CCNA Notes

200-301 Exam Prep

Progress0/67

0% complete

Practice TestsNew
1Networking Devices2Interfaces And Cables3OSI Model and TCP/IP Suite4Intro to the CLI5Ethernet LAN Switching - Part 16Ethernet LAN Switching - Part 27IPv4 Addressing - Part 18IPv4 Addressing - Part 29Switch Interfaces10The IPv4 Header11Routing Fundamentals - Part 111Static Routing - Part 212Life of a Packet13Subnetting - Part 114Subnetting - Part 215Subnetting (VLSM) - Part 316VLANs - Part 117VLANs - Part 218VLANs - Part 319DTP / VTP20Spanning Tree Protocol - Part 121Spanning Tree Protocol - Part 222Rapid Spanning Tree Protocol23Etherchannel24Dynamic Routing25RIP / EIGRP26OSPF - Part 127OSPF - Part 228OSPF - Part 329First Hop Redundancy Protocol30TCP and UDP31IPv6 - Part 132IPv6 - Part 233IPv6 - Part 334Standard Access Control List35Extended Access Control List36CDP and LLDP37NTP - Network Time Protocol38DNS - Domain Name System39DHCP - Dynamic Host Configuration Protocol40SNMP - Simple Network Management Protocol41SYSLOG42SSH - Secure Shell43FTP and TFTP44NAT (Static) - Part 145NAT (Dynamic) - Part 246QoS (Voice VLAN) - Part 147QoS (Quality of Service) - Part 248Security Fundamentals49Port Security50DHCP Snooping51Dynamic ARP Inspection52LAN Architectures53WAN Architectures54Virtualization and Cloud - Part 154Virtualization (Containers) - Part 254Virtualization (VRF) - Part 355Wireless Fundamentals56Wireless Architectures57Wireless Security58Wireless Configuration59Introduction to Network Automation60JSON, XML, and YAML61REST APIs62Software Defined Networking63Ansible, Puppet, and Chef67CCNA Complete Cheatsheet
/VLANs - Part 3
Topic 183 min read

VLANs - Part 3

/
Tip: Select text to highlight or pin your reading position

18. VLANS : PART 3

NATIVE VLAN ON A ROUTER (ROAS)

imageClick to enlarge

Native VLAN untagged frames are faster and more efficient (smaller) than tagged ones.

Let’s reset all SWITCHES (SW1 and SW2) to native vlan 10

imageClick to enlarge

There are TWO methods of configuring the native VLAN on a router:

  • Use the command “encapsulation dot1q <vlan-id>” on a Sub-Interface

imageClick to enlarge

OR

  • Configure the IP address for the native VLAN on the router’s physical interface (the “encapsulation dot1q <vlan-id> command is not necessary”

imageClick to enlarge

Output of “show running-config” of G0/0 Interface

imageClick to enlarge

LAYER 3 (MULTILAYER) SWITCHES

ICON APPEARANCE

imageClick to enlarge

  • A MULTILAYER SWITCH is capable of both SWITCHING and ROUTING
  • It is LAYER 3 AWARE
  • You can assign IP Addresses to its L3 Virtual Interface, 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

imageClick to enlarge

SW2 Replaced with a Layer 3 Switch

Multi-VLAN connections to R1 removed and replaced with a point-to-point Layer 3 connection

imageClick to enlarge

  • SVIs (Switch Virtual Interfaces) are the virtual interfaces you can assign IP addresses to in a MULTILAYER SWITCH.
  • Configure each HOST to use the SVI (NOT the ROUTER R1) 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.

imageClick to enlarge

imageClick to enlarge

Clearing R1 configuration to set to work with the Layer 3 Point-to-Point connection

imageClick to enlarge

#no interface <sub-interface id> : removes the VLAN interface

#default interface g0/0 : resets the g0/0 interface to it’s default settings

Then configure the default R1 G0/0 interface’s to IP address : 192.168.1.194 (as per the network diagram)

Configuration of SW2 to use SVI and the Layer 3 Point-to-Point connection with R1

imageClick to enlarge

“default interface <interface-id>” : resets settings on specified interface to defaults

“ip routing” : IMPORTANT command to enable Layer 3 routing on the SWITCH

“no switchport” : configures the interface from a Layer 2 Switchport to a Layer 3 “routed port”

The sets the Default Route to R1 (192.168.1.194) so that all traffic leaving the network gets routed through R1’s Gateway of Last Resort (aka The Default Gateway)

imageClick to enlarge

imageClick to enlarge

SVI CONFIGURATION ON SW2 (Virtual LAYER 3 ROUTING INTERFACES)

imageClick to enlarge

SVIs are shut down by default, so remember to use “no shutdown”

imageClick to enlarge

Creating an unknown SVI (VLAN 40) and the Status/Protocol is “down/down”

What are the conditions for a SVI to be “up/up” ?

  • The VLAN must exist on the SWITCH
  • The SWITCH 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
  • The VLAN must not be shutdown (you can use the “shutdown” command to disable a VLAN)
  • The SVI must not be shutdown (SVIs are disabled, by default)

imageClick to enlarge

The VLAN trunk has been successfully replaced by an Layer 3 SWITCH SVI.

All hosts should be able to connect with each other (tested with “ping”) as well as reach the external internet (via the Cloud symbol attached to R1)

PreviousVLANs - Part 2
NextDTP / VTP