From: Carlos Mendioroz (tron@huapi.ba.ar)
Date: Tue Mar 14 2006 - 08:37:45 GMT-3
There used to be a problem in some routers with ARP "management" of
the native VLAN. I Know this happens in 2610s. May be related.
Debug arp in the router (A) and see if the request/response are "routed"
to different interfaces (main/.20)...
You may try to move the native vlan config to the main interface
and see if that helps.
Bottom line, it should work. Native vlan is untagged by default.
-Carlos
ccieben@cox.net @ 13/3/2006 20:25 -0600 dixit:
> Hello,
>
> I have the following attached to a 3550:
> Port 0/1 - trunked back to a Router A. I am allowing Vlan 10 & 20 & stating that 20 is native.
> Port 0/5 - a Vlan 20 access port attached to Router B.
>
> Router A & Router B are both on the same subnet.
>
> With the 3550 in its normal state - Router A & Router B cannot ping each other. Once I add the command:
> 3550(config)#vlan dot1q tag native
> Router A & Router B are able to ping each other... I thought that command would only be useful in an SP environment where 1Q/L2 tunneling was being performed.
>
> I thought these untagged packets were automatically part of vlan 20? What is the logic of why these devices can't "speak".... can someone help me understand the logic?
>
> TIA - Ben
>
> ***Router A
> interface Ethernet0/0.20
> encapsulation dot1Q 20 native
> ip address 172.16.17.1 255.255.255.0
> end
>
> ***Router B
> interface FastEthernet0/0
> ip address 172.16.17.6 255.255.255.0
> end
>
> ***3550
> interface FastEthernet0/1
> description to ROUTER-A
> switchport trunk encapsulation dot1q
> switchport trunk native vlan 20
> switchport trunk allowed vlan 10,20
> switchport mode trunk
> end
>
> interface FastEthernet0/5
> description to ROUTER-B
> switchport access vlan 20
> switchport mode access
> end
>
> 3550#show int trun
>
> Port Mode Encapsulation Status Native vlan
> Fa0/1 on 802.1q trunking 20
> <snip>
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sat Apr 01 2006 - 10:07:38 GMT-3