Cisco Systems 6200 appendix Statistics, SLC 8CAP Operation

78-5296-02 10/02/98 Hardware Description 1

In the downstream direction, 11 rates are available ranging from 640 kbps to 7.168 Mbps. In the upstream direction, 9 rates are available, ranging from 91 kbps to 1.088 Mbps.

The modems on the CAP SLC train in sequence, first downstream, then upstream. Each modem first acquires the line. Then it tests the signal quality on the line by measuring the signal-to-noise ratio (SNR). It adds a preset margin, 6 dbm, to the SNR, and compares the resulting value to a table. If the value is acceptable, the modem trains at the configured rate. If not, the modem repeats the process, using the next lower transmission rate. The modem keeps trying to train indefinitely until it is successful.

Statistics

The SLC gathers signal quality statistics for network management purposes. It sends this information to the management system via the master SNMP agent. The SLC reports each of the following statistics to the management system for both upstream and downstream traffic:

•

•

•

Number of nonidle cells transmitted downstream

Number of nonidle upstream cells received with valid header checksum

Number of upstream cells received with invalid header checksum

•Number of errored seconds (this is the number of seconds in which at least one header checksum error or loss of cell delineation is observed), both upstream and downstream

Figure 1-10 SLC 8CAP Operation

Cell filter

Contention

and

arbitration

ATM NTC

Cisco

6200

Public

telephone

network

SLC

Port 1

POTS

CAPsplitter transceiver

POTS splitter

Port 2

Port 3

Port 8

ADSL

modem

12690

Cisco 6200 User Guide 1-23