SPAN and RSPAN with VLAN source?

Discussion in 'Cisco' started by joeblow, Feb 17, 2005.

  1. joeblow

    joeblow Guest

    I've got six 3550-24 switches with three vlans vlan_a vlan_b and vlan_c
    set up across all six 3550s. They are interconnected with gigabit fiber.

    I want to monitor vlan_a with a fluke lanmeter. I'm plugging the lanmeter
    into fastethernet 0/24 on the switch in the lab (which is not the cluster
    master).

    Can I get away with:

    SW_LAB # mon sess 1 source vlan 2 rx

    (2 is the vlan_a vlan number)

    Or do I need to set up rspan on the other 5 3550's as well to see all
    vlan_a traffic?

    Thanks!
     
    joeblow, Feb 17, 2005
    #1
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  2. :I've got six 3550-24 switches with three vlans vlan_a vlan_b and vlan_c
    :set up across all six 3550s. They are interconnected with gigabit fiber.

    :I want to monitor vlan_a with a fluke lanmeter. I'm plugging the lanmeter
    :into fastethernet 0/24 on the switch in the lab (which is not the cluster
    :master).

    :Can I get away with:

    :SW_LAB # mon sess 1 source vlan 2 rx

    :Or do I need to set up rspan on the other 5 3550's as well to see all
    :vlan_a traffic?

    You mention that the 3550's are connected via gigabit fibre, but you
    din't mention the magic word "gigastack". I was looking at the
    documentation just yesterday; as best I can tell, 3550's that are
    connected via plain GBICs act as independant devices; putting them into
    a "cluster" just makes administration easier. When you use "gigastack"
    GBICs, though (easy to tell, there is two connections for each
    gigastack GBIC instead of a single connection) then the 3550's are
    truly stacked together.

    If stacked, you could expect to be able to span all of the vlan 2
    traffic, but if merely cross-connected then you would only see the vlan
    2 traffic that needed to go as far as the spanning switch in order to be
    handled.
     
    Walter Roberson, Feb 17, 2005
    #2
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  3. Hi..

    First of all understand.. wht stacking is..and how it is different from
    cascading.. When u stack 3550's it just extends the switching fabric
    across multiple switches.. so it still acts as a single switch.. When u
    cascade two switches.. then u hv to enable trunking between two
    switches.. considering u hv multiple VLANS...

    U need RSPAN when u hv trunking enabled between two switches.. ( or if
    they are cascaded) but this is not the case in stacking .. hence RSPAN
    is not needed..

    The configuration mentioned should work.. Also i hope u must hv
    specified the second command to specify destation as the port on which
    sniffer is connected...


    ~ Jay :eek:)
     
    Jayesh Sharma, Feb 17, 2005
    #3
  4. joeblow

    thrill5 Guest

    The Gigastack connector provides the same function as a GBIC. The
    difference is that the gigastack connector allows you to use only one GBIC
    connector to provide connections to two switches for fault tolerance. The
    tradeoff is that when you use Gigastack connectors, each of the 2
    connections run at HALF-DUPLEX instead of full-duplex. Each GBIC slot
    provides 2 Gig of bandwidth, (1 gig for transmit and 1 gig for receive) so
    when you run the gigastack the two ports run in half-duplex mode. With
    half-duplex, transmit and receive share 1 Gig of bandwidth.

    Scott
     
    thrill5, Feb 21, 2005
    #4
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