So this is what our topology looks like at the moment.
On router 1, let’s have a look at Spanning Tree.
So sh spanning-tree vlan 1
we can see that were running the IEEE Compatible Spanning Tree protocol or CST
the priority is 8192
this switch is the root of the Spanning Tree port 81
for F2/0 is forwarding on VLAN 1 and so is F2/2
In other words, Spanning Tree is forwarding on these 2 ports.
What about router 2? sh spanning-tree FastEthernet 2/0 is forwarding
and so is FastEthernet 2/2.
Scrolling up, we can see the local switches priority
and the priority of the root which is router 1.
Now before I going any further you may encounter a problem with this default configurations.
The RAM may be too little and you may need to configure some disk space.
As an example, on router 1 if I'll try configure VLAN 2 or VLAN 3
notice we're running out of space, if I configure VLAN 4, we're running out of space.
So what I suggest you do before going any further
shut everything down make sure that you configure enough RAM on your routers
and configure some disk space for the VLAN database.
So I'll configure that on both routers, give it enough memory
and configure some disk space for the VLAN database.
Before I start the map I'll also cable another link between the 2 routers
so that we can see Spanning Tree blocking ports.
So I'll start them up
here’s router 1 now you'll notice I lost the configuration
so make sure that you change your settings before you start.
So set some disk space and set enough memory
But I'm gonna set this guy as the root and router 2 I’m gonna set as the second root.
So basically what I did previously so sh spanning-tree
what you can see is that FastEthernet 2/0 is forwarding on VLAN 1
2/1 is forwarding on VLAN 1, 2/2 is forwarding on VLAN 1
and that makes sense because router 1 is the root of our topology.
What about router 2? so sh spanning-tree vlan 1
notice FastEthernet 2/0 is forwarding but FastEthernet 2/1 is blocking
FastEthernet 2/2 is forwarding
Spanning Tree has blocked this link which is correct
and expected because we have a loop in this topology.
So let's configure an IP address on VLAN 1
ip address 10.1.1.254 no shut
router 2 int vlan 1 ip address 10.1.1.253
one of the things I’m gonna do before I go any further
is configure these 2 links as trunk ports
so on router 1 interface f2/0 switchport mode trunk
interface 2/1 switch port mode trunk.
I’ll do the same on this switch
switchport mode trunk interface 2/1 switchport mode trunk.
So I’ve manually turned off DTP or Dynamic Trunk Protocol.
So now let’s have a look
sh spanning-tree vlan 1
FastEthernet 2/0 is forwarding 2/1 is forwarding and 2/2 is forwarding.
You can also use commands such as show int f2/0 switchport
and what you can see here is that it’s been made a trunk
the encapsulation is 802.1Q, the native VLAN is VLAN 1
and all VLAN are permitted on switch 2 or router 2 we can do the same thing.
sh int 2/0 switchport
It’s been configured as a trunk, it’s operating as a trunk.
Encapsulation used is 802.1Q, native VLAN is VLAN 1
and all VLANs are permitted on the router.
So we’ve configured these 2 links to use 802.1Q
I’ve configured them to use static trunking rather than DTP
let me show you an example of VTP before I configure the PC.
So on router 1 show vtp status it’s configured as a server.
sh vlan
now this will show VLAN switch
sh vlan switch
shows me the default VLAN for Ethernet and token ring and FDDI VLANs.
On router 2 show vlan-switch shows me the default VLANs
show vtp status shows me that this is also configured as a server
so these are the defaults.
So let’s create VLAN 2 and what I’ll do is set the VTP domain to CCNA
and you can see something else happened on the second router
it's complaining about the VLAN database
so if you get an issue like this.
So show flash
notice we’ve got an unpartitioned flash and we told to format it.