Vlan sub-interface puzzler

Unanswered Question
Mar 6th, 2009
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Having an issue getting a vlan to work. I have a Cisco 2801 router configured with sub interfaces and have some questions. I have a 10.1.1.0 network which is Vlan 1 and a 10.1.2.0 network (both /24)Vlan 2 The switch is configured as a trunk on the uplink and on one port with Vlan 1 as native and Vlan 2 are on both ports. Vlan 1 works fine from the trunked port but Vlan 2 doesn't. Meening I can use a 10.1.1.0 address and ping but when I use a 10.1.2.0 address I cant ping the gateway on that network. Here is my router config:

interface FastEthernet0/1

description INSIDE INTERFACE - VLAN 1

ip address 10.1.1.1 255.255.255.0

ip access-group 110 in

ip nbar protocol-discovery

ip flow ingress

ip flow egress

ip nat inside

ip virtual-reassembly

ip policy route-map NO-NAT-STATIC-IP-FOR-VPN-CLIENTS

load-interval 30

speed 100

full-duplex

no cdp enable

!

interface FastEthernet0/1.2

description INSIDE INTERFACE Voice - VLAN 2

encapsulation dot1Q 2

ip address 10.1.2.1 255.255.255.0

ip helper-address 10.1.1.14

no cdp enable


Here is a sho ip int brie

Vlan1 unassigned YES NVRAM up down


Vlan2 unassigned YES unset up down


Vlan3 192.168.1.1 YES NVRAM up up



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Overall Rating: 4 (1 ratings)
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adamclarkuk_2 Fri, 03/06/2009 - 05:41
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Hi


As a side not, the use of VLAN 1 is not recommended for data, see post below


hxxp://forums.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Network%20Infrastructure&topic=LAN%2C%20Switching%20and%20Routing&topicID=.ee71a04&fromOutline=&CommCmd=MB%3Fcmd%3Ddisplay_location%26location%3D.2cd256f3


Try adding vlan 1 to a sub interface as well, just add native to the end of the encapsulation command.


interface FastEthernet0/1

speed 100

full-duplex

no cdp enable


FastEthernet0/1.1

description INSIDE INTERFACE - VLAN 1

encapsulation dot1Q 1 native

ip address 10.1.1.1 255.255.255.0

ip access-group 110 in

ip nbar protocol-discovery

ip flow ingress

ip flow egress

ip nat inside

ip virtual-reassembly

ip policy route-map NO-NAT-STATIC-IP-FOR-VPN-CLIENTS

load-interval 30


interface FastEthernet0/1.2

description INSIDE INTERFACE Voice - VLAN 2

encapsulation dot1Q 2

ip address 10.1.2.1 255.255.255.0

ip helper-address 10.1.1.14

no cdp enable




viyuan700 Fri, 03/06/2009 - 06:38
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In my opinion ur setup is not working because you have given IP to etherent port 0/1 and then you are assigning on more to its subinterface.


When you use subinterface you dont give ip to that port. You just define subinterface.



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