Steps to Configure and Verify Interswitch Connectivity
VLAN stands for Virtual Local Area Network. It is a 12-bit identity used to create multiple broadcast domains in a switch. VLAN ranges from 0 to 4095 (VLAN 0 and VLAN 4095 are reserved and not used).
Modes of Switch port:
Administrative mode:
- This Switch Port mode is configured by the admin.
- Types of Administrative mode:
- Static Access – (no negotiation of the trunk)
- Static Trunk – (forces formation of the trunk)
- Dynamic Desirable – (initiates negotiation of the trunk)
- Dynamic Auto – (wait for the negotiation of the trunk)
Operational Mode:
- This is the resulting mode of the Switch Port after the negotiation (the result of the configuration done by the admin).
- Types of Operational mode:
Access Mode – If the port is in access mode then the port can carry only one VLAN data. It is only configured on the ports connected to the end users.
switch(config)#int <interface_id> switch(config-if)#Switch Port mode access
Trunk Mode -If the port is in Trunk mode then the port can carry multiple VLAN data using the Layer 2 encapsulation protocol (either Dot1Q or ISL).
switch(config)#int <interface_id> switch(config-if)#Switch Port mode trunk
Configuring and Verifying Inter-switch Connectivity:
Configure IP Address On the Virtual PCs:
PC1:
PC2:
PC3:
PC4:
Configure VLANs On both Switches:
Switch(config)#VLAN 10 Switch(config-VLAN)#exit Switch(config)#VLAN 20 Switch(config-VLAN)#exit
Switch1:
Switch2:
Add the Switch Ports Connected to End-Users:
Switch(config)#int <interface_id> Switch(config-if)#Switch Port mode access Switch(config-if)#Switch Port access VLAN <VLAN_number> Switch(config-if)#exit
Switch1:
Switch2:
Let’s check the connectivity between PCs Right now.
As you can see, none of the PCs can communicate to each other.
- PC1 and PC2 are not able to communicate because of different VLANs.
- PC1 and PC3 are not able to communicate because there is no Inter-switch connectivity.
- PC1 and PC4 are not able to communicate because of different VLANs and no Inter-switch connectivity.
Configure Trunk Ports on Switch:
Switch(config)#int <interface_id> Switch(config-if)#Switch Port trunk encapsulation <dot1q/isl> Switch(config-if)#Switch Port mode trunk Switch(config-if)#exit
Switch1:
Switch2:
Verifying Connectivity:
PC1 to PC3:
PC2 to PC4:
As you can see, Inter-switch connectivity has been established and the connection is successful in devices within the same VLANs.
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