vlan and multicast

Discussion in 'Cisco' started by dkhrone, Nov 23, 2007.

  1. dkhrone

    dkhrone Guest

    Hello

    Let a switch with 3 port based vlans, vlan id 1, 2 and 3 with IGMP
    snooping (basic layer 2 network)
    On vlan 1 and 2 there are video multicast sources. A video monitor
    connected on vlan 3 should be able to receive both multicast stream.
    If the port where video monitor is connected belong to vlan 1, 2 and 3,
    could the video monitor receive both streams after IGMP registration ?
    What are the pros and cons ?
    Thanks for your help.

    Another question : are source address of multicast frames translated
    with NAT ? If yes how to identify the source of the multicast once gone
    through the NAT ?

    dk
     
    dkhrone, Nov 23, 2007
    #1
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  2. dkhrone

    stephen Guest

    <dkhrone> wrote in message news:47474735$0$28484$...
    > Hello
    >
    > Let a switch with 3 port based vlans, vlan id 1, 2 and 3 with IGMP
    > snooping (basic layer 2 network)
    > On vlan 1 and 2 there are video multicast sources. A video monitor
    > connected on vlan 3 should be able to receive both multicast stream.
    > If the port where video monitor is connected belong to vlan 1, 2 and 3,
    > could the video monitor receive both streams after IGMP registration ?


    homework time?

    IGMP is about devices telling the local router interface what groups they
    want.

    multicast routing is then needed to pass multicast packets between them

    So - not unless there is a L3 box somewhere to act as a multicast router
    (which is probably what would handle the IGMP stuff).

    and on some Cisco boxes multicast requires an additional licence - eg if the
    VLAN switch is a Cat 3560 / 3750 then it will need whatever Cisco are
    calling an enhanced image this week.

    > What are the pros and cons ?


    er - it doesnt work unless you add more functionality?

    > Thanks for your help.
    >
    > Another question : are source address of multicast frames translated
    > with NAT ?


    not if they dont pass thru a NAT function :)

    If yes how to identify the source of the multicast once gone
    > through the NAT ?
    >
    > dk
    >

    --
    Regards

    - replace xyz with ntl
     
    stephen, Nov 23, 2007
    #2
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  3. dkhrone

    dkhrone Guest

    On 2007-11-23 22:55:02 +0100, "stephen" <> said:

    > <dkhrone> wrote in message news:47474735$0$28484$...
    >> Hello
    >>
    >> Let a switch with 3 port based vlans, vlan id 1, 2 and 3 with IGMP
    >> snooping (basic layer 2 network)
    >> On vlan 1 and 2 there are video multicast sources. A video monitor
    >> connected on vlan 3 should be able to receive both multicast stream.
    >> If the port where video monitor is connected belong to vlan 1, 2 and 3,
    >> could the video monitor receive both streams after IGMP registration ?

    >
    > homework time?


    >
    >

    not really, I plan to buy a used ethernet switch that could deals with
    vlan (port based) and IGMP but I prefer to be sure I will the get what
    I need.
    On 2 different VLAN, I have two stations with USB webcam that multicast
    video stream. I want to monitor these streams from a 3rd vlan.
    Because a VLAN define a broadcast domain, I was thinking that if the
    port where the monitoring station is connected could be in several
    VLANs (1 2 and 3) at the same time, it could receive stream of vlan 1
    after IGMP registration and/or stream from VLAN 2 after another IGMP
    registration.
    Adding a layer 3 box may be more expensive.

    > IGMP is about devices telling the local router interface what groups they
    > want.
    >
    > multicast routing is then needed to pass multicast packets between them
    >
    > So - not unless there is a L3 box somewhere to act as a multicast router
    > (which is probably what would handle the IGMP stuff).
    >
    > and on some Cisco boxes multicast requires an additional licence - eg if the
    > VLAN switch is a Cat 3560 / 3750 then it will need whatever Cisco are
    > calling an enhanced image this week.
    >
    >> What are the pros and cons ?

    >
    > er - it doesnt work unless you add more functionality?
    >
    >> Thanks for your help.
    >>
    >> Another question : are source address of multicast frames translated
    >> with NAT ?

    >
    > not if they dont pass thru a NAT function :)
    >
    > If yes how to identify the source of the multicast once gone
    >> through the NAT ?
    >>
    >> dk
    >>

    > --
    > Regards
    >
    > - replace xyz with ntl


    Thanks for your help.
     
    dkhrone, Nov 24, 2007
    #3
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