Cisco 3850 - GI2/0/4 RX POWER LOW ALARM

[Jeffrey Manego]

Hello. I have been having issues with this one interface GI2/0/4 on L3 Cisco 3850 switch that's been throwing out lots of Rx power low alarm; Operating value -26.7 dBm; Threshold value: -21.0 dbm logs.

My senior tech and myself have already troubleshoot below points:

 - Replace both fiber patch cable and SFP module from both the MDF and the IDF side 

 - Had vendor come out to check fiber runs from both sides

 - Changed to a different available port on the L3 switch and still throwing out the low power alarm logs

 - Changed to a different available port on the L2 switch from the IDF side; still throwing out low power alarm logs

Ran out of ideas. Anyone know what I can do to troubleshoot further on this Rx power low alarm errors?

Thank you in advance!

[Marvin Rhoads]

What is the distant end reporting as its Tx power?

[Jeffrey Manego]

FROM IDF SIDE. 1/1/2 is the interface having the issue with the Rx low power alarm

layer2switch# sh int transceiver detail
mA: milliamperes, dBm: decibels (milliwatts), NA or N/A: not applicable.
++ : high alarm, + : high warning, - : low warning, -- : low alarm.
A2D readouts (if they differ), are reported in parentheses.
The threshold values are calibrated.

High Alarm High Warn Low Warn Low Alarm
Temperature Threshold Threshold Threshold Threshold
Port (Celsius) (Celsius) (Celsius) (Celsius) (Celsius)
--------- ----------------- ---------- --------- --------- ---------
Gi1/1/1 40.4 90.0 85.0 -5.0 -10.0
Gi1/1/2 38.0 90.0 85.0 -5.0 -10.0

High Alarm High Warn Low Warn Low Alarm
Voltage Threshold Threshold Threshold Threshold
Port (Volts) (Volts) (Volts) (Volts) (Volts)
--------- ----------------- ---------- --------- --------- ---------
Gi1/1/1 3.29 3.60 3.50 3.10 3.00
Gi1/1/2 3.29 3.60 3.50 3.10 3.00

High Alarm High Warn Low Warn Low Alarm
Current Threshold Threshold Threshold Threshold
Port Lane (milliamperes) (mA) (mA) (mA) (mA)
--------- ---- --------------- ---------- --------- --------- ---------
Gi1/1/1 N/A 6.2 15.0 12.0 2.0 1.0
Gi1/1/2 N/A 5.7 15.0 12.0 2.0 1.0

Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port Lane (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ---- --------------- ---------- --------- --------- ---------
Gi1/1/1 N/A -5.1 -0.0 -2.9 -9.5 -13.4
Gi1/1/2 N/A -5.0 -0.0 -2.9 -9.5 -13.4

Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port Lane (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ---- --------------- ---------- --------- --------- ---------
Gi1/1/1 N/A -5.6 3.0 -0.0 -16.9 -21.0
Gi1/1/2 N/A -14.7 3.0 -0.0 -16.9 -21.0

[Tom Randstrom]

There is quite a difference in Receive power levels (approx 9dB) between the 2 links.  Is there an intermediate patch panel between the IDF and MDF locations?  Maybe dirty, old generation or damaged connectors,.

[Jeffrey Manego]

I have already swapped out the SFP modules and the fiber cables that go into the 1/1/2 interface (IDF) and the 2/0/4 interface (MDF).

I have also made sure the insides were cleaned out.

[Leo Laohoo]

How old is this fibre run and how long has this issue occurred? 

Post the complete output to the command "sh interface <PORTS>". 

NOTE:  Do not post screenshots.

[Jeffrey Manego]

The fiber run may have been before my time with this company, so unsure on that one. This issue has been occurring for several weeks now.

FROM MDF SIDE:
layer3switch#sh int g2/0/4
GigabitEthernet2/0/4 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 1ce8.5d88.9e04 (bia 1ce8.5d88.9e04)
Description: Link to IDF-D uscarf1rial385005 - Port-channel4
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX SFP
input flow-control is on, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:03, output 00:00:10, output hang never
Last clearing of "show interface" counters 1d00h
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Class-based queueing
Output queue: 0/40 (size/max)
5 minute input rate 59000 bits/sec, 26 packets/sec
5 minute output rate 59000 bits/sec, 26 packets/sec
1738713 packets input, 571914788 bytes, 0 no buffer
Received 165111 broadcasts (110833 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 110833 multicast, 0 pause input
0 input packets with dribble condition detected
3106777 packets output, 1257531389 bytes, 0 underruns
Output 463901 broadcasts (0 multicasts)
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

