Build switched network with multicast

Discussion in 'Cisco' started by spo83_work@hotmail.com, Dec 26, 2007.

  1. Guest

    Hi,
    I need to configure a switched network, based of some catalyst 3750
    (ios12.2(40)) in an extended star topology with a basic multicast PIM
    configuration in sparse-dense mode.
    I've read something about but I've never do it.
    Does anybody have experience setting up multicast using a Catalyst
    Layer3 switch?
    Thanks in advance.
    Regards
    Andrea
    , Dec 26, 2007
    #1
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  2. stephen Guest

    <> wrote in message
    news:...
    > Hi,
    > I need to configure a switched network, based of some catalyst 3750
    > (ios12.2(40)) in an extended star topology with a basic multicast PIM
    > configuration in sparse-dense mode.


    i have run this, but only sparse only mode, on Cat 3560s (which are 3750s
    without the stack connections)

    note that sparse / dense is a cisco enhancement over PIM v2 (as is AutoRP),
    and if you want to interwork with other equipment i suggest you use sparse
    mode only.

    the way my system is set is with 2 BSRs, and multiple RPs.

    1 peculiarity of the 3560 / 3750 is you need to set the SDM prefer command
    correctly (AFAIR we use "sdm prefer routing" to handle the routing table we
    need).

    Even then you only have TCAM for 1k multicast hardware entries - since every
    active flow can use 2 or more hardware entries this might limit what you do.

    If you are in a campus setup then you could play around with the rate
    threshold and make the switches run on the RP and (*, g) entries, but it may
    hit the RP performance.

    exceeding h/w tcam entries will silently fail over to software forwarding,
    but performance drops like a stone (saw this with unicast and the manuals
    claim the same for multicast)....

    > I've read something about but I've never do it.
    > Does anybody have experience setting up multicast using a Catalyst
    > Layer3 switch?


    just turn on multicast globally, and on each interface.

    make sure you are running a good stable unicast protocol, as PIM uses this
    to do address checks. We use OSPF, again for interworking.

    life gets a bit more complicated if you add L3 equal cost multipath - so
    avoid it if you can.

    there are some limitations in the rel notes (last code i saw was 12.2.40SE -
    you need enhanced to do PIM) - we had to upgrade to support PIM & VRFs on
    the same box.

    finally - monitoring tools are not fantastic, and multicast can generate
    lots of complications for debugging.

    > Thanks in advance.
    > Regards
    > Andrea

    --
    Regards

    - replace xyz with ntl
    stephen, Dec 26, 2007
    #2
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  3. Guest

    >" just turn on multicast globally, and on each interface.
    >
    > make sure you are running a good stable unicast protocol, as PIM uses this
    > to do address checks. We use OSPF, again for interworking.
    >
    > life gets a bit more complicated if you add L3 equal cost multipath - so
    > avoid it if you can.
    >
    > there are some limitations in the rel notes (last code i saw was 12.2.40SE -
    > you need enhanced to do PIM) - we had to upgrade to support PIM & VRFs on
    > the same box.
    >
    > finally - monitoring tools are not fantastic, and multicast can generate
    > lots of complications for debugging."


    Thanks Stephen!
    so I've just another one doubt. The multicast routing is between Vlans
    or I need to configure
    some ports in "no switchport" mode and with an ip address to allow
    that?
    Thank you so much.
    Regards.
    Andrea
    , Dec 28, 2007
    #3
  4. stephen Guest

    <> wrote in message
    news:...
    > >" just turn on multicast globally, and on each interface.
    > >
    > > make sure you are running a good stable unicast protocol, as PIM uses

    this
    > > to do address checks. We use OSPF, again for interworking.
    > >
    > > life gets a bit more complicated if you add L3 equal cost multipath - so
    > > avoid it if you can.
    > >
    > > there are some limitations in the rel notes (last code i saw was

    12.2.40SE -
    > > you need enhanced to do PIM) - we had to upgrade to support PIM & VRFs

    on
    > > the same box.
    > >
    > > finally - monitoring tools are not fantastic, and multicast can generate
    > > lots of complications for debugging."

    >
    > Thanks Stephen!
    > so I've just another one doubt. The multicast routing is between Vlans
    > or I need to configure
    > some ports in "no switchport" mode and with an ip address to allow
    > that?


    you can mix and match routed interfaces with "no switchport" and multicast
    routing on VLAN interfaces - both seem to work well.

    1 complication we have had is that there are other manufacturers kit on this
    network.
    Cisco have a multicast to 224.0.1.40 (AFAIR) set up as soon as you use PIM -
    this is part of the autoRP scheme, and i havent found a way to turn it off.

    we get issues with this since we have a resilient topology, and the autoRP
    m/cast gets to the other kit, then gets pushed back. On some of the Cisco
    boxes we then get "invalid RP join" errors filling the log.

    you should be able to filter this using the multicast boundary feature to
    stop it causing problems

    other than that it has been relatively simple - most of our effort has gone
    into QoS, q handling (as the Cat 3560 3750s are wierd) and OSPF tuning.

    > Thank you so much.
    > Regards.
    > Andrea

    --
    Regards

    - replace xyz with ntl
    stephen, Dec 28, 2007
    #4
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