• Router with Separate Interfaces
  • Routers configure each interface to a different VLAN
  • Less likely to suffer congested lines, but more likely to run out of interfaces
• Router on a Stick
  • Traffic for multiple VLANs are trunked on a single interface
  • Each VLAN is assigned to a virtual sub-interface
  • More likely to suffer congested lines
  • The dot1q tag in a Frame specifies the sub-interface
• Layer 3 Switch
  • Takes over some Layer 3 functions of a router, such as local VLAN/Subnet switching
  • Intra-campus traffic routed on switch backplane, reducing hops to external router
  • Router may still be needed for WAN connected and other services
• 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

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