Tunnels in Labs

Labs "Do’s and Don’ts" says that we cant add or change ip address, but in solution you often add new subnets for tunnell interface.

Also SW1 is SWITCH, but you build tunnel frim it, in spite of Release Notes for IOS says "(Catalyst 3750 or 3560 switches and Cisco EtherSwitch service modules) The switch does not support tunnel interfaces for unicast routed traffic. Only Distance Vector Multicast Routing Protocol (DVMRP) tunnel interfaces are supported for multicast routing."


  • Although I did not search release notes but yes tunnel interface in switch1 does not come up.
  • I can confirm that Generic Routing Encapsulation (GRE) tunnels are not supported on the Cisco Catalyst 3550 Switch. Even though the CLI commands are there to configure the GRE, it is not officially supported.
    I therefore doubt whether this could possibly be required in a CCIE lab environment as they do follow TAC best pratices.

    Despite this it does come up in this case...

    Rack1SW1#sh int tunnel 1
    Tunnel1 is up, line protocol is up
    Hardware is Tunnel
    Internet address is
    MTU 1514 bytes, BW 100 Kbit, DLY 50000 usec,
    reliability 255/255, txload 1/255, rxload 1/255
    Encapsulation TUNNEL, loopback not set
    Keepalive not set
    Tunnel source (Vlan72), destination
    Tunnel protocol/transport GRE/IP, key disabled, sequencing <truncated>
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