Network Equipment Technologies 500 - Manual (Page 11)

Introduction 1-5
This default can be overridden from the command line as follows:
These overrides should not be used unless problems are experienced with the default.
The size of the buffer therefore depends on the amount of memory (RAM) available in
the computer, and the amount used by other programs. The buffer size is displayed on
the startup screen. Multiply this by four to determine the number of traffic items that
can be stored.
Display
Traffic is displayed on the screen according to the current settings of layer 2 and layer 3
decoding and display (L2, L3, Long, Med, and Short commands). You can pause the
display to examine messages and scroll the display backwards and forwards. See Chapter
4 — Commands for more information.
Basic Rate interface
To understand the information displayed by the Basic Rate PAP you must understand
Service Access Point Identifiers (SAPIs), Terminal Endpoint Identifiers (TEIs) and
Connection Endpoint Suffices (CESs). A data link connection is identified by a SAPI and
a TEI. The SAPI defines which part of the bit within a terminal is talking and can have
three different values:
0 LAPD link for ISDN calls
16 LAPB link for X.25 calls
63 management bit which manages TEIs
The TEI is a unique address (for a particular ISDN connection) assigned to a terminal.
The analyzer displays two types of TEI:
Fixed set physically on a terminal, usually by DIP switches or non-volatile
storage. You must ensure that each fixed TEI terminal has a unique
address; if two terminals have the same address, neither will work.
Automatic worked out dynamically by negotiation between network and
terminal.
The TEI and SAPI combine to make a physical address that is encoded into layer 2 frames.
Layer 3 refers to this combination by a CES. This is a number between 0 and 255 which
at any time uniquely identifies a particular SAPI/TEI combination.
PAPXXXX REAL forces the PAP software to use conventional memory and will
not operate if insufficient conventional memory is available.
PAPXXXX VIRTUAL forces the PAP software to use Extended or Expanded memory
and will not operate if memory is not available.