2960 only passing 1 VLAN using trunk to router

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Nov 5th, 2008
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I have a remote office with a 2960 24 port switch connected to 2 2600 routers (redundancy). I'm using sub-interfaces on the routes configured for .1Q encapsulation to trunk 2 VLAN's from the switch to the routers.

1 of the routers only seems to see 1 of the VLANs. Here's the config of the router

interface FastEthernet0/0

no ip address

no ip redirects

speed 100



interface FastEthernet0/0.1

encapsulation dot1Q 1

ip helper-address

ip helper-address

no ip redirects


standby 1 ip

standby 1 priority 200

standby 1 preempt delay minimum 240

standby 1 track Serial0/0


interface FastEthernet0/0.2

encapsulation dot1Q 26

ip address

no ip redirects

standby 10 ip

standby 10 priority 150

fa0/0.1 VLAN 1 can't even ping it's HSRP neighbor nothing in it's arp cache either.

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mark.cronin Wed, 11/05/2008 - 06:56
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Whats the IP address on FA 0/0.1?

You only have the HSRP address configured

rshum Wed, 11/05/2008 - 06:59
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Yeah I had it shut down so it doesn't mess with the other router. I didn't realize I left out the interface address! thanks I'm going to give it a try right now.

rshum Wed, 11/05/2008 - 07:03
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I put in the address for fa0/0.1 and turned up the port but still wasn't able to ping across to the other router's interface nor anything on that VLAN.

rshum Wed, 11/05/2008 - 07:12
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The switch only supports .1Q encapsulation so here is the config on the ports connected to the routers

interface FastEthernet0/15

description trunk to rtr1

switchport mode trunk

switchport nonegotiate

speed 100

duplex full

interface FastEthernet0/24

description trunk to rtr2

switchport mode trunk

switchport nonegotiate

speed 100

duplex full

port 0/15 is connected to the working router and 0/24 is the one not working.

mark.cronin Wed, 11/05/2008 - 07:10
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I would also change from vlan 1 to another


Check that you have configured the vlans on the switch


vlan database

vlan 1

vlan 26

vlan x



rshum Wed, 11/05/2008 - 08:48
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Yeah I was planning to but I inherited this network and it's on my to do list. It shouldn't be a show stopper though because it is working on the other router.

nathan.haley Wed, 11/05/2008 - 07:13
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for the interface FastEthernet0/0.1

change encapsulation dot1q 1


encapsulation dot1g 1 native

That should fix you all up :)

This will allow the trunk to form :)

on a side bar the switch has to be configured as a trunk on the other end you have to have the vlans in the database and if you change the native vlan on the switch side you wil have to create another subinterface on the router with that vlan specified as native :)

rshum Wed, 11/05/2008 - 08:40
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I tried that but it doesn't take. I was concerned from the beginning that I'm running Version 12.1(20) and it might be sort of buggy or different. My working router is running Version 12.3(6f) and I do have the native in there. I haven't seen anything in the 12.1 notes that indicates this would be a problem though.

lamav Wed, 11/05/2008 - 08:46
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This is getting confusing.

Why dont you post the switch config as well as the router configs. And make sure you post the configs that SHOULD be there (ie get rid of "shutdowns"



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