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VLAN not trunking between cat2900xl and 2950

Strange behaviour.

I have a cat2900xl and a 2950.

Just set VTP on both.

Interface are trunked in 802.1q on both (explicitly set on 2900xl, since by default it uses ISL).

Native VLAN is 1 on both.

Create VLANs on 2950 (which happens to be the VTP server), and they're connectly seen on the 2900xl.

Set VTP version 2, and both run in v2-mode.

Set pruning, and both set pruning.

create vlan4, and it's showed on both.

set an access port on vlan 4 on both, and traffic is not forwarded.

("show vlan" on 2900xl correctly shows the interface associated to vlan4).

notably, vlan4 is pruned on 2950 uplink interface (show interface trunk).

any hint?

TIA

Ivan

21 REPLIES

Re: VLAN not trunking between cat2900xl and 2950

can you post your config with "show interface trunk", "show vlan" and "show spanning-tree vlan 4 summ".

New Member

Re: VLAN not trunking between cat2900xl and 2950

sorry for the delay (being GMT+1, whole weekend passed).

neither "show interface trunk" nor "show spanning-tree vlan 4 summ" is supported on cat2900xl. Including "show spanning-tree vlan 4", hoping this may suffice.

Ivan

Re: VLAN not trunking between cat2900xl and 2950

Hi Ivan,

Can you make sure all related ports are in up/up state and capture "show spanning-tree vlan 4 detail" on both switches and "show interface trunk" on 2950?

Please post the related configuration as well, such as VTP config and port/trunk config.

New Member

Re: VLAN not trunking between cat2900xl and 2950

I cannot run right now, since, due to service delivery, I have to move all devices currently running in vlan 4 into 2950.

Gonna wait till tomorrow, so I can find a suitable remote machines (it's a couple of miles away from here) connected to 2900xl, so I can move it to vlan 4, just to see what's changing, and give you the relevant show's output.

Re: VLAN not trunking between cat2900xl and 2950

VTP prunning eleminate unneccessary broadcast requests from a Switch.

You have VTP configured, what is the VTP mode on both Switches? pls post sh int trunk from both?

HTH

Mohamed

New Member

Re: VLAN not trunking between cat2900xl and 2950

show int trunk does not work on c2900xl.

For the output, see the attachment above

Hall of Fame Super Gold

Re: VLAN not trunking between cat2900xl and 2950

"sh interface status" will work.

New Member

Re: VLAN not trunking between cat2900xl and 2950

you're right.

r-mi-ds69#sh int status

Port Name Status Vlan Duplex Speed Type

------- ------------------ ------------ -------- ------ ------- ----

Fa0/22 r-mi-ds70 f0/1 connected trunk A-Full A-100 100BaseTX/FX

New Member

Re: VLAN not trunking between cat2900xl and 2950

VTP is server on 2950 and client on 2900xl

New Member

Re: VLAN not trunking between cat2900xl and 2950

another info:

2950 is running rapid-pvst+, meanwhile 2900xl is running vanillca pvst.

This never gave a problem, since usually the rapid downscales the port to shared

(right now trunk port is seen as "P2p Peer(STP)")

Purple

Re: VLAN not trunking between cat2900xl and 2950

Can you post the trunk setup info for the 2900xl on the connecting port? If you can't ping between them then the trunk isn't working right.

Hall of Fame Super Gold

Re: VLAN not trunking between cat2900xl and 2950

Can you post the config for both the 2900XL and 2950 trunk ports?

New Member

Re: VLAN not trunking between cat2900xl and 2950

sorry for the delay.

here they are.

cat2900xl#sh run int f0/22

Building configuration...

Current configuration:

!

interface FastEthernet0/22

description cat2950 f0/1

switchport trunk encapsulation dot1q

switchport mode trunk

end

cat2950#sh run int f0/1

Building configuration...

Current configuration : 85 bytes

!

interface FastEthernet0/1

description cat2900xl f0/22

switchport mode trunk

end

Hall of Fame Super Gold

Re: VLAN not trunking between cat2900xl and 2950

What VLAN IP Address on the switches are you trying to ping? Is this enabled? (Note: You can only enable ONE VLAN in the 2900/3500XL and 2950).

On the 2950, can you type and post the following commands:

sh int f0/1 status

sh int trunk

sh int f0/1 switchport

On the 2900, can you type and post the following commands:

sh int f0/22 status

sh int f0/22 capab

New Member

Re: VLAN not trunking between cat2900xl and 2950

cat2950:

cat2950#sh int f0/1 status

Port Name Status Vlan Duplex Speed Type

Fa0/1 cat2900xl f0/22 connected trunk a-full a-100 10/100BaseTX

cat2950#sh int f0/1 trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1-4

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1

cat2950#sh int f0/1 switchport

Name: Fa0/1

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)

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

Appliance trust: none

cat2900xl (capability is not supported):

cat2900xl#sh int f0/22 status

Port Name Status Vlan Duplex Speed Type

------- ------------------ ------------ -------- ------ ------- ----

Fa0/22 cat2950 f0/1 connected trunk A-Full A-100 100BaseTX/FX

New Member

Re: VLAN not trunking between cat2900xl and 2950

cat2950:

cat2950#sh int f0/1 status

Port Name Status Vlan Duplex Speed Type

Fa0/1 cat2900xl f0/22 connected trunk a-full a-100 10/100BaseTX

cat2950#sh int f0/1 trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1-4

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1

cat2950#sh int f0/1 switchport

Name: Fa0/1

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)

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

Appliance trust: none

cat2900xl (capability is not supported):

cat2900xl#sh int f0/22 status

Port Name Status Vlan Duplex Speed Type

------- ------------------ ------------ -------- ------ ------- ----

Fa0/22 cat2950 f0/1 connected trunk A-Full A-100 100BaseTX/FX

New Member

Re: VLAN not trunking between cat2900xl and 2950

I'm not trying to ping an IP on the switch itself.

Instead, i'm trying to ping a device with a static ip address which resides on Vlan4.

New Member

Re: VLAN not trunking between cat2900xl and 2950

I'm not trying to ping an IP on the switch itself.

Instead, i'm trying to ping a device with a static ip address which resides on Vlan4.

Re: VLAN not trunking between cat2900xl and 2950

I asked you before to capture "show int trunk" and "show spanning-tree vlan 4" when you have access port in vlan 4 on both switch is up/up.

I am not sure when you captured the following output. But I did not see vlan 4 is listed under "Port Vlans in spanning tree forwarding state and not pruned"

cat2950#sh int f0/1 trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1-4

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1 <<<<<<

New Member

Re: VLAN not trunking between cat2900xl and 2950

That's exactly one of the sympthoms I outlined in the first place.

New Member

Re: VLAN not trunking between cat2900xl and 2950

SOLVED.

It turned out to be a problem with a misconfiguration.

I created and deleted by accident an "interface vlan4".

As long as this ghost configuration remained (status "deleted"), vlan did not work.

I was able to reboot the switch right now (maintenance window on application servers).

Since the interface vlan4 is gone, everything at L2 works as expected.

thanks everybody for the hints.

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