[nsp] multicast questions

[Danny McPherson]

On May 7, 2004, at 4:17 PM, Charles Sprickman wrote:
>
> Hmmm.  That certainly sounds like it's not only supported, but is the
> preferred method.
>
> Anyone have good pointers to Windows + Multicast?  I understand the 
> basics
> here, but I'm completely lost on the windows side.
>
> It certainly looks like there's not much more on the Cisco than putting
> "ip pim sparse-dense-mode" on each interface.  I don't *think* I need 
> an
> RP, but that doesn't look too tough to setup either.

Note that while some may recommend "spare-dense", I'd suggest
you use caution.  "sparse-dense" is fine if you've got a pretty
darn dense set of receivers and the flooding isn't going to be
an issue.

However, issues arise if you've got a sparse group (especially a
high-bandwidth one) and your RP dies, goes away, whatever; a
la dense!

Given, tricks such as Anycast RPs are great for helping with
this redundancy issue - but if you need an RP and the
configuration is going to be fairly static, I suggest you consider
sparse mode only and statically map your RP addresses.

There are other implications that should be considered as well,
e.g., broken or infected hosts flooding packets to multicast
groups for which no RP exists; i.e., now dense mode groups.

While YMMV, I suggest folks enabling multicast do a bit
more than configure a few CLI options assume things will
be dandy.

Then again...  I learned a great deal about multicast by
deploying it, and it was all mostly fun -- until some starting
selling it :-)

-danny