-------------------------------------------------------------------------------------

OUTPUT FROM IDF SIDE:

layer2switch#sh int g1/1/2
GigabitEthernet1/1/2 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is c472.950c.1532 (bia c472.950c.1532)
Description: Link to MDF uscarf1rial385001 - Port-channel4
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 1000Mb/s, link type is auto, media type is 1000BaseSX SFP
input flow-control is on, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:03, output hang never
Last clearing of "show interface" counters never
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Class-based queueing
Output queue: 0/40 (size/max)
5 minute input rate 62000 bits/sec, 28 packets/sec
5 minute output rate 53000 bits/sec, 23 packets/sec
3335419 packets input, 1341312144 bytes, 0 no buffer
Received 1763956 broadcasts (1271672 multicasts)
0 runts, 0 giants, 0 throttles
1 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 1271672 multicast, 0 pause input
0 input packets with dribble condition detected
1894557 packets output, 622236386 bytes, 0 underruns
Output 57926 broadcasts (0 multicasts)
0 output errors, 0 collisions, 4 interface resets
3137 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

[Leo Laohoo]

---

@Jeffrey Manego wrote:

Last clearing of "show interface" counters 1d00h

---

Nuts. 

Kindly post the complete output to the command "sh controller e Gi2/0/4".

[Jeffrey Manego]

layer3switch#sh controller e gi2/0/04
Transmit GigabitEthernet2/0/4 Receive
6915615320285 Total bytes 49748198439 Total bytes
4731940592 Unicast frames 143934950 Unicast frames
6871203290023 Unicast bytes 46057495916 Unicast bytes
110958540 Multicast frames 10206871 Multicast frames
39860037079 Multicast bytes 3073700464 Multicast bytes
39768679 Broadcast frames 4350397 Broadcast frames
4551993183 Broadcast bytes 617002059 Broadcast bytes
0 System FCS error frames 0 IpgViolation frames
0 MacUnderrun frames 0 MacOverrun frames
0 Pause frames 0 Pause frames
0 Cos 0 Pause frames 0 Cos 0 Pause frames
0 Cos 1 Pause frames 0 Cos 1 Pause frames
0 Cos 2 Pause frames 0 Cos 2 Pause frames
0 Cos 3 Pause frames 0 Cos 3 Pause frames
0 Cos 4 Pause frames 0 Cos 4 Pause frames
0 Cos 5 Pause frames 0 Cos 5 Pause frames
0 Cos 6 Pause frames 0 Cos 6 Pause frames
0 Cos 7 Pause frames 0 Cos 7 Pause frames
0 Oam frames 0 OamProcessed frames
0 Oam frames 0 OamDropped frames
45640943 Minimum size frames 30918625 Minimum size frames
72244955 65 to 127 byte frames 47401829 65 to 127 byte frames
59205577 128 to 255 byte frames 39449463 128 to 255 byte frames
51167064 256 to 511 byte frames 14430360 256 to 511 byte frames
210784161 512 to 1023 byte frames 5877290 512 to 1023 byte frames
4439708354 1024 to 1518 byte frames 18732497 1024 to 1518 byte frames
3916757 1519 to 2047 byte frames 1682702 1519 to 2047 byte frames
0 2048 to 4095 byte frames 0 2048 to 4095 byte frames
0 4096 to 8191 byte frames 0 4096 to 8191 byte frames
0 8192 to 16383 byte frames 0 8192 to 16383 byte frames
0 16384 to 32767 byte frame 0 16384 to 32767 byte frame
0 > 32768 byte frames 0 > 32768 byte frames
0 Late collision frames 0 SymbolErr frames
2577405 Excess Defer frames 0 Collision fragments
0 Good (1 coll) frames 0 ValidUnderSize frames
0 Good (>1 coll) frames 0 InvalidOverSize frames
0 Deferred frames 0 ValidOverSize frames
0 Gold frames dropped 548 FcsErr frames
0 Gold frames truncated
0 Gold frames successful
0 1 collision frames
0 2 collision frames
0 3 collision frames
0 4 collision frames
0 5 collision frames
0 6 collision frames
0 7 collision frames
0 8 collision frames
0 9 collision frames
0 10 collision frames
0 11 collision frames
0 12 collision frames
0 13 collision frames
0 14 collision frames
0 15 collision frames
0 Excess collision frames

LAST UPDATE 1456 msecs AGO