Sniffer Adaptive Application Analyzer: Adaptive Mode ... - NetScout

EARLY FIELD TRIAL Chapter 8
166 Sniffer Adaptive Application Analyzer
(b) Detail pane shows the detailed contents of the packet
currently selected in the Summary pane. Each layer of the protocol
is interpreted and displayed. Display the detailed protocol layers in
three different views – fully expanded decode, one-line summary,
or a mixture of the two.
By default, the application expands underlying protocol layers in
the Detail pane. To save viewing space, click the minus (-) sign in
front of the protocol sub-layer line. To expand the protocol display,
click the plus (+) sign.
NOTE: You can control the maximum number of lines allowed
in the Detail Display by right-clicking anywhere in the Decode
tab, selecting the Display Setup option, and setting the
Maximum # of Detail Lines option in the General tab of the
dialog box that appears.
(c) Hex pane shows the selected packet in hexadecimal and ASCII
(or EBCDIC) format.
When you select a packet on the Summary pane, or a detailed
protocol field in the Detail pane, the equivalent hexadecimal octets
in the packet are highlighted in the Hex pane. This quickly shows
you the correspondence between the protocol field and its
equivalent bytes in the packet.
Understanding Timestamps
Once a frame is received, a timestamp is attached. The timestamp
records the time according to the capturing device’s internal clock at the
moment it received the last byte of the frame. All displays of time (for
example, the Delta Time and Relative Time fields in the Summary pane)
are computed from the absolute value recorded with each frame.
As a general rule, the timestamps are:
Resolved to the nearest microsecond (see Table 8-2 for the
details).
Have accuracy that can vary from 20 microseconds to several
milliseconds, depending on ongoing operating system tasks and/or
ongoing processing of arriving packets.
IMPORTANT: 10/100/1000/10000-BaseT adapters timestamp packets
in software. Under most circumstances, this provides acceptable
performance – up to 250 microseconds granularity and correct packet
sequencing.