Router on the stick

diallodjeri · ‎08-13-2011

Hi folks,

I have configured vlan 2 and vlan 3 on my switch and trunk them to my router and I do have connectivity between those two vlans..When configured the router sub-interface f0/0.1,f0/0.2 and f0/0.3 I have used the fallowing ip address 10.37.37.1, 10.37.36.1and10.37.35.1 respectively for vlan 1,2 and 3. Host 1 on vlan1 ip address is 10.37.37.5 with default-gateway 10.37.37.1 and host 2 ip address 10.37.36.10 with default-gateway 10.37.36.1. I don't have connectivity between vlan 1 and any of the vlan I can't even ping the default-gateway that I have set for vlan 1 on router sub-interface from a host connect to vlan. In the router configuration under sub-int I did hard coded vlan 1 as native but it still don't work .What I'm missing here ?

Somasundaram Jayaraman · ‎08-13-2011

Hi

The configurations should be

Router example, for fa0/0.1

interface FastEthernet0/0.1
 encapsulation dot1q 1
 ip address 10.37.37.1 255.255.255.0

interface FastEthernet0/0.2
 encapsulation dot1q 2
 ip address 10.37.36.1 255.255.255.0

interface FastEthernet0/0.3
 encapsulation dot1q 3
 ip address 10.37.35.1 255.255.255.0


Let us consider the port connected to the router from switch is fa 0/1:

The configuration would be
 
switch(config)#int FastEthernet 0/1
switch(config-if)#switchport trunk encapsulation dot1q
switch(config-if)#switchport mode trunk

Hope this helps

Cheers
Somu



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Somasundaram Jayaraman · ‎08-13-2011

Also can you check this command on switch.

show interface switchport and see whether the vlans are mapped right??

Here interface no is the interface where the host is connected to the switch.

Cheers

somu

diallodjeri · ‎08-14-2011

This is exactely I have configured and that is why I do have connectivity between vlan 2 and 3.

You can see these output from the router and switch:

R1#sh vlan

Virtual LAN ID: 1 (IEEE 802.1Q Encapsulation)

vLAN Trunk Interface: Ethernet0/0.1

This is configured as native Vlan for the following interface(s) :

Ethernet0/0

Protocols Configured: Address: Received: Transmitted:

IP 10.37.37.1 0 0

Virtual LAN ID: 2 (IEEE 802.1Q Encapsulation)

vLAN Trunk Interface: Ethernet0/0.2

Protocols Configured: Address: Received: Transmitted:

IP 10.37.36.1 531 12

Virtual LAN ID: 3 (IEEE 802.1Q Encapsulation)

vLAN Trunk Interface: Ethernet0/0.3

Protocols Configured: Address: Received: Transmitted:

IP 10.37.35.1 0 0

R1#

--------------------------

R1#sh vlan

Virtual LAN ID: 1 (IEEE 802.1Q Encapsulation)

vLAN Trunk Interface: Ethernet0/0.1

This is configured as native Vlan for the following interface(s) :

Ethernet0/0

Protocols Configured: Address: Received: Transmitted:

IP 10.37.37.1 0 0

Virtual LAN ID: 2 (IEEE 802.1Q Encapsulation)

vLAN Trunk Interface: Ethernet0/0.2

Protocols Configured: Address: Received: Transmitted:

IP 10.37.36.1 531 12

Virtual LAN ID: 3 (IEEE 802.1Q Encapsulation)

vLAN Trunk Interface: Ethernet0/0.3

Protocols Configured: Address: Received: Transmitted:

IP 10.37.35.1 0 0

R1#

SW2#sh vlan

VLAN Name Status Ports

---- -------------------------------- --------- -------------------------------

1 default active Fa0/1, Fa0/4, Fa0/5, Fa0/6

Fa0/7, Fa0/8, Fa0/9, Fa0/10

Fa0/11, Fa0/12, Fa0/13, Fa0/14

Fa0/15, Fa0/16, Fa0/17, Fa0/18

Fa0/19, Fa0/20, Fa0/21, Fa0/22

Fa0/23

2 Sale active Fa0/2

3 Managment active Fa0/3

4 Marketing active

1002 fddi-default act/unsup

1003 token-ring-default act/unsup

1004 fddinet-default act/unsup

1005 trnet-default act/unsup

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------

1 enet 100001 1500 - - - - - 0 0

2 enet 100002 1500 - - - - - 0 0

3 enet 100003 1500 - - - - - 0 0

4 enet 100004 1500 - - - - - 0 0

1002 fddi 101002 1500 - - - - - 0 0

1003 tr 101003 1500 - - - - srb 0 0

VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2

---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------

1004 fdnet 101004 1500 - - - ieee - 0 0

1005 trnet 101005 1500 - - - ibm - 0 0

Remote SPAN VLANs

------------------------------------------------------------------------------

Primary Secondary Type Ports

------- --------- ----------------- ------------------------------------------

SW2#sh int trunk

Port Mode Encapsulation Status Native vlan

Fa0/24 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/24 1-4094

Port Vlans allowed and active in management domain

Fa0/24 1-4

Port Vlans in spanning tree forwarding state and not pruned

Fa0/24 1-4

SW2#

ajaju · ‎08-13-2011

Maybe you have not allowed vlan 1 on the trunk link between the two devices.

Look at the output of "show int trunk" on the switch and ensure that all 3 vlans are allowed to go over that link.

Also ensure that you have the same native vlan set on both devices.

For example, if you have vlan 1 as the native on the switch, ensure that you put in

encapsulation dot1q 1 native

under the fa0/0.1 interface of the router.

smogra · ‎08-14-2011

Hi,

Apart from what Somu and Aniruddha has given, you can refer to the below link as well for more understanding:

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a00800949fd.shtml#conf

This is a really good document and will really explain you stuffs very clearly.

Hope that helps.

Sweta

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diallodjeri · ‎08-14-2011

Thanks but I have red that document more than once.

Jon Marshall · ‎08-14-2011

Can you try

int fa0/1

ip address 10.37.37.1 255.255.255.0

int fa0/0.2

encapsulation dot1q 2

ip address 10.37.36.1 25.255.255.0

int fa0/0.3

encapsulation dot1q 3

ip address 10.37.35.1 255.255.255.0

Jon

diallodjeri · ‎08-14-2011

In the router on the stick configuration the main interface of the router should not get any ip address instead the sub-interface are configured.

Jon Marshall · ‎08-14-2011

Please give me some credit

You can do it either way ie. -

you can specify subinterfaces for all vlans

or

you can configure the native vlan on the main interface and then just use subinterfaces for the other vlans.

If your router supports the "native" keyword then you have done it the recommended way. However as it does not seem to be working i though it may be worth trying it the other way just to see if it works.

Jon

diallodjeri · ‎08-14-2011

You may be right but every documentation I have red they don't assign ip address to a main interface,the just put no shutdown.That is why I have said that

Jon Marshall · ‎08-14-2011

No problem, but if you ask for help then perhaps you ought to have a bit more trust in what people say.

I suspect this not the issue but it was worth trying. However as you seem to know more about this than me i'll drop out of this thread

Jon