Selecting the data you wish to collect:

The Pre-filters determine which of the frames that are
being sent over the Token Ring will be collected and
will appear in the realtime screen counters.

You select which frames by optionally specifying the
set of addresses you wish to collect, one or more
protocols (e.g. SAPs) you wish to collect, and a
pattern which must be matched by each frame to be
accepted.

Selecting an address filter:

In the From address field you can select a filter for
the source station address of frames to be accepted. 
Pressing ENTER allows you to select "any", to select a
particular station from the current list of names and
addresses, or to enter a new station address in hex and
supply a new name.

The To address field specifies the destination address
filter in a similar manner.

Selecting an address filter (continued):

You may select a combination of Broadcast or Non-
Broadcast frames for collection by checking the menu
items with those names.  

Checking "Reverse direction" permits frames in either
direction between the "To" and "From" stations to be
accepted.

Protocol filters:

You may select any number of protocols for collection
by checking their names as desired.  Each name
corresponds to one or more of the IEEE 802.2 SAPs
(Service Access Points).  In addition, MAC (Media Access
Control) frames may be included or excluded by checking
its name.

Pattern matching in frames:

A pattern is a 1 to 4 nibble (hex digit) value that you
enter using the hex values 0, 1, 2, .... D, E and F
for specific four bit fields, and X for "don't care".

You may choose whether to accept frames WITH the
pattern (select Equals) or WITHOUT the pattern (select
Not equals).

Pattern matching in frames (continued):

The offset for the pattern match may be specified to
begin either at the first byte of the frame ("Frame
relative"), or at the beginning of the LLC information
("Data relative").  The Data relative offset starts
with zero at the first byte following the source
address and optional routing information field.
