Fibre connection working in TX mode only?

Question

I have this wierd problem: I need to connect two sites linked with a 4-couple multimode cable.

At both end I installed HP Aruba 2530-8 switches with J4858D GBIC adapters.

The situation I'm now facing is that the link light comes up but the switches are unreachable.

Interface statistics for the GBIC interface show a lot of TX traffic with no RX traffic (Link status: UP and Port Enabled: Yes).

The first couple is alreay in use and working fine.

I tried all the other couples to no avail.

Any suggestion is appreciated.

Are you seeing a link light at both ends? Are the counters incrementing now or are they historic? Is spanning tree blocking the port on either end? Does the speed and duplex match on both ends? — user27899, Commented Jul 5, 2018 at 11:06
@KarlBillington The link light is on at both ends, the counters are incrementing, the spanning tree shows "Forwarding" but the edge type is identified as "Edge" (as if it was a PC). I also tried with a brand new GBIC. I did not try forcing the speed/duplex since it should be automatically recognized by the GBIC. — Alessandro Baldoni, Commented Jul 5, 2018 at 12:23
hmm, if spanning tree is showing Edge status, there can't be any BPDUs received or it would operate as a normal spanning tree port. Sounds like the fibre is not working in one direction. Have you tried new patch cables and a different fibre run? Could you post the following commands - show run interface <interface-number> , show interface <interface-number> and show spanning-tree <interface-number> for both ends of the link? — user27899, Commented Jul 5, 2018 at 12:40
Should the problem be in the switch itself? I put the GBIC I'm using on another switch (an HP 5130) and the link comes up readily showing the LLDP properties of the remote switch. I'm going to find another 2530 to repeat this test. — Alessandro Baldoni, Commented Jul 5, 2018 at 14:29

Alessandro Baldoni · Accepted Answer · 2018-07-11 10:11:36Z

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I changed the switch with another one (same brand, same model, same production batch) and now everything works.

answered Jul 11, 2018 at 10:11

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Commented Jul 11, 2018 at 13:04

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hamid bayat · Accepted Answer · 2018-07-07 08:36:18Z

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in both side you have TX and no RX? in both side links are up? if this situation is for one side, it means that one core of fiber cable has too much loss. a. try to clean it. b. change TX/RX of cable on both side. c. change the cable. d. change transceiver.
set ports to defaults (conf t# default interface g1/1/1)
first check CDP and then ping. (show CDP neighbor)
try auto negotiation off and on (on both side)

answered Jul 7, 2018 at 8:36

hamid bayat

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2 Answers 2