05-28-2007 08:31 AM - edited 03-05-2019 04:20 PM
hi! If i want to allow only vlan 100-105 to go through a trunk between 2 switches. Do i need to remove the existing vlan from the trunk first(default all vlan are allowed) and then add in vlan 100-105? or just issue the command "switchport trunk allowed vlan 100-105"? Please advise. Thanks.
05-28-2007 08:37 AM
You can only use" switchport trunk allowed vlan
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2960/12225see/cr/cli3.htm#wp1948736
HTH,please rate if it does.
-amit singh
05-28-2007 09:06 AM
hi! What's the function of a native vlan? Will there be any problem if both end of the switches have different native vlan number?
Thanks.
05-28-2007 09:09 AM
Native vlan is enabled on Cisco switches by default and Vlan1 is the native vlan. The native vlan is used to carry untagged frames across a trunk link.You will not be able to form a trunk if the native vlan is different on the trunk links. They have to be same on both the sides.
-amit singh
05-28-2007 04:22 PM
hi! Does that mean native vlan is used only in trunking? All the ports are in vlan1(native vlan) by default, right?
Any relationship between management vlan and native vlan? The default management vlan is also vlan1, right?
05-28-2007 08:39 AM
Hi Friend,
On IOS switches if you just allow vlans that will take care of your requirement and no need to specifically clear other vlans first
Switch#sh run int gig1/0/23
Building configuration...
Current configuration : 137 bytes
!
interface GigabitEthernet1/0/23
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 22-26
switchport mode trunk
end
Switch#sh int gig1/0/23 switchport
Ankur_Desk_Switch#sh int gig1/0/23 switchport
Name: Gi1/0/23
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)
Administrative Native VLAN tagging: enabled
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 Native VLAN tagging: enabled
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: 22-26 <<<---------
HTH
Ankur
*Pls rate all helpfull post
05-28-2007 10:21 PM
afaik, vlan 1 is management vlan and native vlan by default.
yes all the ports are in vlan 1 by default
in trunking if isl method is used then native vlan need not to be same.(and cisco s/w by default uses isl)
but with 802.1q trunking the native vlan packs as send untagged.so its a must that native vlan on both end be the same...
regards
arun:)
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