03-24-2015 01:51 PM - edited 03-07-2019 11:14 PM
I have been tasked with establishing communications from my Cisco 4510 R+E core switch via a new fiber run (MM, OM3, 945ft) to Cisco 2960X switch. I'm using pairs of new Cisco SPF-10G-SR's on either end of the fiber.
Before deploying the remote 2960X switch I tested the config's and all 2m fiber patch cables by simply plugging the remote 2960x switch to the 4510 switch. Once connected they immediately formed Trunk links. I further tested by adding a host pc to the remote 2960X switch and it pulled via DHCP a IP address from the correct VLAN. I was satisfied with those results.
I then deployed the 2960X to it's remote location and the results were much different. The 4510 fails to see any SFP connected to the remote end.
r 24 13:24:17: %SFF8472-5-THRESHOLD_VIOLATION: Te5/2: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
Mar 24 13:24:23: %SFF8472-5-THRESHOLD_VIOLATION: Te6/2: Rx power low alarm; Operating value: -40.0 dBm, Threshold value: -13.9 dBm.
I thought immediately I had physical layer with the run of fiber. I have had it tested and meets standards.
The 2960X also fails to detect the 4510 switch. Just for grins I had 'jumpered' fiber pairs 1 to 2 in the data center end and the 2960X logged this:
Mar 17 07:35:02: %LINK-3-UPDOWN: Interface TenGigabitEthernet1/0/1, changed state to up
Mar 17 07:35:02: %LINK-3-UPDOWN: Interface TenGigabitEthernet1/0/2, changed state to up
Mar 17 07:35:10: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to up
Mar 17 07:35:10: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/2, changed state to up
Mar 17 07:35:39: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan10, changed state to up
Mar 17 07:42:19: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan10, changed state to down
Mar 17 07:42:20: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to down
Mar 17 07:42:20: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/2, changed state to down
Mar 17 07:42:21: %LINK-3-UPDOWN: Interface TenGigabitEthernet1/0/1, changed state to down
Mar 17 07:42:21: %LINK-3-UPDOWN: Interface TenGigabitEthernet1/0/2, changed state to down
This tells me the long run of fiber is good.
In my thinking I have tested in steps, the physical layer from 4510 SFP to remote 2960X SFP's.
I have included the relevant config lines of both switches.
4510 uses etherchannel 10.
boot system flash bootflash:cat4500e-universal.SPA.03.04.04.SG.151-2.SG4.bin
interface Port-channel10
description "Uplink to IDF 'F'"
switchport
switchport trunk native vlan 10
switchport trunk allowed vlan 5,10,15
switchport mode trunk
!
interface TenGigabitEthernet5/2
description "Uplink to IDF 'F'"
switchport trunk native vlan 10
switchport trunk allowed vlan 5,10,15
switchport autostate exclude
switchport mode trunk
no keepalive
channel-protocol lacp
channel-group 10 mode active
!
interface TenGigabitEthernet5/3
!
interface TenGigabitEthernet5/4
!
interface TenGigabitEthernet6/2
description "Uplink to IDF 'F'"
switchport trunk native vlan 10
switchport trunk allowed vlan 5,10,15
switchport autostate exclude
switchport mode trunk
no keepalive
channel-protocol lacp
channel-group 10 mode active
************************************************
Config from 2960X switch,
Cisco IOS Software,(C2960X-UNIVERSALK9-M), Version 15.0(2)EX3
interface Port-channel2
switchport access vlan 10
switchport trunk native vlan 10
switchport trunk allowed vlan 5,10,15
switchport mode trunk
!
interface TenGigabitEthernet1/0/1
switchport access vlan 10
switchport trunk native vlan 10
switchport trunk allowed vlan 5,10,15
switchport mode trunk
channel-group 2 mode active
!
interface TenGigabitEthernet1/0/2
switchport access vlan 10
switchport trunk native vlan 10
switchport trunk allowed vlan 5,10,15
switchport mode trunk
channel-group 2 mode active
I don't know any debug commands to try since the 4510 is not even seeing the other end.
03-24-2015 09:50 PM
This issue could be caused by 2 things. Either your SFPs are under spec's or your long run Fiber has a higher loss than it should. Is the db loss on your fiber run within the thresholds of the SFP?
05-11-2015 10:34 AM
Thank you Andre for replying to my post. I have it resolved now. It was the physical layer. All that was needed was a pair reversal on one end of the fiber patch cable. I have had plenty of experience with ST fiber connections but was my first project with LC only fiber connections. With ST connections if it fails to link right up try to reverse the fiber pair. It never occurred to me reverse the LC fiber pair.
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