add DTP VLAN and Subnetting

2026-05-13 17:26:51 +02:00
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+---
+id: 1778493954-IJHJ
+aliases:
+  - VLAN (Part 3)
+tags: []
+---
+
+# VLAN (Part 3)
+
+## Native VLAN on a router (ROAS)
+
+There 2 methods for configuring the native VLAN on a router:
+
+1.
+```Cisco
+R1(config)# int g0/0.10
+R1(config-subif)#encapsulaton dot1q *vlan-id* native
+```
+
+2.
+Configure the [[IP address]] for the native VLAN on the router's physical interface 
+(the command is not necessary)
+```Cisco
+R1(config)# int g0/0.10
+R1(config-subif)#ip address 192.168.1.62 255.255.255.192
+```
+
+## Layer 3 (Multilayer) switches
+
+- A multilayer switch is capable of both switching and routing.
+- It is 'Layer 3 aware'
+- You can assign IP addresses to its interfaces, like a router.
+- You can create virtual interfaces for each VLAN, and assign IP addresses to those interfaces.
+- You can configure routes on it, just like a router.
+- it can be used for inter-VLAN routing
+
+### Inter-VLAN routing via SVI
+
+- SVIs (Switch Virtual Interfaces) are the virtual interfaces you can assign IP addresses to 
+in a multilayer switch.
+- Configure each PC to use the SVI (Not the router) as their gateway address.
+- To send traffic to different subnets/VLANs, the PCs will send traffic to the switch,
+and the switch will route the traffic
+
+the command to enable Layer 3 routing on the switch is
+
+```Cisco
+SW2(config)#ip routing
+
+## this configure the interface as a 'routed port'
+## (Layer 3 port, not Layer 2 /switchport)
+SW2(config)#interface g0/1
+SW2(config-if)#no switchport
+
+## then you can configure an IP address on the interface like a regular router interface
+SW2(config-if)#ip address 192.168.1.193 255.255.255.252
+
+## then you can configure the default route
+SW2(config-if)#ip route 0.0.0.0 0.0.0.0 192.168.1.194
+```
+
+To configure SVI you can assign ip address to each vlan
+```Cisco
+SW2(config)#interface vlan10
+SW2(config-if)#ip address 192.168.1.62 255.255.255.192
+SW2(config-if)#no shutdown
+SW2(config)#interface vlan20
+SW2(config-if)#ip address 192.168.1.126 255.255.255.192
+SW2(config-if)#no shutdown
+SW2(config)#interface vlan30
+SW2(config-if)#ip address 192.168.1.190 255.255.255.192
+SW2(config-if)#no shutdown
+```
+
+1. The Vlan must exist on the switch
+2. The swithc must have at least one access port in the VLAN in an up/up state, AND/OR
+one trunk port that allows the VLAN that is in an up/up state
+3. The VLAN must not be shutdown (you can use the shutdown command to disable a VLAN)
+4. The SVI must not be shutdown (SVIs are disabled by default)
+
+## Review
+
+- Native VLAN on a router
+- Wireshark analysis
+- Layer 3 Switching/multilayer Switching
+
+**next lesson**
+- DTP (Dynamic Trunking Protocol)
+- VTP (VLAN trunking Protocol)
+