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New Member

UDLD problem, goes in err-dis when it should'nt

I have a 3750 and 6509 connected with fiber. When i take no shut on the interface at the 3750 side, the port goes in err-disable. I have tried a new fiber, new SFP and also changed ports. But the problem is still there. Below is the config and som output.

When I remove the "udld port" from the interface on the 3750, the port becomes up and traffic flows as normal.

Why?

3750:

interface GigabitEthernet1/0/25

switchport trunk encapsulation dot1q

switchport trunk native vlan 998

switchport trunk allowed vlan 1-179,190-679,682-689,800-4094

switchport mode trunk

udld port

Interface Gi1/0/25

---

Port enable administrative configuration setting: Enabled

Port enable operational state: Enabled

Current bidirectional state: Unidirectional

Current operational state: Disabled port

Message interval: 7

Time out interval: 5

No neighbor cache information stored

Sep 4 17:08:58: %UDLD-6-UDLD_PORT_RESET: UDLD reset interface Gi1/0/25

Sep 4 17:08:58: %PM-4-ERR_RECOVER: Attempting to recover from udld err-disable state on Gi1/0/25

Sep 4 17:09:01: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/25, changed state to up

Sep 4 17:09:02: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/25, changed state to up

Sep 4 17:09:05: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi1/0/25, unidirectional link detected

Sep 4 17:09:05: %PM-4-ERR_DISABLE: udld error detected on Gi1/0/25, putting Gi1/0/25 in err-disable state

Sep 4 17:09:06: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/25, changed state to down

Sep 4 17:09:07: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/25, changed state to down

3750_sw#udld reset

1 ports shutdown by UDLD were reset.

3750_sw#sh udld gigabitEthernet 1/0/25

Interface Gi1/0/25

---

Port enable administrative configuration setting: Enabled

Port enable operational state: Enabled

Current bidirectional state: Neighbor's echo is empty

Current operational state: Detection

Message interval: 7

Time out interval: 5

Entry 1

---

Expiration time: 21

Device ID: 1

Current neighbor state: Neighbor's echo is empty

Device name: 015C738100

Port ID: Gi3/7

Neighbor echo empty

Message interval: 7

Time out interval: 5

CDP Device name: 6509_sw

3750_sw#sh udld gigabitEthernet 1/0/25

Interface Gi1/0/25

---

Port enable administrative configuration setting: Enabled

Port enable operational state: Enabled

Current bidirectional state: Neighbor's echo is empty

Current operational state: Detection

Message interval: 7

Time out interval: 5

Entry 1

---

Expiration time: 21

Device ID: 1

Current neighbor state: Unknown

Device name: 015C738100

Port ID: Gi3/7

Neighbor echo empty

Message interval: 7

Time out interval: 5

CDP Device name: 6509_sw

6500:

interface GigabitEthernet3/7

switchport

switchport trunk encapsulation dot1q

switchport trunk native vlan 998

switchport trunk allowed vlan 1-179,190-679,682-689,800-4094

switchport mode trunk

udld port

spanning-tree guard root

Interface Gi3/7

---

Port enable administrative configuration setting: Enabled

Port enable operational state: Enabled

Current bidirectional state: Unknown

Current operational state: Link down

Message interval: 7

Time out interval: 5

No neighbor cache information stored

Br

Geir

2 REPLIES
New Member

Re: UDLD problem, goes in err-dis when it should'nt

Problem solved. Native vlan 998 was not created at the 3750. When i did, the port resolved from err-disabled when I reset the udld.

3750 was in transparent mode.

Geir

Hall of Fame Super Silver

Re: UDLD problem, goes in err-dis when it should'nt

Hello Geir,

nice to hear that you solved this issue.

You have been kind to provide the root cause.

This makes this a complete story.

Best Regards

Giuseppe

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