From: Tarun Pahuja (pahujat@gmail.com)
Date: Wed Oct 24 2007 - 13:28:28 ART
Kuldip,
If you are changing the native vlan on the router subinterface for
vlan10, you must change the native vlan on the swicth trunk port as well. By
default the native vlan is 1. The native vlan must be the same on both ends
of the trunk.
Thanks,
Tarun
On 10/24/07, kuldip singh <dipa.singh@gmail.com> wrote:
>
> Hi,
>
> It seems like I can't get the native VLAN to work. As shown below
> I have two sub-interfaces configured on R4, vlan 10 and vlan 555. if the
> sub-interfaces are configured as trunk ports and the switchport is
> configured as trunk port I can ping the 10.10.10.201 and 131.10.160.5 (R5
> connected to switch 3). If I change the sub-interface on R4 (e0/1.10 ) to
> mark vlan 10 as native and change the config on switch 4 to mark the vlan
> 10
> as native. I can't ping 10.10.10.201 address, but I can still ping vlan
> 555
> ok.
> Can somebody spot the issue. (This is from one of the NMC documents).
>
>
> Thanks
>
>
> R4: (R4 connected to Switch 4)
>
>
> interface Ethernet0/1
> no ip address
> half-duplex
> !
> interface Ethernet0/1.10
> encapsulation dot1Q 10
> ip address 10.10.10.1 255.255.255.0
> no snmp trap link-status
> !
> interface Ethernet0/1.555
> encapsulation dot1Q 555
> ip address 131.10.160.1 255.255.255.0
> no snmp trap link-status
>
>
>
> SW4:
>
> interface FastEthernet0/4
> switchport trunk encapsulation dot1q
> switchport mode trunk
>
> interface Vlan10
> ip address 10.10.10.201 255.255.255.0
>
>
> SW3;
>
> interface FastEthernet0/5
> switchport access vlan 555
> switchport mode access
>
>
>
> Ping from R4;
>
> Rack9SW4#ping 10.10.10.201
>
> Sending 1, 100-byte ICMP Echos to 10.10.10.201, timeout is 2 seconds:
> !
> Success rate is 100 percent (1/1), round-trip min/avg/max = 4/4/4 ms
> Rack9SW4#
>
> Sending 1, 100-byte ICMP Echos to 131.10.160.5, timeout is 2 seconds:
> !
> Success rate is 100 percent (1/1), round-trip min/avg/max = 1/1/1 ms
> Rack9SW4#
>
>
>
>
> Now change the config on R4 and SW4 to make VLAN 10 native.
>
> R4:
>
> interface Ethernet0/1.10
> encapsulation dot1Q 10 native
> ip address 10.10.10.1 255.255.255.0
> no snmp trap link-status
> end
>
>
>
> SW4:
>
> interface FastEthernet0/4
> switchport trunk encapsulation dot1q
> switchport trunk native vlan 10
> switchport mode trunk
> end
>
>
> Ping from R4:
>
> Rack9R4#ping 10.10.10.201
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 10.10.10.201, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)
> Rack9R4#
>
> Rack9R4#ping 131.10.160.5
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 131.10.160.5, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/4 ms
> Rack9R4#
>
>
> debug on the route R4 indicates encapsulation failure when vlan 10 is made
> native.
>
> Oct 24 08:34:38.682: IP: s=10.10.10.1 (local), d=10.10.10.201
> (Ethernet0/1.10),
> len 100, sending
> Oct 24 08:34:38.686: IP: s=10.10.10.1 (local), d=10.10.10.201
> (Ethernet0/1.10),
> len 100, encapsulation failed.
> Oct 24 08:34:40.682: IP: tableid=0, s=10.10.10.1 (local), d=10.10.10.201
> (Ethern
> et0/1.10), routed via RIB
> Oct 24 08:34:40.682: IP: s=10.10.10.1 (local), d=10.10.10.201
> (Ethernet0/1.10),
> len 100, sending
>
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