Solved: 891 Router - No ip address on vlan 2

liteultom · ‎10-15-2015

Hello all !

I am )very new to all this and I have to configure a cisco 891 router. So far I was doing ok but I have a problem connecting devices on vlan 2.

I don't want to assign vlan depending on the port, the devices are able to tag their own packets.

For now, when I connect a "classic" device, it goes on vlan 1 and get an ip address from my vlan 1 pool. Okay. Problems begin when I tell the device to tag its packet as belonging to vlan 2. As soon as I do that, I can't get any IP address assigned from my dhcp.

Here is my config file, anybody have an idea ? :)

Building configuration...

Current configuration : 2978 bytes
!
! Last configuration change at 14:20:32 UTC Thu Oct 15 2015 by tchavrier
version 15.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Cisco891
!
boot-start-marker
boot-end-marker
!
aqm-register-fnf
!
enable secret 5 XXXXXXXXXXXXXXXXXXXXXXXXX
enable password XXXXXXXXXXXXXXXXXXXXXXXXX
!
no aaa new-model
!
!
!
!
!
!

!
ip dhcp excluded-address 172.26.1.1 172.26.1.49
ip dhcp excluded-address 172.26.1.100 172.26.1.254
ip dhcp excluded-address 10.10.10.1 10.10.10.49
ip dhcp excluded-address 10.10.10.100 10.10.10.254
ip dhcp excluded-address 10.10.20.1 10.10.20.49
ip dhcp excluded-address 10.10.20.100 10.10.20.254
!
ip dhcp pool vlan1pool
 network 172.26.1.0 255.255.255.0
 default-router 172.26.1.254
 dns-server 208.67.220.220
!
ip dhcp pool vlan2pool
 network 10.10.10.0 255.255.255.0
 default-router 10.10.10.254
 dns-server 208.67.222.222
!
ip dhcp pool vlan3pool
 network 10.10.20.0 255.255.255.0
 default-router 10.10.20.254
 dns-server 208.67.222.222
!
!
!
ip cef
no ipv6 cef
!
!
!
!
!
multilink bundle-name authenticated
!
!
!
!
!
!
!
license udi pid C891F-K9 sn FCZ1939917U
!
!
username XXXXXXXXXXXXXXXXXXX privilege 15 secret 5 XXXXXXXXXXXXXXXXXXXXXXXXXXXX.
!
!
!
!
!
no ip ftp passive
!
!
!
!
!
!
!
!
!
!
interface BRI0
 no ip address
 encapsulation hdlc
 shutdown
 isdn termination multidrop
!
interface FastEthernet0
 ip address dhcp
 ip nat outside
 ip virtual-reassembly in
 duplex auto
 speed auto
!
interface GigabitEthernet0
 no ip address
!
interface GigabitEthernet1
 no ip address
!
interface GigabitEthernet2
 no ip address
!
interface GigabitEthernet3
 no ip address
!
interface GigabitEthernet4
 no ip address
!
interface GigabitEthernet5
 no ip address
!
interface GigabitEthernet6
 no ip address
!
interface GigabitEthernet7
 no ip address
!
interface GigabitEthernet8
 ip address dhcp
 ip nat outside
 ip virtual-reassembly in
 duplex auto
 speed auto
!
interface Vlan1
 ip address 172.26.1.254 255.255.255.0
!
interface Vlan2
 ip address 10.10.10.254 255.255.255.0
!
interface Vlan3
 ip address 10.10.20.254 255.255.255.0
!
interface Async3
 no ip address
 encapsulation slip
!
ip forward-protocol nd
ip http server
ip http authentication local
no ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
!
ip flow-top-talkers
 top 10
 sort-by bytes
 cache-timeout 60000
!
!
!
!
control-plane
!
!
!
mgcp behavior rsip-range tgcp-only
mgcp behavior comedia-role none
mgcp behavior comedia-check-media-src disable
mgcp behavior comedia-sdp-force disable
!
mgcp profile default
!
!
!
!
!
line con 0
 no modem enable
line aux 0
line 3
 modem InOut
 speed 115200
 flowcontrol hardware
line vty 0 4
 privilege level 15
 password haricotmarteaulitjaune
 login local
 transport input telnet
 transport output telnet
line vty 5 15
 password haricotmarteaulitjaune
 login local
 transport input telnet
 transport output telnet
!
scheduler allocate 20000 1000
!
end

Thanks !

Seb Rupik · ‎10-20-2015

Hi there,

If your connected devices are tagging their own packets (ie VLAN2) then the switchport will discard them.

Without any explicit configuration on the switchports, they will be configured with native VLAN1. This means any packet received on that switchport which does not have a VLAN tag will be tagged with VLAN ID 1. Any packets with tags will be ignored, but since you do not have trunking configured they will be dropped.

To make it work you would need to add the following:

!
int range gi0-8
 switchport trunk native vlan 1
 switchport trunk allowed vlan all
!

This would allow untagged packets to be forwarded (on VLAN1), but would also handle the packets which are being tagged by connected devices (providing the VLAN configuration exists on the router).

Hope that helps.

cheers,

Seb.

View solution in original post

Seb Rupik · ‎10-20-2015