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New Member

Fa0/2 port doesn't show up on show vlan. VTP/port assignment question

Hi, sorry if this is a stupid question:

In my cat 2900XL, I configure both fa0/1 and fa0/2 as 'switchport mode trunk', dot1 encapsulation.

I created VLAN1 and VLAN2. I want to have VLAN1 associated with fa0/1 (what it is by default). I want to VLAN2 associated with fa0/2.

I do 'show vlan' and the fa0/2 doesn't appear. What am I missing ?

Please find attached output.

My goal is to configure the scenario outlined on http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00800ae96a.shtml

1 ACCEPTED SOLUTION

Accepted Solutions
Purple

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

I think you are getting hungup on a idea that the vlan is not showing up on a particular port , or correct me if I am wrong . The show vlan command only shows "access ports" and the interfaces they are associated with , if the port f0/1 or f0/2 is a "active" trunk it will "not" show up with this command , this is normal . If you look at your original post port f0/1 does not show up in vlan 1 either , this is also normal because the port is a trunk . As long as the trunk is up and active and you have the vlans allowed that you want to use that is all that matters , on newer IOS switches this can be verified with the "show int trunk" command , though I am not sure if this command works on the old 2924's ,have never tried trunking one of those old switches . Also you seem to be trying to run client /server for vtp , make sure you don't have another switch as a server as you could be getting conflicting vlan information if you are making changes the 2924 switch and you insert that back into the network and the vtp revision numbers are not the same . The server using the highest vtp revision numbers propagates the vtp info into the network . You do not have to have port f0/2 assigned to vlan 2 if the port is a trunk , by default the native vlan will then be vlan 1 which only means if the trunk goes down it will be in vlan 1 , as long as vlan 2 is allowed across that trunk everything should be fine . Also the switchport trunk allowed command has nothing to do with the "show vlan " command as stated above , use the show interface trunk command to verify the trunk and allowed vlans on the trunk .

16 REPLIES
Silver

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Hi ,

please include switchport access vlan2 on f0/2 and check it.If you are not specifying any vlan on interface then it automatically belongs to vlan1.

Thanks,

satish

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Before I attempted that. I just did it again and 'show vlan' continues to show VLAN2 without any port associated with it in spite of the command. My running-config now looks like:

...

interface FastEthernet0/2

switchport access vlan 2

switchport trunk encapsulation dot1q

switchport mode trunk

!

interface FastEthernet0/3

Silver

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Hi ,

sorry for the mistake..Please remover switchport access valan 2 and add the follwoing command int f0/2.

switchport trunk allowed vlan 2.The following link has the config example.

http://www2.fiit.stuba.sk/~grellneth/ps2-ZS2006/29xx_using_CLI.pdf

The following is the example for trunk link.

(config)#interface gigabitethernet 0/1

Access_1 (config-if)#switchport mode trunk

Access_1 (config-if)#switchport trunk encapsulation dot1q

Access_1 (config-if)#switchport trunk allowed vlan add 5,8,10

Access_1 (config-if)#end

Hope it helps you.

Thanks,

satish

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Earlier I tried 'switchport trunk allowed vlan 2' as well. It didn't work.

I've executed 'switchport trunk allowed vlan add 2' like you did above, and problem persists. I already deleted vlan.dat, reloaded, and I again 'show vlan' shows VLAN2 is not associated with fa0/2. It is strange.

Also, I notice that I issue 'switchport trunk allowed vlan', I do 'wri mem' but show running-config doesn't display the commands...

interface FastEthernet0/1

switchport trunk encapsulation dot1q

switchport mode trunk

!

interface FastEthernet0/2

switchport trunk encapsulation dot1q

switchport mode trunk

(...)

Switch#show vlan

VLAN Name Status Ports

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

1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6,

Fa0/7, Fa0/8, Fa0/9, Fa0/10,

Fa0/11, Fa0/12

2 VLAN0002 active

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

Silver

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Hi ,

configure the switch like this .

interface fastethernet0/1

switchport mode trunk

!--- If you have configured 802.1Q,

!--- you instead see this output

!--- under interface fastethernet0/1:

!--- interface fastethernet0/1

!--- switchport trunk encapsulation dot1q

!--- switchport mode trunk

interface fastethernet0/2

switchport access vlan 2

!

interface fastethernet0/3

!

interface fastethernet0/4

!

check the output of sh int f0/1 and should be like this.

