Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

Switch ports (layer-3) terminates Laser link flaps

Hi,

I have a Laser link between 2 buildings. The both ends of the link terminates on 4500 L3 switch ports.Both switches logs interface (both ends) flap atleast 3-4 times in a day, even when the Laser receival powers are good.

BGP is running acoss the link and once in 2-3 days the BGP takes few seconds hit. See below the switch port configs and suggest if you think anything need to be changed to avoid this. I do not see any major L1 errors to doubt on the cabling.

BLDGA-4510-S1#sh runn int gig 3/4

Building configuration...

Current configuration : 298 bytes

!

interface GigabitEthernet3/4

description :LOS/Laser link to BLDGB

no switchport

dampening 30 2000 200 20 restart

bandwidth 900000

ip address 10.40.2.1 255.255.255.252

logging event link-status

delay 15

keepalive 4

udld port aggressive

no cdp enable

end

*****************************

BLDGB-4510-S1#sh run int gig 4/3

Building configuration...

Current configuration : 283 bytes

!

interface GigabitEthernet4/3

description :LASER/LOS Link to BLDGA

no switchport

dampening 30 2000 200 20 restart

ip address 10.40.2.2 255.255.255.252

logging event link-status

delay 15

keepalive 4

udld port aggressive

no cdp enable

end

Thank you

MS

1 REPLY

Re: Switch ports (layer-3) terminates Laser link flaps

Hi MS,

Your interface config should be fine, the problem that you describe is unlikely to be caused by configuration issues.

A few thing came up when reading this:

1: Be aware that the laser's output level can also be too high which would be causing bit errors due to oversteered inputs. You could try to use a set of dampers to reduce the input levels.

2: Please check that the fiber cable is indeed single mode and is in accordance with the specs of the GBIC or SFP.

3: Verify that your fiber patchcables have the same specs as the fiber link.

regards,

Leo

204
Views
0
Helpful
1
Replies
CreatePlease login to create content