Why use layer 3 capable Ethernet cards in a router?

Discussion in 'Cisco' started by Farouq, Mar 22, 2007.

  1. Farouq

    Farouq Guest

    We have an MPLS network and have installed 3825 routers at each of the
    locations.

    Video conferencing, voice and data traffic is presented to seperate
    Ethernet interfaces on the routers Ethernet interfaces. I have two
    modules installed:

    NM-2FE2W-V2

    The video, voice and data traffic is seperated into different VLANs.

    Now I have been asked to replace the above Ethernet cards because they
    are not layer 3 capable.

    Having searched the Cisco website I've found the following layer 3
    module:

    HWIC-2FE

    The above is layer 3 capable and you can install upto two of these in
    a 3825 router.

    My question is why would we need the layer 3 cards? The VLAN tagging
    is layer 2 anyway. Routing between VLANs, should this be required, can
    be done by the router.

    Can someone please clarify?

    Thanks.

    Farouq
    Farouq, Mar 22, 2007
    #1
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  2. "Farouq" <> wrote in message
    news:...
    > We have an MPLS network and have installed 3825 routers at each of the
    > locations.
    >
    > Video conferencing, voice and data traffic is presented to seperate
    > Ethernet interfaces on the routers Ethernet interfaces. I have two
    > modules installed:
    >
    > NM-2FE2W-V2
    >
    > The video, voice and data traffic is seperated into different VLANs.
    >
    > Now I have been asked to replace the above Ethernet cards because they
    > are not layer 3 capable.
    >
    > Having searched the Cisco website I've found the following layer 3
    > module:
    >
    > HWIC-2FE
    >
    > The above is layer 3 capable and you can install upto two of these in
    > a 3825 router.
    >
    > My question is why would we need the layer 3 cards? The VLAN tagging
    > is layer 2 anyway. Routing between VLANs, should this be required, can
    > be done by the router.
    >
    > Can someone please clarify?


    Not many switch ports are layer-3 ... obviously.
    If your need is layer-2, there is no immediate need for layer-3 ports.
    The "big" difference are the capability to enter "no switchport" which then
    turns it into a router port i.e. layer-3
    So the need for router ports are the question here, and keep in mind that
    QoS is different in layer-3.

    HTH
    Martin

    >
    > Thanks.
    >
    > Farouq
    >
    Martin Bilgrav, Mar 25, 2007
    #2
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