Issue with VLANs at Cisco 2960

[gshengel]

Hello there.

I have an issue with two VLANs from one of the providers.

Situation: I have 2 VLANs (2342 and 3557) that are coming from an internet service provider to my Cisco 2960 switch. Uplink port #1 is configured as a trunk. Port #2 configured for VLAN 3557, 14x ports ##11-24 for VLAN 2342.

I have a perfect connection to the link, provided by VLAN 3557 to port #2. But there is no connection to all 14 ports, configured for VLAN 2342. I had chat with the provider's technicians and they told me that could not see any MAC for equipment, connected to those ports (all ports are up with equipment plugged in). So, they are blaming me for the wrong config. And before starting blaming them back I need your advice.

Here is the related part of config:

!
vtp mode transparent
!
vlan 2342,3557
!
interface FastEthernet0/1
description Uplink_to_Provider
switchport mode trunk
!
interface FastEthernet0/2
description Internet
switchport access vlan 3557
!
interface FastEthernet0/11
description IPTV
switchport access vlan 2342
!
*
*
*
!
interface FastEthernet0/24
description IPTV
switchport access vlan 2342
!
end

Here is some additional information that could be helpful:

1. Mac Address Table
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/16
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/14
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/17
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/22
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/20
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/18
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/13
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/15

2342 xxxx.xxxx.xxxx DYNAMIC Fa0/12
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/19
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/24
2342 xxxx.xxxx.xxxx DYNAMIC Fa0/11
3557 xxxx.xxxx.xxxx DYNAMIC Fa0/1
3557 xxxx.xxxx.xxxx DYNAMIC Fa0/2
For some unknown reason, port #1 is shown as part of VLAN 3557 (but it is configured as a trunk at the config, provided above).

2. show vlan brief

1 default active Fa0/3, Fa0/4, Fa0/5, Fa0/6, Fa0/7, Fa0/8, Fa0/9, Fa0/10, Gi0/1, Gi0/2
*

*

*
2342 VLAN2342 active 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
3557 VLAN3557 active Fa0/2

Any suggestions?

Thanks in advance!

[balaji.bandi]

what is the reason for the port 1 to be trunk :

Try one of the config and let us know how that goes ?

interface FastEthernet0/1
description Uplink_to_Provider
switchport mode trunk

switchport trunk allowed vlan add 2342

or

interface FastEthernet0/1
description Uplink_to_Provider
switchport mode trunk

switchport trunk allowed vlan remove 3557

[Georg Pauwen · Accepted solution]

Hello,

my guess is that your ISP has (mis)configured their side as an access port in Vlan 3557 rather than a trunk port.

You can test this assumption by configuring the port as an access port in Vlan 3557:

interface FastEthernet0/1
description Uplink_to_Provider
switchport mode access
switchport access vlan 3557

and then as a access port in Vlan 2342:

interface FastEthernet0/1
description Uplink_to_Provider
switchport mode access
switchport access vlan 2342

If the access port 2342 does not work, you know that they need to configure their side port as a trunk.

[gshengel]

Gents,

Thanks for your response! This switch is located at the remote site 300+ km away from my current location and I have no remote access (due to the issues stated above). I will copy-paste both proposals and will arrange a trip there ASAP. I will let you know which solution did work as soon as will be back.

Thanks again!

[gshengel]

Finally, the issue had been fixed. As Georg Pauwen supposed above - ISP just incorrectly configured port at their side (access instead of trunk). Configuration changed, everything works fine.

Thanks for your support, guys. May the force be with you!