IBM 2498B24 - System Storage SAN24B-4 Switch Installation, Service And User Manual page 53

Item
C
D
E
Testing a port, SFP, and fiber cable
The PortLoopbackTest command is used to verify the functional operation of the
switch by sending frames from the port "N" transmitter and looping them back
into the same port "N" receiver. The loopback is done at the parallel loopback path.
The path exercised in this test does not include the media or the fiber cable.
However if data transmission errors indicate that a port, SFP or cable are faulty,
you can use this command to determine whether the port is faulty. You can use
those results to isolate the problem to either the port or the SFP and cable
combination. If a port is faulty, the switch will need to be replaced. If the port is
not faulty, the problem is either with the SFP or the cable.
With this command, only one frame is transmitted and received at a time. No
external cable is required to run this test. The port LEDs flicker rapidly (green)
while the test is running.
The test performs the following operations:
1. Sets all ports for parallel loopback.
2. Creates a frame F of maximum data size (2,112 bytes).
3. Transmits the frame F through port "N".
4. Picks up the frame from the same port "N".
5. Checks the eight statistic error counters for nonzero values:
ENC_in, CRC_err, TruncFrm, FrmTooLong, BadEOF, Enc_out, BadOrdSet, DiscC3
6. Checks whether the transmit, receive, or class 3 receiver counters are stuck at
some value.
7. Checks whether the number of frames transmitted is not equal to the number
of frames received.
8. Repeats Steps 2 through 7 for all ports until one of the following conditions
are met:
a. The number of frames (or passcount) requested is reached.
b. All ports are marked bad.
At each pass, the frame is created from a different data type. If seven passes
are requested, seven different data types are used in the test. If eight passes
are requested, the first seven frames use unique data types, and the eighth is
the same as the first. The seven data types are:
CSPAT: 0x7e, 0x7e, 0x7e, 0x7e, ...
BYTE_LFSR: 0x69, 0x01, 0x02, 0x05, ...
CHALF_SQ: 0x4a, 0x4a, 0x4a, 0x4a, ...
QUAD_NOT: 0x00, 0xff, 0x00, 0xff, ...
CQTR_SQ: 0x78, 0x78, 0x78, 0x78, ...
CRPAT: 0xbc, 0xbc, 0x23, 0x47, ...
RANDOM: 0x25, 0x7f, 0x6e, 0x9a, ....
9. If the test indicates that all ports are good, the problem is associated with
either the cable or SFP.
10. Replace the SFP with an SFP known to be good.
Description
SFP
Bail
Cabled Fibre Channel ports
Chapter 3. Operating the switch
29