Atec Agilent-J2300E - Manual (Page 11)

11
ATM Capturing, Filtering and Searching
Capture Filters and Counters
Hardware counters and filters allow the user to select cells or AAL5 PDUs to
bring into the capture buffer. Even on a lightly loaded network, at ATM speeds
it does not take long to fill a data capture buffer. With data filtering, the user
can zero in on exactly the data the user needs to see. The filters examine every
cell in real time as it appears on the network. Since the filtering is done in the
hardware, nothing is missed, and the performance of the measurements and
user interface are not compromised.
Up to twelve hardware filters and counters can be enabled simultaneously and,
additionally, any two of the filters can be enabled to capture all the cells that
contain AAL5 PDUs. Flexible and user assisted menus can be used to define
specific filters, counters, and triggers based on protocol headers (see figure 2).
Examples include ATM, LAN over ATM (to RFC 2684/1483), Frame Relay
(FRF.5), LAN over Frame Relay over ATM (to RFC 2427/1490 and FRF.5
simultaneously), and Classical IP and ARP over ATM (RFC 2225/1577). Filter and
counter criteria can be used to start/stop the data capture and to center the
data in the buffer, the user can see what led up to an event and what followed
it. Filter criteria may also be used to ignore or store the data.
Filters are also used as counters to specify statistical measurements based
upon any part of the ATM header or payload on the line (network) side, the
equipment (user) side of the link, or both. The counter and filter results
provide the following:
• Number of cells that met the filter criteria
• Percentage of cells out of the total busy (assigned) cells on the line
• Percentage of bandwidth these cells occupied
• Throughput in kb/s of these cells
• Throughput in cells per second of these cells
Whatever filters or connectors the user selects or creates, the results are
automatically grouped in real time.
Figure 2: ATM Filter/Counter Properties.
ATM Testing (continued)