Configure SW1 interface gi0/0 as a manual trunk port using vlan 99 as the native VLAN and using 802.1Q trunking protocol instead of ISL protocol
Configure SW2 interface gi0/0 as a manual trunk port using vlan 99 as the native VLAN and using 802.1Q trunking protocol instead of ISL protocol
Verify trunking between the two switches
Get a detailed view of the trunking configuration on a specific interface
IMPLEMENTATION
01.Switch1(config)# vlan 99
Switch1(config-vlan) name NATIVE_VLAN
Switch1(config)# interface gi0/0
Switch1(config)# switchport trunk encapsulation dot1q
Switch1(config-if)# switchport mode trunk
Switch1(config-if)# switchport trunk native vlan 99
02.Switch2(config)# vlan 99
Switch2(config-vlan) name NATIVE_VLAN
Switch2(config)# interface gi0/0
Switch2(config)# switchport trunk encapsulation dot1q
Switch2(config-if)# switchport mode trunk
Switch2(config-if)# switchport trunk native vlan 99
03.Switch1# show interfaces trunk
Switch2# show interfaces trunk
04.Switch1# show interface g0/0 switchport
Switch2# show interface g0/0 switchport
* VLAN 99 must be created else it will state
"Trunking Native Mode VLAN: 99 (Inactive)"
* both interfaces have to match or the trunk link will not form
properly. Once the trunk link is formed, all VLAN traffic can
pass over the trunk link
DYNAMIC/ACTIVE TRUNKING
Dynamic/Active is where a DTP mode actively initiates & responds to DTP messages
PROCEDURE
Configure SW1 interface gi0/0 to actively initiate trunking using vlan 99 as the native VLAN and using 802.1Q trunking protocol instead of ISL protocol
Configure SW2 interface gi0/0 to actively initiate trunking using vlan 99 as the native VLAN and using 802.1Q trunking protocol instead of ISL protocol
Verify trunking between the two switches
Get a detailed view of the trunking configuration on a specific interface
Troubleshoot and verify DTP
IMPLEMENTATION
01.Switch1(config)# vlan 99
Switch1(config-vlan) name NATIVE_VLAN
Switch1(config)# interface gi0/0
Switch1(config-if)# switchport mode dynamic desirable
Switch1(config-if)# switchport trunk native vlan 99
02.Switch2(config)# vlan 99
Switch2(config-vlan) name NATIVE_VLAN
Switch2(config)# interface gi0/0
Switch2(config-if)# switchport mode dynamic desirable
Switch2(config-if)# switchport trunk native vlan 99
* You must create VLAN 99; else it the port configuration will
say VLAN 99 (inactive)
03.Switch1# show interfaces trunk
Switch2# show interfaces trunk
04.Switch1# show interface g0/0 switchport
Switch2# show interface g0/0 switchport
* VLAN 99 must be created else it will state
"Trunking Native Mode VLAN: 99 (Inactive)"
* both interfaces have to match or the trunk link will not
form properly. Once the trunk link is formed, all VLAN traffic
can pass over the trunk link
05.Switch1# show interfaces trunk
Switch2# show interface gi0/0 switchport
* with these commands, you are looking for the following:
- administrative mode:
- operational mode:
- status: trunking
- native vlan:
DYNAMIC/PASSIVE TRUNKING
Dynamic/Passive is where a DTP mode passively waits for other side to send DTP messages
PROCEDURE
Configure SW1 interface gi0/0 to passively trunk and wait for the other side to send DTP messages using vlan 99 as the native VLAN and using 802.1Q trunking protocol instead of ISL protocol
Configure SW2 interface gi0/0 to passively trunk and wait for the other side to send DTP messages using vlan 99 as the native VLAN and using 802.1Q trunking protocol instead of ISL protocol
Verify trunking between the two switches
Get a detailed view of the trunking configuration on a specific interface
Troubleshoot and determine why the interfaces are not trunking
Fix the issue IOT have the two switches form a "trunk" link
IMPLEMENTATION
01.Switch1(config)# vlan 99
Switch1(config-vlan) name NATIVE_VLAN
Switch1(config)# interface gi0/0
Switch1(config-if)# switchport trunk encapsulation dot1q
Switch1(config-if)# switchport mode dynamic auto
Switch1(config-if)# switchport trunk native vlan 99
02.Switch2(config)# vlan 99
Switch2(config-vlan) name NATIVE_VLAN
Switch2(config)# interface gi0/0
Switch2(config-if)# switchport trunk encapsulation dot1q
Switch2(config-if)# switchport mode dynamic auto
Switch2(config-if)# switchport trunk native vlan 99
03.Switch1# show interfaces trunk
Switch2# show interfaces trunk
* No trunk links will be established because both links are in a
passive state & are waiting for either side to initiate DTP
messages which will not happen when a trunk port is set to
dynamic auto
04.Switch1# show interface g0/0 switchport
Switch2# show interface g0/0 switchport
* VLAN 99 must be created else it will state
"Trunking Native Mode VLAN: 99 (Inactive)"
05.Switch1# show interfaces trunk
Switch2# show interface gi0/0 switchport
* with these commands, you are looking for the following:
- administrative mode:
- operational mode:
- status: trunking
- native vlan:
07.Switch1(config)# interface gi0/0
Switch1(config-if)# switchport mode dynamic desirable
Switch1(config-if)# do show interfaces trunk
Switch1(config-if)# do show interface gi0/0 switchport
* Having the two switches on dynamic auto will not form a trunk
- This is because both link will wait for the other side
to send DTP message which will never happen
- To fix the issue, configure one side to be either an
explicit trunk port or dynamic desirable state
