The different of DEFAULT VLAN AND NATIVE VLAN
Initially, in a new switch like WS-C2960-24TC-L
Default VLAN=Native VLAN=VLAN 1
But, as controlling traffic like CDP(Cisco Discovery Protocol: To find out connected devices), VTP, PAgP traverse over VLAN 1
Cisco recommends to change Native VLAN from VLAN 1 to other VLAN
VLAN 1 cannot be shut down in any case, as it carries controlling traffic
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NATIVE VLAN CONCEPT
POINTS TO BE NOTED
- Native VLAN traffic traverse untagged, there is no tagging
- Native VLAN exist in case of encapsulation type 802.1Q(802.1Q supports untagged traffic, ISL do not support untagged traffic)
How to modify Native VLAN from VLAN 1 to any other VLAN
Switch(config-if)#switchport trunk native vlan vlan-id
No. of Native VLAN possible=No. of trunk ports
Example: Why we require more than one Native VLAN in a switch?
Switches Connected : Network 1——–SA(F0/2) (F0/1)SB—–Network 2
Network 1 and 2 has to be connected
At SA, again, we have only one Native VLAN, VLAN 20 : connected to network 1
At SB, we have only one Native VLAN, VLAN 10 : connected to network 2
Both SA and SB have different Native VLAN’s
To connect SA and SB, both should have same Native VLAN
So, either at SA and SB, One more Native VLAN is require
Case 1:
At SA,we create One more Native VLAN for trunk port F0/2
Switch(config)#conf t
Switch(config)#int F0/2
Switch(config-if)#switchport trunk native vlan 2
Case 2:
At SB,we create One more Native VLAN for trunk port F0/1
Switch(config)#conf t
Switch(config)#int F0/1
Switch(config-if)#switchport trunk native vlan 10
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