Atec Agilent-J2300E - Manual (Page 13)

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During the time that the cell table is not being sent, the Agilent Advisor will
send idle or unassigned cells. Send Control allows the contents of cell table to
be sent once or repetitively, or for AIS or idle cells to be sent. The peak cell
rate (PCR) of the cell table based traffic can be set from zero to the following
maximum values, all of which are 100% utilization for that interface. Also, for
ease of entry, a percent of utilization can be entered, such as 50% in place of
the cells per second value.
• 353,207 cells per second for STM-1/OC-3, STM-1e/EC-3 and UTP155
• 104,268 for DS3 HEC
• 96,000 cells per second for DS3 PLCP
• 80,000 for E3 HEC
• 72,000 for E3 PLCP
• 59,111 for ATM25 with X8 8kHz timing reference
• 59,259 for ATM25 without X8 8kHz timing reference
• 14,491 cells for J2
• 3,623 cells for DS1
• 4,528 cells for E1
To generate OAM cells, the user can use quick tests that include F4 and F5
segment or end-to-end cells with user-defined VPI[-VCI] values, they are
transmitted from the traffic generator. To generate cell errors, modify the
quick tests to add corrupted cells to the cell table.
The fields of the generated ATM cell header can be specified as follows:
• VPI values from 0 to 255 (UNI), or 0 to 4095 (NNI)
• VCI values from 0 to 65,535
• GFC values from 0 to 15 (UNI only, not applicable in NNI)
• PTI values from 0 to 7
• CLP values of 0 or 1
• HEC can be set to good (automatically calculated), bad, or user defined.
The generated ATM cell payload can be defined in hex, decimal, ASCII, or
“don’t care.” Errors can be inserted on any bit within any byte of the payload.
ATM Quality of Service (QoS) and Policing Tests
The Agilent Advisor has the ability to do various real-time tests and
measurements to check the performance of ATM networks. These fall into
two main categories – policing and traffic contract shaped test cell generation,
really mirror images of each other. In the case of policing, the Agilent Advisor
monitors live traffic and measures conformance to the traffic contract. Test cell
generation allows test traffic shaped to a traffic contract to measure the
network’s ability to deliver the promised QoS, i.e. is the network meeting its
SLA (service level agreement) obligations?
Policing, traffic shaping and traffic contract measurements
One of the most important premises of the deployment of ATM networks is
the ability to maintain a given level of QoS within the public ATM network.
ATM networks protect themselves by policing incoming traffic to check its
conformance with pre-determined traffic contract parameters. Some cells may
have to be discarded or “tagged” (marked to low priority) in order to protect
the traffic of other users of the ATM network.
ATM Testing (continued)