Re: Weird configuration with route statements

KyleWhitaker · ‎09-11-2019

Hello All,

my name is Kyle and I have secured a new job and am starting to manage my new network.

I am a bit confused as to how my routing statements should be setup on my switches.

I have tried to loosely setup our network in packet tracer to see where I am messing up my route statements at.

I have uploaded a loose copy of our network diagram here :

I have applied the ip addresses listed above each device to VLAN 1 on all the 3560's.

I have entered route statements on each 3560 pointing to the ip address on the vlan of the switch i want the traffic to go to.

so as an example on Switch 1 I entered 10.10.158.0 255.255.255.0 10.10.157.251

then on switch 2 I entered 10.10.158.0 255.255.255.0 10.10.158.248

all ports are in the default VLAN of VLAN 1. The links in between are trunk links.

Is this not correct? I am not able to get connectivity between my two PC's in my packet tracer example

Seb Rupik · ‎09-11-2019

Hi there,
There is something not right with your configuration.
You only mention VLAN1 in your topology, yet your static route statements show the subnet 10.10.158.0/24 which implies that you must also have 10.10.157.0/24 which will need to be in a VLAN of its own.

It is hard to determine from your diagram, but either switch2 or switch3 must have a Layer3 interface in both VLANs. It is this switch which you should configure as the VLAN/ subnet gateway.

For example, say it is switch2. The config should look like:

!
vlan1,2
!
int vlan 1 
ip address 10.10.157.251 255.255.255.0
!
int vlan 2
ip address 10.10.158.251 255.255.255.0
!
int fa0/1
switchport mode trunk
switchport trunk allowed vlan 1
no shut
!
int fa0/24
switchport mode trunk 
switchport trunk allowed vlan 2
no shut
!
ip routing
!

Now on switch 1:

!
int fa0/1
switchport mode trunk
switchport trunk allowed vlan 1
no shut
!
int fa0/24
switchport mode access
switchport access vlan 1
not shut
!
ip route 10.10.158.251 255.255.255.0 10.10.157.251
!

Switch3:

!
vlan 2
!
int range fa0/1, fa0/24
switchport mode trunk
switchport trunk allowed vlan 2
no shut
!
ip route 10.10.157.251 255.255.255.0 10.10.158.251
!

Switch4:

!
int fa0/1
switchport mode trunk
switchport trunk allowed vlan 2
no shut
!
int fa0/24
switchport mode access
switchport access vlan 2
not shut
!
ip route 10.10.157.251 255.255.255.0 10.10.158.251
!

Now for the PCs, they need the following gateways configured:

PC0 : 10.10.157.251
PC1 : 10.10.158.251

What we have achieved is a Layer2 network (VLAN1) from Switch2 towards PC0 and also extended the Layer2 network (VLAN2) from switch2 to PC1 via switches 3 and 4. Switch2 acts as the Layer3 gateway for both subnets and it is there that we do the inter-VLAN routing.

cheers,

Seb.