Native VLAN - usage on multiply physical interfaces?

Discussion in 'Cisco' started by DaZZa, Apr 12, 2005.

  1. DaZZa

    DaZZa Guest


    I have a situation which is somewhat stumping me, and I'm looking for
    the voice of wisdom from someone who maybe understands the concept of
    the "native" VLAN for trunking better than I do.

    I have a single router - a 3745 - which connects to a number of
    switches, and from there on to other devices. It has two gigabit
    iterfaces & 4 fast ethernet interfaces, and is running the Enterprise
    base feature set IOS.

    Connected to each gigabit interface, I have a 3500 series switch which
    each carry a different set of vlans via trunk links.

    I've configured a "native" vlan on a sub-interface for each gigabit
    interface, as well as other sub interfaces for the relavent vlans.

    What I want to do is use one subnet range for the cascaded switches
    management vlan, or vlan1. I have configured the native interface on the
    first interface with an IP address and subnet range, and all the
    cascaded switches work fine.

    However, when I configure the second gigabit interface with a native
    interface with the same vlan ID as the first, I can't get any IP
    connectivity from the native vlan on the cascaded switches on the range.

    show vlans gives me this

    Core>sh vlans

    Virtual LAN ID: 1 (IEEE 802.1Q Encapsulation)

    vLAN Trunk Interfaces: GigabitEthernet2/0.1

    This is configured as native Vlan for the following interface(s) :

    Protocols Configured: Address: Received: Transmitted:
    IP 9096282 989405265

    My understanding of how this works is that being the "native" VLAN is
    the same ID on each downlink switch, all I should have to do is assign
    an IP address in the appropriate range, set a default gateway and all
    should work. However, this doesn't work - and I don't know why.

    Can anyone shed some light? Is what I want to do even possible?


    DaZZa, Apr 12, 2005
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