ROAS

• A Router on a Stick Inter-VLAN Routing solution creates sub-interfaces within a single interface on a router to Trunk traffic from different VLANs over a single link between a Switch and a Router
  • Each VLAN is configured to a unique sub-interface
    • The sub-interface number does not have to match the VLAN ID
      • e.g., VLAN 20 can be on interface G0/0.10
    • The 802.1Q tag in an frame identifies the sub-interface
  • The native VLAN can be configured on the main-interface
• Configuration
  • Router: Create the sub interface on the trunking interface
    • config# int <interface>.<VLAN ID>
      • That is, config# int g0/1.10
  • Router: Configure the sub interface to operate on a specific VLAN
    • config-subif# encap dot1q <vlan ID>
    • If the sub-interface belongs to the native VLAN, don't forget to add native at the end
  • Router: No shut the main interface to enable all sub-interfaces
    • config-if# no shut
  • Switch: Configure interface to function as a trunk port, with the allowed VLANs
    • config-if# switchport mode trunk
    • config-if# swithcport trunk allowed vlan <VLAN IDs separated by commas>

Metadata

OSI or TCP/IP Layer

CCNA Exam Topic

Contributors

Sources