Re: ip vlan overlapping

Darrinmc · ‎02-27-2019

Hi all, I am attempting to connect 3 routers to a main router as part of a larger setup.

the relevant IP addressing table is :

Router1 (on F0/0/1) 192.168.3.2/26

Router2 (on F0/0/2 192.168.3.66/26

Router3 (on F0/0/3) 192.168.3.130/26

Main Router F0/0/1 - 192.168.3.1/26 F0/0/2 -192.168.3.65/26 F0/0/3 192.168.3.129/26

As they are on Layer 2 ports I have tried to assign Vlans ( R1- vlan10, R2-vlan20 & R3 vlan30) for the IP addressing but because they are all on the same subnet, I get a vlan overlapping error. Is there another way to assign Vlan IP's that wont get this error?

Any assistance appreciated.

Thanks

Darrinmc

Mark Malone · ‎02-27-2019

As an option you could isolate them using VRFs so there not in same routing space , may work for you as they will be in separate tables

Jon Marshall · ‎02-27-2019

I am not following, they are not all on the same subnet ie. the only devices on the same subnet are the two on 192.168.3.0/26.

Jon

Darrinmc · ‎02-28-2019

I must be misunderstanding subnets ? I would think these are all on the same subnet ?

192.168.3.2/26

192.168.3.66/26

192.168.3.130/26

192.168.3.1/26

192.168.3.65/26

192.168.3.129/26

You said only 2 are on subnet 192.168.3.0/26 ? Which would they be?

Jon Marshall · ‎02-28-2019

Sorry my mistake, you have 3 different subnets -

192.168.3.0 255.255.255.192 -> which includes 192.168.3.1 and 192.168.3.2
192.168.3.64 255.255.255.192 -> which includes 192.168.3.65 and 192.168.3.66
192.168.3.128 255.255.255.192 -> which includes 192.168.3.129 and 192.168.3.130

Jon

balaji.bandi · ‎02-27-2019

Make sure no other VLAN interface already configured in the main router before you configure this.

post main router configuration to look.

BB

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Darrinmc · ‎02-28-2019

ERROR MESSAGE
HQ(config)#int vlan 20
HQ(config-if)#
%LINK-5-CHANGED: Interface Vlan20, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan20, changed state to up

HQ(config-if)#ip address 192.168.3.65 255.255.255.192
% 192.168.3.64 overlaps with Vlan10
HQ(config-if)#

hostname HQ
!
ip cef
no ipv6 cef
!
license udi pid CISCO1941/K9 sn FTX15243FH3
!
spanning-tree mode pvst
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface FastEthernet0/0/0
switchport mode access
!
interface FastEthernet0/0/1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/0/2
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/0/3
switchport access vlan 30
switchport mode access
!
interface Serial0/1/0
ip address 10.20.20.1 255.255.255.252
clock rate 2000000
!
interface Serial0/1/1
ip address 10.10.10.2 255.255.255.252
clock rate 2000000
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
mac-address 0030.f25c.4d01
ip address 192.168.3.1 255.255.255.128
!
interface Vlan20
mac-address 0030.f25c.4d02
no ip address

hostname R1
!
no ip cef
no ipv6 cef
!
spanning-tree mode pvst
!
interface Loopback1
ip address 172.16.0.1 255.255.255.0
!
interface Loopback2
ip address 172.16.1.1 255.255.255.0
!
interface Loopback3
ip address 172.16.2.1 255.255.255.0
!
interface Loopback4
ip address 172.16.3.1 255.255.255.0
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface FastEthernet0/0/0
switchport mode access
!
interface FastEthernet0/0/1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/0/2
switchport mode access
!
interface FastEthernet0/0/3
switchport mode access
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
mac-address 0002.4a21.0d01
ip address 192.168.3.2 255.255.255.192
!
router ospf 10
router-id 1.1.1.1
log-adjacency-changes
network 192.168.3.0 0.0.0.63 area 10
network 172.16.0.0 0.0.0.255 area 10
network 172.16.1.0 0.0.0.255 area 10
network 172.16.2.0 0.0.0.255 area 10
network 172.16.3.0 0.0.0.255 area 10
!
ip classless

Darrinmc · ‎02-28-2019

Thanks for taking the time to review.

ERROR MESSAGE
HQ(config)#int vlan 20
HQ(config-if)#
%LINK-5-CHANGED: Interface Vlan20, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan20, changed state to up

