nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

encapsulation/trunking

liven

Is there anything I need to do to turn this on , on my routers?

I hava 2610 with IOS 12.3(a)

I can create the sub interfaces but I can't get the command

encapsulation to work

any thoughts?

Find more posts tagged with

SAVE $250 on Your CISCO Boot Camp — Use Code "EXAM26"

Exclusively for TechExams members for Infosec Boot Camps starting before April 30, 2026

View CISCO Boot Camps

Comments

Plazma

encapsulation dot1q <vlan #> is the proper command in the subinterface

Plazma

or encapsulation isl <vlan #> if you use isl

not all switches support ISL though

liven

I just need a good tutorial for this anyone know of one?

liven

I think I am geting close...

But everytime I enable one of the vlans, the management vlan goes down...

It is like I can only have one vlan up at a time...

SUggestions?

Plazma

best bet is to paste your config with the code command in bbcode

liven

bbcode?

Plazma

oh sorry .. format it with the code buttons up above.. itll say code and /code but in between the []

liven

hmm whats the best way to get the entire config off the switch?

liven

also should the management vlan not participate in the intervlan communication?

Plazma

the mgt vlan should be the 'native vlan' if im not mistaken and shouldnt be included at all in any encapsulation.. as it is the native vlan and travels like anything else (If im wrong someone correct me)

liven

Man this is driving me nuts...

Every time I create a new vlan

assign it to a port, and then bring it up, it shuts down all the other vlans...

how do you have more than one active vlan?

Plazma

you just create them and they are 'active' you only assign an ip to vlan 1 , or w/e your management vlan is

you dont include vlan 1 in any kind of encapsulation/trunking (vlan 1 or your mgt vlan)

show vlan and paste it here

liven

Yes that is what I have

router

interface fa 0/0
ip address 192.168.1.201 255.255.255.0

interface fa 0/0.5
encapsulation dot1Q 5
ip address 192.168.2.2 255.255.255.0

switch

interface FastEthernet0/22
switchport mode trunk
no ip address
duplex full
speed 100

interface FastEthernet0/23
switchport access vlan 5
switchport mode access
no ip address

interface FastEthernet0/24
switchport access vlan 7
no ip address
duplex half
speed 10
!
interface Vlan1
ip address 192.168.1.71 255.255.255.0
no ip route-cache
shutdown
!
interface Vlan5
ip address 192.168.2.1 255.255.255.0
no ip route-cache
shutdown
!
interface Vlan7
ip address 192.168.3.1 255.255.255.0
no ip route-cache
!

!

Netstudent

nevermind you guys are too fast for me..

Plazma

thats the problem

fa0/0 shouldnt have an ip address

interface fa0/0
no ip address
no shutdown

the subinterfaces will have ip's, but not the acutal interface

liven

Ok so the vlans I want to route, should not have IP addresses?

Plazma

you also need another subint for vlan 7

liven

That is what I was thinking,

but dtlokee

posted this config

interface fastethernet 0/0
ip address 192.168.1.1 255.255.255.0
!
interface fastethernet 0/0.2
encapsulation dot1q 2
ip address 192.168.2.1.255.255.255.0
!
interface fastethernet 0/0.3
encapsulation dot1q 3
ip address 192.168.3.1 255.255.255.0

which made me think it was possible

liven

Plazma wrote:

you also need another subint for vlan 7

yes I know

just didn't get that far.

I wanted to get one working before I messed with the others.

Plazma

the physical interface should not have an IP, the subinterfaces need one

liven

I really need to try to get it to work like dtlokee displayed

Because the only router I have that supports sub interfaces with encapsulation is a dynamips router bridged to a real ethernet nic...

THen to a catalyst switch....

it is one big mess, but I really want it to work

Plazma

Remove the IP from the ethernet interface fa0/0 on the router, put ip address on the sub interfaces, set encapsulation

no shutdown on the other vlans that have shutdown on them

your done

liven

Yes but if I do that then I lose connectivity to the virtual router

Its a virtual router running on a linux box.

So I have to have an IP address on the physical interface. It shares that interface with the host pc.

Then that interface is connected to a switch....

I know it sounds ate up .... But its the best I can do...

Plazma

ohhhh crap

i forgot this was dynamips...

hmm.. yea check with dtlokee on it..

sorry to interrupt you..

liven

Its all good man I appriciate the help.

I just am losing my mind

THis is not 100% dynamips it is 1/2 dynamips 1/2 real gear....

What a nightmear....

THe fun never ends!!!!

liven

The part I can't understand is when I do a

no shut

on the other vlans that are not IP'd it shuts down all other vlans

say vlan 1 is up and up

and 5 and 7 are down

I do a no shut on 5

and 1 and 7 go down...

1 is the only vlan with an IP;...

Ideas anyone??

liven

Weird..

Seems to be kind of working...

I can ping things from the router but not the switch...

router A is doing rip routing for 192.168.0.0

then there are 2 sub interfaces on these networks
192.168.2.0/24
192.168.3.0/24

From router A I can ping hosts on those networks, but from the swich with the trunk I can not....

Weird..

Netstudent

You can only have one VLAN interface up at a time. Secondly, you can put a subnet on the physical interface of the router and use that subnet for the native vlan because the native vlan is not encapsulated with dot1q trunking. So on your router you could leave the IP on the physical interface and then on your switch you could use that subnet as the management vlan or use it for the native vlan.

Also make sure the right VLAN interface IP is enabled. Looks like the you have the wrong vlan interface enabled.

Also if you are trying to ping remote subnets from that switch, I think you will need the ip default-gateway command in global configuration mode.

liven

Ok...

I mean I think I got it partially working...

I only have one ip on the switch.

liven

I have vlan 1 enabled now

5 and 7 are down

from the router I can ping everything on vlan 1, 5 and 7

and I can telnet into any of those devices that are setup to allow it (one is a freebsd box and freebsd doesn't allow telnet by default).

But form all the devices on the vlans 5, and 7 I can not ping the other subnets or the host router.

But I can ping the sub interface IP for the sub itnterface the device is on.

For instance

freebsd host on vlan 5 subnet .2.0/24 can ping sub int on router 2.1, but can not ping the .1 or .3 subnets....

I have rip running on the router and I am specifying 192.168.0.0, shoud I change that to 192.168.1.0, 192.168.2.0 and 192.168.3.0???

Thanks