CCNA 3.4.a: Router on a Stick


Router on a stick is a means of connecting to two or more subnets via a single physical Layer 3 interface using subinterfaces.


Study Notes:

  • Router on a stick, a.k.a. One armed router or Stub router
  • Router on a stick is useful when needing to connect to multiple subnets from a single router port
  • Typically this is when you have multiple LAN networks on a router
  • The router interface is configured for layer3 using subinterfaces
  • The switch interface going to the router is a trunk port that tags the vlans you want to allow to the router
  • A native vlan is used on the trunk port to tag any untagged packets
  • The switch interfaces going to the PCs are access vlans with the appropriate vlan configured on them


PacketTracer Lab: CCNA-3.4.a-Router-on-a-stick.pkt

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  1. Gwendoline Nubila
    Gwendoline Nubila
    February 26, 2019 at 5:08 am

    on the switch config for int fa0/1, the command switchport native vlan 678 does not work.I used switchport trunk native vlan 678 and it went through.

    • Joe Barger (CCNP/CCDP)
      Joe Barger (CCNP/CCDP) • Post Author •
      February 26, 2019 at 8:56 pm

      That’s interesting. Thanks for pointing that out. I’m running PacketTracer This version accepts the command switchport native vlan 678, but it then changes the running-config to switchport trunk native vlan 678. It appears the forums discuss this as well – I’ve updated the labs to include trunk in the command. Thanks!

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