HQ(config-if)#ip address 192.168.3.65 255.255.255.192
% 192.168.3.64 overlaps with Vlan10
HQ(config-if)#

hostname HQ
!
ip cef
no ipv6 cef
!
license udi pid CISCO1941/K9 sn FTX15243FH3
!
spanning-tree mode pvst
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface FastEthernet0/0/0
switchport mode access
!
interface FastEthernet0/0/1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/0/2
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/0/3
switchport access vlan 30
switchport mode access
!
interface Serial0/1/0
ip address 10.20.20.1 255.255.255.252
clock rate 2000000
!
interface Serial0/1/1
ip address 10.10.10.2 255.255.255.252
clock rate 2000000
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
mac-address 0030.f25c.4d01
ip address 192.168.3.1 255.255.255.128
!
interface Vlan20
mac-address 0030.f25c.4d02
no ip address

hostname R1
!
no ip cef
no ipv6 cef
!
spanning-tree mode pvst
!
interface Loopback1
ip address 172.16.0.1 255.255.255.0
!
interface Loopback2
ip address 172.16.1.1 255.255.255.0
!
interface Loopback3
ip address 172.16.2.1 255.255.255.0
!
interface Loopback4
ip address 172.16.3.1 255.255.255.0
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface FastEthernet0/0/0
switchport mode access
!
interface FastEthernet0/0/1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/0/2
switchport mode access
!
interface FastEthernet0/0/3
switchport mode access
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
mac-address 0002.4a21.0d01
ip address 192.168.3.2 255.255.255.192
!
router ospf 10
router-id 1.1.1.1
log-adjacency-changes
network 192.168.3.0 0.0.0.63 area 10
network 172.16.0.0 0.0.0.255 area 10
network 172.16.1.0 0.0.0.255 area 10
network 172.16.2.0 0.0.0.255 area 10
network 172.16.3.0 0.0.0.255 area 10
!
ip classless

rasmus.elmholt · ‎02-27-2019

Hi there

Could you please make sure you type the correct netmask when you configure the ip address on the main router(255.255.255.192).
And maybe share with us the error you get when you try to configure the interfaces

Darrinmc · ‎02-28-2019

Thanks for taking the time to review.

This is the error message when I try to assign IP to VLAN 20, and then config for HQ and R1. both connected via F0/0/1. The same happens when I do the same for R2 and R3,

ERROR MESSAGE
HQ(config)#int vlan 20
HQ(config-if)#
%LINK-5-CHANGED: Interface Vlan20, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan20, changed state to up

HQ(config-if)#ip address 192.168.3.65 255.255.255.192
% 192.168.3.64 overlaps with Vlan10
HQ(config-if)#

hostname HQ
ip cef
no ipv6 cef
license udi pid CISCO1941/K9 sn FTX15243FH3
spanning-tree mode pvst
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown

!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface FastEthernet0/0/0
switchport mode access
!
interface FastEthernet0/0/1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/0/2
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/0/3
switchport access vlan 30
switchport mode access
!
interface Serial0/1/0
ip address 10.20.20.1 255.255.255.252
clock rate 2000000
!
interface Serial0/1/1
ip address 10.10.10.2 255.255.255.252
clock rate 2000000
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
mac-address 0030.f25c.4d01
ip address 192.168.3.1 255.255.255.128
!
interface Vlan20
mac-address 0030.f25c.4d02
no ip address

hostname R1
!
no ip cef
no ipv6 cef
!
spanning-tree mode pvst
!
interface Loopback1
ip address 172.16.0.1 255.255.255.0
!
interface Loopback2
ip address 172.16.1.1 255.255.255.0
!
interface Loopback3
ip address 172.16.2.1 255.255.255.0
!
interface Loopback4
ip address 172.16.3.1 255.255.255.0
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
shutdown
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface FastEthernet0/0/0
switchport mode access
!
interface FastEthernet0/0/1
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/0/2
switchport mode access
!
interface FastEthernet0/0/3
switchport mode access
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
mac-address 0002.4a21.0d01
ip address 192.168.3.2 255.255.255.192
!
router ospf 10
router-id 1.1.1.1
log-adjacency-changes
network 192.168.3.0 0.0.0.63 area 10
network 172.16.0.0 0.0.0.255 area 10
network 172.16.1.0 0.0.0.255 area 10
network 172.16.2.0 0.0.0.255 area 10
network 172.16.3.0 0.0.0.255 area 10
!
ip classless

Mark Malone · ‎02-28-2019

Take a look at this doc , what i was talking about ysterday

https://packetu.com/2012/07/12/vrfing-101-understing-vrf-basics/

balaji.bandi · ‎02-28-2019

Looking high level :

HQ(config)#int vlan 20
HQ(config-if)#
%LINK-5-CHANGED: Interface Vlan20, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan20, changed state to up

HQ(config-if)#ip address 192.168.3.65 255.255.255.192
% 192.168.3.64 overlaps with Vlan10
HQ(config-if)#

You VLAN 10 have wrong mask, dont you think so ?

interface Vlan10
mac-address 0030.f25c.4d01
ip address 192.168.3.1 255.255.255.128 (192 /26, as per your original email)

BB

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rasmus.elmholt · ‎03-01-2019

Hi

interface vlan 10 on the host HQ has the wrong subnetmask.
You have configured the subnet mask of 255.255.255.128= /25
This means the subnet is from 192.168.3.0-127 and therefor it overlaps with the ip you try to configure on VLAN20.

Change the ip addres on vlan 10 to 192.168.3.1 255.255.255.192 should do the trick.