show interfaces fastethernet 0/1 switchport

Name: Fa0/1

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: 1,2

Pruning VLANs Enabled: 2-1001

Priority for untagged frames: 0

Override vlan tag priority: FALSE

Voice VLAN: none

Appliance trust: none

Self Loopback: No

and check the output of vlan and should be like

show vlan

VLAN Name Status Ports

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

1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6,

Fa0/7, Fa0/8, Fa0/9, Fa0/10,

Fa0/11, Fa0/12, Fa0/13, Fa0/14,

Fa0/15, Fa0/16, Fa0/17, Fa0/18,

Fa0/19, Fa0/20, Fa0/21, Fa0/22,

Fa0/23, Fa0/24, Gi0/1, Gi0/2

2 VLAN0002 active Fa0/2

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

I think after config. the switch you can see f0/2 in sh vlan .

check out the below link.

http://www.cisco.com/univercd/cc/td/doc/product/lan/c2900xl/29_35xu/scg/kivlan.htm#xtocid2442340

Thanks,

satish

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

I got same output than yours, but in this case, fa0/2 is not doing dot1q trunking, it is just working as an access port, correct ? If you don't mind to clarify this, on the the link below, I understand that both CatalystD and CatalystR switches ports /1 and /2 are configured for trunking. I am confused. I really thought that if I do 'switchport access vlan 2', that would be simply an access port, and not a trunk port. I still don't understand why the command 'switchport trunk allowed vlan' is not making vlan 2 be applied to fa0/2 trunking port...

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00800ae96a.shtml

Silver

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Hi ,

Yes , you are correct.If any interface is not doing trunking then it works as access point.

And a trunk port can become a member of a VLAN if the VLAN is enabled, if VTP knows of the VLAN, and if the VLAN is in the allowed list for the port. When VTP detects a newly enabled VLAN and the VLAN is in the allowed list for a trunk port, the trunk port automatically becomes a member of the enabled VLAN. When VTP detects a new VLAN and the VLAN is not in the allowed list for a trunk port, the trunk port does not become a member of the new VLAN.

Have you configured VTP on the switch ?

Can you configure the command ""switchport trunk allowed vlan remove 3-1001 on f0/2 and check it.

Thanks,

satish

Purple

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Satish is correct , you had it all backward , by default all vlans are allowed across the trunk you would have to remove all the vlans you do not want running across the trunk with the switchport trunk allowed vlan remove " command .

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

The switch is configured as a vtp server, domain = TEST.

After doing 'switchport trunk allowed vlan remove 3-1001' on fa0/2 I see fa0/2 associated with VLAN2 - as long as I keep the 'switchport access vlan 2' command on fa0/2. Should I keep this command there ? I remove the access vlan 2 command, then fa0/2 is not associated with VLAN2 anymore. The problem is that fa0/2 is not an dot1q trunk. Honestly I am confused.

Do you think I understand this right:

I want VLAN1 on fa0/1 setup as dot1q trunk.

I want VLAN2 on fa0/2 setup as dot1q trunk.

The configuration below still does not associated fa0/2 with VLAN 2.

interface FastEthernet0/1

switchport trunk allowed vlan 1,3-1005

switchport mode trunk

!

interface FastEthernet0/2

switchport trunk encapsulation dot1q

switchport trunk allowed vlan 1,2,1002-1005

switchport mode trunk

!

VLAN Name Status Ports

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

1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6,

Fa0/7, Fa0/8, Fa0/9, Fa0/10,

Fa0/11, Fa0/12

2 VLAN0002 active Fa0/2

1002 fddi-default active

1003 token-ring-default active

1004 fddinet-default active

1005 trnet-default active

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

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

1 enet 100001 1500 - - - - - 1002 1003

2 enet 100002 1500 - - - - - 0 0

1002 fddi 101002 1500 - - - - - 1 1003

1003 tr 101003 1500 1005 0 - - srb 1 1002

1004 fdnet 101004 1500 - - 1 ibm - 0 0

1005 trnet 101005 1500 - - 1 ibm - 0 0

Switch#

Switch#

Switch#show int fa0/2 switchport

Name: Fa0/2

Switchport: Enabled

Administrative mode: static access

Operational Mode: static access

Administrative Trunking Encapsulation: isl

Operational Trunking Encapsulation: isl

Negotiation of Trunking: Disabled

Access Mode VLAN: 2 (VLAN0002)

Trunking Native Mode VLAN: 1 (default)

Trunking VLANs Enabled: NONE

Pruning VLANs Enabled: NONE

Priority for untagged frames: 0

Override vlan tag priority: FALSE

Voice VLAN: none

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

If I understand, you want VLAN 1 over Trunk 1 and VLAN 2 sent over Trunk 2. Try this config,this will allow trunk failover.

