08-20-2008 04:04 AM - edited 03-06-2019 12:54 AM
I have a Catalyst 3500XL ( WS-C3508G-XL) with 8 Giga interfaces and a Catalyst 3550 linked with a fiber, working ok.
Now i have replaced the C3550 for a C2960.
But I cant make the link up connecting the C2960 with the 3500XL.
I had to change the fiber to another 3500XL ( WS-C3548-XL ) in order to work.
Everytime I try to change from the C3548 to the C3508G the link do not work.
I dont know what it can be.
Here is the interfaces configuration.
For the 2960:
Current configuration : 86 bytes
!
interface GigabitEthernet0/1
description link L22SW-01
switchport mode trunk
end
For the C3508 ( the one that the link doesnt work)
Current configuration:
!
interface GigabitEthernet0/4
description Switch Botafogo 24
switchport trunk encapsulation dot1q
switchport mode trunk
end
for the C3548
Current configuration:
!
interface GigabitEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
end
08-20-2008 04:12 AM
A couple of things to try:
1. Have you tried explicitly setting the trunk encapsulation on the 2960 interface?
2. Try comparing the outputs of: sh int Gi0/X switchport to see if there's anything obviously different. Also look at sh int gi0/X controller
08-20-2008 04:58 AM
Branfarm1,
1- There is no explicity trunk encapsulation command in this ios version. Only works with the dot1q by default
2- I have made a compare with the commands sh int gig0/x switch port
Can you check in order to see if there is someting wrong:
From the 2960:
L24SW-02#sh interfaces gigabitEthernet 0/1 switchport
Name: Gi0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
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
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Appliance trust: none
From the C3508:
L22BB-01#sh int gigabitEthernet 0/4 switchport
Name: Gi0/4
Switchport: Enabled
Administrative mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: Disabled
Access Mode VLAN: 0 ((Inactive))
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: ALL
Trunking VLANs Active: 1,10-12,20,25,100-102,200,300,400-405,500,510,555,600,
700,900-908,914,920,922,923,939-969
Pruning VLANs Enabled: 2-1001
Priority for untagged frames: 0
Override vlan tag priority: FALSE
Voice VLAN: none
Appliance trust: none
From the C3548
L24SW-01#sh int gigabitEthernet 0/1 switchport
Name: Gi0/1
Switchport: Enabled
Administrative Mode: trunk
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Protected: false
Unknown unicast blocked: disabled
Unknown multicast blocked: disabled
Voice VLAN: none (Inactive)
Appliance trust: none
08-20-2008 05:20 AM
So when you say the link between the two switches isn't working does that mean that the trunk never actually forms and the link shows down on one side?
08-20-2008 05:44 AM
Exactly it is like there is no fiber connecting them.
It is equal as I remove the fiber.
08-20-2008 05:48 AM
Hmm... that's an interesting one. Have you started off with the most basic of basics - tried a different piece of fiber, different GBICS or SFP's, different slots?
08-20-2008 07:05 AM
Yes already tried this.
Replaced the Fiber patch cord, the gbic and changed the port, but no joy
08-20-2008 07:47 AM
Well, I wish I could be more help, but it sounds like we'll need to get someone with more technical troubleshooting skills involved. This is starting to appear like it's more than just a configuration issue.
On a related note, I've had this problem in the past with fiber connections between 4507's and 3020 Blade switches. I was never able to get the link to work though, so I had to switch it over to a copper connection. I'm interested to find out what the solution ends up being.
08-20-2008 07:59 AM
can you send me "sh vlan brief or show vlan" on the C3508
08-20-2008 08:09 AM
One thing to check on gig stuff is the flow control. I normally only have a issue between cisco and non cisco stuff.
If the ports are in a up status you may want to check and see if you see CDP neighbor or spanning tree active on vlan 1.
If these are up the next to check is for a VTP issue. When you force the ports to trunk you they will come up even if the VTP domain does not match but they will not exchange any vlan information.
08-20-2008 09:41 AM
Tdrais,
What does it mean if the one end of the link shows as down? That's the problem I had -- one end of the link showed up, while the other end showed down. I tried multiple cables, GBIC's, ports, etc.
08-20-2008 09:34 PM
Hi
It me have something to do with the
Administrative Native VLAN tagging: enabled
Settings on the 2960.
Try to change it to no native vlan tagging (default).
Willem
08-21-2008 01:02 AM
I have the same problem a year ago,
what i have did is specified the speed and the duplex on the interfaces. Although this would not required but helped me to bring the link up.
secondly try by removed the trunk configuration on each switch.
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