01-06-2013 12:46 PM - edited 03-07-2019 10:55 AM
01-07-2013 04:19 AM
Cisco switches always have VLAN 1 as the default VLAN, which is needed for many protocol communication between switches like spanning-tree protocol for instance.
You can't change or even delete the default VLAN, it is mandatory.
The native VLAN is the only VLAN which is not tagged in a trunk, in other words, native VLAN frames are transmitted unchanged.
Per default the native VLAN is VLAN 1 but you can change that:
#show interface Fa0/8 trunk
Port Mode Encapsulation Status Native vlan
Fa0/8 on 802.1q other 1
(config-if)#switchport trunk native vlan 2
(config-if)#do show interface f0/8 trunk
Port Mode Encapsulation Status Native vlan
Fa0/8 on 802.1q other 2
The default VLAN is still VLAN 1.
#show vlan id 1
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/8, Gi0/1
HTH
Rolf
01-10-2013 04:47 AM
HI Pradeep,
This has already been discussed amny times:
As for answering the initial question, let's make thing simple:
Let's get into some details now:
The error message can be seen in multiple situations:
Regards
please rate if it helps.
03-22-2018 10:54 AM
Hi Sandeep,
Could you please give some more details on the scenario with native VLAN mismatch and the CDP warning?
How could this produce any kind of loops?
03-23-2018 09:43 AM
Natative VLAN is used for untagged traffic. If native VLAN differe between switches then it wont break the trunk rather CDP throws error message. for example you connect switch A to switch B, their native VLAN must be VLAN x on both switches.But if any Switch A has VAN x and Switch B has VLAN Y then you get error message.
By default VLAN 1 i.e default VLAN is used as native VLAN.
03-23-2018 11:46 AM
Thank you for the feedback sathvik. However, this does not answer my question. My question is how a L2 loop can happen while using CDP and different native VLANs across switches. An example or maybe a graph would certainly help a lot.
Thank you
03-23-2018 12:37 PM
12-23-2018 08:10 PM
12-27-2018 11:39 AM
03-05-2019 11:51 AM - edited 03-05-2019 11:55 AM
@Ouelmath wrote:
Thx Sandeep Choudhary for the explaination. I understand the theory. But I still have a hard time understanding the benefits of the Native Vlan. In what scenario will I want to have devices connected in an acces port x with vlan y that his my Native Vlan....
Thx
Here is a CONCISE and UP TO THE POINT explanation and I quote:-
Default VLAN: This can refer to one of two types. Typically, the default VLAN refers to the one that all of the ports on a device belong to when it is switched on. On most switches, this default is VLAN 1 and should be changed for security reasons. Some network managers may use the term “default VLAN” to refer to a VLAN to which all ports are assigned when they’re not being used.
Native VLAN: The native VLAN is the one into which untagged traffic will be put when it’s received on a trunk port. This makes it possible for your VLAN to support legacy devices or devices that don’t tag their traffic like some wireless access points and simply network attached devices.
Source:
10-02-2020 07:05 AM
THIS answer actually answers the question for anyone confused by how the most upvoted answer.
04-04-2020 01:58 PM
Very helpful definition. Thank you, Sandeep.
07-30-2024 03:55 PM
can you please elaborate below point, I just want to know more about L2 loop detection out of misconfiguration:
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide