OpenVMS Cluster Systems - OpenVMS Systems - HP

Troubleshooting the NISCA Protocol
F.10 Setting Up an HP 4972A LAN Protocol Analyzer
Table F–12 (Cont.) Tracing Datagrams
Step Action
2 Use the distributed enable function to allow the same event to be captured by several
LAN analyzers at different locations. The LAN analyzers should start the data capture,
wait for the distributed enable message, and then wait for the explicit trigger event or the
distributed trigger message. Once triggered, the analyzer should complete the distributed
trigger function to stop the other LAN analyzers capturing data.
3 Once all the data is captured, locate the sequence number (for nodes running the NISCA
protocol Version 1.3 or earlier) or the extended sequence number (for nodes running the
NISCA protocol Version 1.4 or later) for the datagram being retransmitted (the datagram
with the REXMT flag set). Then, search through the previously captured data for another
datagram between the same two nodes (not necessarily the same LAN adapters) with the
following characteristics:
• Protocol type set to 60–07
• Same DX header as the datagram with the REXMT flag set
• TR/CC flag set to 0
• REXMT flag set to 0
• Same sequence number or extended sequence number as the datagram with the
REXMT flag set
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