Point to point Fiber connection

[satya mothukuri]

Hi all,

  We have a P2P 100 Mb link between our Datacenters.  Connection is terminated on 2960 stack switch on both ends. The configuration on the switch is normal. Today the switch port has gone down. We tot its ISP problem, but after some time we have shut and no shut which made the connection up.

Now i want to know is this UDLD or other problem which caused the link down. There are no logs related to this.

Please suggest any config if you have

Config on switch#################

interface GigabitEthernet2/0/25
 switchport access vlan 45
 switchport mode access
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape 10 0 0 0
 queue-set 2
 priority-queue out
 mls qos trust dscp
 spanning-tree portfast
end

Logs#################

Aug 18 13:09:49.034: %LINK-5-CHANGED: Interface GigabitEthernet2/0/25, changed state to administratively down

Version#####

Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.0(2)EX3, RELEASE SOFTWARE (fc1)

System image file is "flash:/c2960x-universalk9-mz.150-2.EX3.bin"

Regards,

Satya.M

[Akash Agrawal]

Hi Satya,

Syslog from both sides devices during time of issue would help to check what triggered the link down.

Regards,

Akash

[satya mothukuri]

Akash you are right, but have removed syslog on that day for some server issue.

Let me know if you know any in general config for a P2P link with  fiber termination on switch.

Regards,

Satya.M

[Akash Agrawal]

Hi Satya,

So far it looks like that port went to errordisabled mode and that is why it was down and shut/no-shut helped to recover it. Since this fiber connectivity is provided by ISP and transmission is involved There could be below possible reasons when port may go to error disable state

- UDLD

- Link was flapping continuously

- Loopback error

There are other reasons also, you can refer below link

http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/69980-errdisable-recovery.html

Once link is down due to errdisable, to recover it you need to perform shut/no-shut even though root problem is resolved.  Or you should have errdisable recovery should be enabled.

cat6knative#show errdisable recovery
ErrDisable Reason    Timer Status
-----------------    --------------
udld                 Disabled
bpduguard            Disabled
security-violatio    Disabled
channel-misconfig    Disabled
pagp-flap            Disabled
dtp-flap             Disabled
link-flap            Disabled
l2ptguard            Disabled
psecure-violation    Disabled
gbic-invalid         Disabled
dhcp-rate-limit      Disabled
mac-limit            Disabled
unicast-flood        Disabled
arp-inspection       Disabled

Timer interval: 300 seconds

cat6knative(Config)#errdisable recovery cause bpduguard

cat6knative#show errdisable recovery
ErrDisable Reason    Timer Status
-----------------    --------------
udld                 Disabled
bpduguard            Enabled  <<<<<<<<<<<<<<<<
security-violatio    Disabled
channel-misconfig    Disabled
pagp-flap            Disabled
dtp-flap             Disabled
link-flap            Disabled
l2ptguard            Disabled
psecure-violation    Disabled
gbic-invalid         Disabled
dhcp-rate-limit      Disabled
mac-limit            Disabled
unicast-flood        Disabled
arp-inspection       Disabled

Timer interval: 300 seconds

cat6knative(Config)#errdisable recovery interval 400

Regards,

Akash

[paul driver]

Hello

do you have udld enabled?
what does the log buffer show?
do you have errdisable recovery enable for udld?

show udld intx/x
show interface x/x status
show interface status err-disabled
show logg

res

Paul
 

[satya mothukuri]

Hi Paul....tnx for your reply. Plz find the outputs.

sw#sh udld gigabitEthernet 2/0/25

Interface Gi2/0/25
---
Port enable administrative configuration setting: Follows device default
Port enable operational state: Disabled
Current bidirectional state: Unknown

sw#sh interfaces gigabitEthernet 2/0/25 status

Port      Name               Status       Vlan       Duplex  Speed Type
Gi2/0/25  ** P2P-BRDC-CHALFO connected    45         a-full a-1000 1000BaseSX SFP

sw#sh interfaces status err-disabled
sw#

Aug 18 10:48:59.079: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/0/25, changed state to down
Aug 18 10:49:00.079: %LINK-3-UPDOWN: Interface GigabitEthernet2/0/25, changed state to down

Regards,

Satya.M