Re: CGMP vs IGMP Snooping ?

From: Joel W. Ekis (jekis@xxxxxxxxx)
Date: Tue Mar 28 2000 - 09:54:40 GMT-3


   
Right, on the "still extensible" C5k <g>, you would set:
        set multicast router <mod/port> (optional to statically
 define the port)
        set cgmp enable

To view the results:
        show multicast group cgmp

The router would need:
        interface fa0/0
          ip pim sparse-dense-mode
          ip cgmp

The function of sparse-dense mode works like the following:

If you do not define an RP for a multicast address, operate in dense mode for t
hat address.
If you define an RP for an address, operate in sparse mode.

Defining the RP is best done with Cisco's automatic discovery mechanism.

ip pim send-rp-announce ethernet0 scope 16 (announce that e0 is a C-RP for
 all multicast groups)
ip pim send-rp-discovery scope 16 (inform all multicast routers t
hat an RP is available)

By adding the keyword "rp-list", you can control which IP addresses are valid R
P's. By adding the keyword "group-list", you can control the range of multicas
t addresses for which the router will act as the RP. The lists are formed from
 IP access lists.

<ad follows>
To books I found extremely useful are from Cisco Press on these two subjects:
        CCIE Professional Development : Cisco LAN Switching
        by Kennedy Clark, Kevin Hamilton ISBN: 1578700949

        Developing IP Multicast Networks
        by Beau Williamson ISBN: 1578700779

Joel

At 10:14 PM 3/27/2000 -0500, clou@ebnetworks.com wrote:
>
>Joel,
>
>I just looked up the CD and it stated "... CGMP should be
>enabled only on routers connected to Catalyst switches..."
>(IOS 12.0). Another word, If I configure IP multicast
>between a router and a "yesterday's switch" Cat5500 <g>,
>I still need "ip cgmp" for the router and "set cgmp enable"
>for the 5500, is it correct?
>
>Also, need to confirm that if I configure sparse-desnse
>mode on an interface, do I still need to specify RP-address
>for a multicast group? Can any one confirm this, please?
>
>Thanks,
>
>Chi
>



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