Cisco ONS 15454 SDH - Manual (Page 21)

15-21
Cisco ONS 15454 SDH Reference Manual, R4.6
April 2008
Chapter 15 Performance Monitoring
15.6 Performance Monitoring for Optical Cards
15.6 Performance Monitoring for Optical Cards
The following sections define performance monitoring parameters and definitions for the STM-1,
STM1 SH 1310-8, STM-1E, STM-4, STM4 SH 1310-4, STM16 SH AS 1310, STM16 LH AS 1550,
STM16 EH 100 GHz, STM64 IO 1310, STM64 SH 1550, STM64 LH 1550, STM64 LH ITU 15xx.xx,
TXP_MR_10G, TXP_MR_2.5G, TXPP_MR_2.5G, and MXP_2.5G_10G cards.
On all STM-N optical cards errors are calculated in bits instead of blocks for B1 and B3. This means
there could possibly be a slight difference between what is inserted and what is reported on CTC. In
STM4 for example, there are approximately 15000 to 30000 bits per block (per G.826). If there were two
bit errors within that block, the standard would require reporting one block error whereas the STM-N
cards would have reported two bit errors.
When a tester inputs only single errors during testing, this issue would not appear because a tester is not
fast enough to induce two errors within a single block. However, if the test is performed with an error
rate, certain error rates could cause two or more errors in a block. For example, the STM4 is roughly 622
Mbps and the block in the STM4 has 15000 bits, there would be about 41467 blocks in a second. If the
tester inputs a 10e-4 error rate, that would create 62200 errors per second. If the errors are distributed
uniformly, then CTC could potentially report two bit errors within a single block. On the other hand, if
the error ratio is 10e-5, then there will be 6220 errors per second. If the errors are not distributed
uniformly, then CTC might report one bit error within a single block. In summary, if the errors are
distributed equally, then a discrepancy might be seen with the standard when a tester inputs 10e-4 or
10e-3 error rates.
Rx Longs Counter for the number of received frames that exceed the
maximum valid packet length of 1518 bytes.
Rx Total Errors Total number of receive errors.
Rx CRC Errors Number of packets with a CRC error.
Rx Input Drop Packets Number of received packets dropped before input.
Rx Input Abort Packets Number of received packets aborted before input.
Tx Pre HDLC Bytes Number of bytes transmitted prior to the bytes HLDC encapsulation
by the policy engine.
Tx Post HDLC Bytes Number of bytes transmitted after the bytes HLDC encapsulation by
the policy engine.
Tx Packets Number of packets transmitted since the last counter reset.
Port Drop Counts Number of received frames dropped at the port level.
Table 15-22 ML-Series POS Ports Parameters (continued)
Parameter Meaning