!

interface fa0/1

switchport trunk encap dot1q

switchport mode trunk

switchport nonegotiate

switchport trunk allowed vlan all

spanning-tree vlan 1 cost 9

!

interface fa0/2

switchport trunk encap dot1q

switchport mode trunk

switchport nonegotiate

switchport trunk allowed vlan all

spanning-tree vlan 2 cost 9

!

This will leave a default cost of 19 on Fa0/1 for VLAN 2 & Fa0/2 for VLAN 1. It is showing your operational trunking mode as ISL which definately says something isn't right so be sure and issue "switchport nonegotiate".

Let me know if it helps!

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Hi Adam, correct I am trying to do trunk failover.

I am using 2900XL and when I did the 'switchport nonegotiate' that was not accepted. Just to let you know I am doing this disconnected from Switch2 just to make sure.

I do 'show vlan' and behavior is the same. Port fa0/2 is not associated with VLAN. I did exactly the commands you pasted above. Any ideas ?

interface FastEthernet0/1

switchport trunk encapsulation dot1q

switchport mode trunk

spanning-tree vlan 1 cost 9

!

interface FastEthernet0/2

switchport trunk encapsulation dot1q

switchport mode trunk

spanning-tree vlan 2 cost 9

!

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

I tried the commands on a 3550 instead; same behavior. I do show vlan and fa0/2 is not related to vlan 2. Weird.

hostname Switch

!

!

ip subnet-zero

!

!

spanning-tree mode pvst

spanning-tree extend system-id

!

!

interface FastEthernet0/1

switchport trunk encapsulation dot1q

switchport mode trunk

switchport nonegotiate

no ip address

spanning-tree vlan 1 cost 9

!

interface FastEthernet0/2

switchport trunk encapsulation dot1q

switchport mode trunk

switchport nonegotiate

no ip address

spanning-tree vlan 2 cost 9

!

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Can you reload both switches then paste the following output from both switches for me?

"wr t", "show interface trunk" & "show vlan brief"

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

Here.

Purple

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

I think you are getting hungup on a idea that the vlan is not showing up on a particular port , or correct me if I am wrong . The show vlan command only shows "access ports" and the interfaces they are associated with , if the port f0/1 or f0/2 is a "active" trunk it will "not" show up with this command , this is normal . If you look at your original post port f0/1 does not show up in vlan 1 either , this is also normal because the port is a trunk . As long as the trunk is up and active and you have the vlans allowed that you want to use that is all that matters , on newer IOS switches this can be verified with the "show int trunk" command , though I am not sure if this command works on the old 2924's ,have never tried trunking one of those old switches . Also you seem to be trying to run client /server for vtp , make sure you don't have another switch as a server as you could be getting conflicting vlan information if you are making changes the 2924 switch and you insert that back into the network and the vtp revision numbers are not the same . The server using the highest vtp revision numbers propagates the vtp info into the network . You do not have to have port f0/2 assigned to vlan 2 if the port is a trunk , by default the native vlan will then be vlan 1 which only means if the trunk goes down it will be in vlan 1 , as long as vlan 2 is allowed across that trunk everything should be fine . Also the switchport trunk allowed command has nothing to do with the "show vlan " command as stated above , use the show interface trunk command to verify the trunk and allowed vlans on the trunk .

New Member

Re: Fa0/2 port doesn't show up on show vlan. VTP/port assignment

That makes sense. 'show int trunk' doesn't work on my 2900XL, but I do this on the 3550 when interfaces are up and now I am getting this right. Thanks a lot !

That explains.

Switch#show int trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Fa0/2 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Fa0/2 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1-2

Fa0/2 1-2

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 none

Fa0/2 none

Switch#show vlan

VLAN Name Status Ports

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

1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6

Fa0/7, Fa0/8, Fa0/9, Fa0/10

Fa0/11, Fa0/12, Fa0/13, Fa0/14

Fa0/15, Fa0/16, Fa0/17, Fa0/18

Fa0/19, Fa0/20, Fa0/21, Fa0/22

Fa0/23, Fa0/24, Gi0/1, Gi0/2

2 VLAN0002 active

1002 fddi-default act/unsup

1003 token-ring-default act/unsup

1004 fddinet-default act/unsup

1005 trnet-default act/unsup

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

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

1 enet 100001 1500 - - - - - 0 0

2 enet 100002 1500 - - - - - 0 0

1002 fddi 101002 1500 - - - - - 0 0

1003 tr 101003 1500 - - - - - 0 0

1004 fdnet 101004 1500 - - - ieee - 0 0

1005 trnet 101005 1500 - - - ibm -

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