PACKET COMMUNICATION APPARATUS AND COMMUNICATION LINE QUALITY ANALYZING METHOD

1 . A packet communication apparatus comprising:

a test packet header generating section configured to generate a header in an enable state;

a state machine configured to set said test packet header generating section to the enable state when a test packet transmission flag is set;

an FCS (Frame Check Sequence) calculating section configured to generate a data in a FCS field to add to said header, and to generate a variable length test packet having a plurality of FCS fields; and

a transmitting section configured to transmit test packets sequentially.

2 . The packet communication apparatus according to claim 1 , further comprising:

an FCS counter configured to perform a counting operation of a number of FCS fields added to said header, to end the counting operation when the counted number of FCS fields reaches a predetermined number and to notify to said state machine that the counted number of FCS fields reaches the predetermined number,

wherein said state machine switches said FCS calculating section and said transmitting section in response to the notice from said FCS counter.

3 . The packet communication apparatus according to claim 1 , further comprising:

a packet processing section configured to receive a packet from an outside, to determine a kind of the received packet and a packet length of the received packet, to determine a number of FCS fields from the packet length of the received packet when the received packet is a test packet, and to send the received packet and the determined number of FCS fields to said FCS calculating section;

an FCS calculation counter configured to count a number of times of calculation to the FCS fields by said FCS calculating section; and

a calculation result collating section configured to collate calculation results by said FCS calculating section sequentially when the count by said FCS calculation counter becomes equal to the determined number of FCS fields, and to output a collation result as a test packet data.

4 . The packet communication apparatus according to claim 3 , further comprising:

an analysis section configured to analyze the collation result to output a data indicating a region where an error exists.

5 . A packet communication apparatus comprising:

a packet processing section configured to receive packets from outside, to determine a kind of each of the received packets and a packet length of the received packet, and to determine a number of FCS (Frame Check Sequence) fields when the received packet is a test packet;

an FCS calculating section configured to receive the received packet and the determined number of FCS fields and to perform a calculation to the FCS fields;

an FCS calculation counter configured to count a number of times of the calculation which is repeated in said FCS calculating section;

a calculation result collating section configured to collate calculation results by said FCS calculating section sequentially when the count by said FCS calculation counter becomes equal to the determined number of FCS fields, and to output a collation result as a test packet data.

6 . A method of analyzing communication line quality, comprising:

receiving packets from outside;

determining a kind of each of the received packets and a packet length of the received packet, and determining a number of FCS (Frame Check Sequence) fields when the received packet is a test packet;

receiving the received packet and the determined number of FCS fields and performing a calculation to the FCS fields;

counting a number of times of the calculation which is repeated;

collating calculation results by said FCS calculating section sequentially when the count by said FCS calculation counter becomes equal to the determined number of FCS fields, to output a collation result as a test packet data.

7 . The method according to claim 6 , wherein said collating comprises:

analyzing the collation result to output a data indicating a region where an error exists.

8 . The method according to claim 6 , further comprising:

generating a header when a test packet transmission flag is set;

generating a data in a FCS field to add to said header;

counting a number of FCS fields added to the header;

transmitting a test packet when the count reaches a predetermined value.