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native vlan posted 10/24/2007
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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