Trunking between 2 3550's

Guys,

I am trying to set up a trunk link between 2 3550 switches but cannot get the trunk link to form. I am connecting port f0/1 on the access switch to port f0/1 on the distribution switch. I have run the following commands under f0/1 on each switch:

interface FastEthernet0/1
switchport trunk encapsulation dot1q
switchport trunk native vlan 99
switchport mode trunk
switchport nonegotiate
logging event trunk-status
no shut

The output from sh int f0/1 switchport on both switches is as follows:

Access Switch

Name: Fa0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: down
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 99 (Inactive)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled

Distribution Switch

Name: Fa0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: down
Administrative Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 99 (Inactive)
Administrative Native VLAN tagging: enabled
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk Native VLAN tagging: enabled
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk associations: none
Administrative private-vlan trunk mappings: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
--More--

Notce that the operational Mode is DOWN. I have tried lots of different things but cannot get this trunk to form. I will be eternally grateful to anyone who cna help.

Thanks a million
Damien

Find more posts tagged with

SAVE $250 on Your CISCO Boot Camp — Use Code "EXAM26"

Exclusively for TechExams members for Infosec Boot Camps starting before April 30, 2026

View CISCO Boot Camps

Comments

wastedtime

You may want to make sure the cable is a crossover cable and double check there isn't a problem with the cable.

accely

wastedtime wrote: »

You may want to make sure the cable is a crossover cable and double check there isn't a problem with the cable.

I agree here. I've mistakenly had a ST cable plugged many times!

Make sure it's a cross over

Damienm30

Guys,

Thank you so much for saving me! I have spent some much time inspecting configs and reading Cisco docs that I overlooked the cabling. I am indeed using the wrong cable. dooooh!! Guess I learned lots about Trunking as a result. Thanks again for the prompt replies.

Damien

sides14

I always use different color cables to prevent this type of situation.

wastedtime

I was figuring that most people now a day’s use auto sensing mdi/mdi-x devices that they sometimes forget when a device isn't. I think I still got a switch (switching hub I believe is what they called it) somewhere that has a dedicated uplink port.