Canobeam free space optics configuration for connection to Cisco Catalyst 3560

20 pts.
Cisco Catalyst
I am having trouble with the Gigabit interface on a Cisco Catalyst 3560 that is connected to a Canobeam FSO device.  The problem is that the gig interface on the switch goes into error disable mode from time to time which takes down the link between two of our medical facilities.  The error disable message is a link-flap error.  I am familiar with the possible causes on the Catalyst side of the connection but would also like to know more about the Canobeam and if there are any possible settings or configuration issues.  I am fairly inexperience with the FSO device and I am seeking suggestions and info for troubleshooting the Canobeam. I appreciate any assistance. Thanks.

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Cisco Switch “errdisable” and Wireless Link implementation Issue

Problem: Wireless solutions can experience momentary loss of link due to precipitation bursts, birds, etc. that may last only a fraction of a second. Ordinarily, this is not a problem as any failed Ethernet frames caught in that moment are just retransmitted. A CRC error may or may not be registered in a management log.

Cisco switches have a feature, “errdisable”, which is intended to place a port into a disabled state in the event that port experiences a physical disruption.

The issue that arises with any wireless link is that there will be physical disruptions, although normally brief and transparent to user experience.

This is not a problem unless the port is thereby disabled by Cisco “errdisable”. In this case, the link will be downed due to disablement of the wireless equipment’s Cisco port by the switch’s “errdisable”.

To mitigate this potential issue, the following is strongly recommended on all Cisco switches:

Configure the Cisco device to not enter “error-disable state” as follows:

1.) # show errdisable detect (the ‘show’ command shows how errdisable is currently set.)

2.) (config)# no errdisable detect cause all (the ‘no’ command shuts off all forms of errdisable.)

3.) You may need to do a reset on the Cisco’s wireless device port both sides to obtain link

Alternatively, for link down following an “errdisable” you will need to reset the Cisco switch ports

Discuss This Question: 2  Replies

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  • BlankReg
    Rather than fix the symptom, you should really look to cure the cause. Check the alignment of the Canobeam, and make sure that both units are mounted on a 100% stable platform. Also check that there is NOTHING that can get in the way of the beam between the units. If necessary, sit up near the units (at both ends) and wait for that bird to sit right in front of it, then fix some plastic anti-bird spikes in the right place ! These units are usually quite reliable, if maintained correctly, so check these before masking the problem on the Cisco switch.
    12,325 pointsBadges:
  • JonathanSpitfire
    I'll agree with Pschoon and respectfully (partially) disagree with BlankReg on this one. I'll agree that link alignment & stability of the mount ing needs to be verified and that there are no avoidable line of sight disruptions, however you cannot control the weather. We have CanoBeam links in place (connected to Cisco Catalyst 3560 fiber SFPs directly) and they are disrupted by very dense fog. We happen to experience this several times per year in the spring and fall. Because the fog is moving and does not have a uniform density, it is not unusual for that to cause the Cisco switchport to go into err-disable. The only fix, to my knowledge, is to compensate for this within the Cisco configuration described in Pschoon's post.
    10 pointsBadges:

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