors

• 👤 Colin Stephen I'anson
• 👤 Neil Mckee

Bibliographic Details