From: Brian (shotcaller30@xxxxxxxxxxx)
Date: Tue Nov 14 2000 - 14:47:08 GMT-3
Well I don't believe the pruning is causing the problem. Try setting up
between three routers connected by serial links without running it over a
multipoint interface in the middle. You can ping from the one edge router
to the other edge router which is the RP and has the join-group statement on
ite Ethernet port. Can anyone explain exactly what pim-nbma mode does,
because it doesn't seem to work in this scenerio?
Thanks
----- Original Message -----
From: Hall, Keith <KHall@greenwichtech.com>
To: <ccielab@groupstudy.com>
Sent: Tuesday, November 14, 2000 9:20 AM
Subject: RE: Repost: Multicast with RP as Spoke
> RE: the lack of ping responses with 225.4.4.4 from r3 or 225.3.3.3 from r4
>
> Jeez - I knew this Q would come up.. see pruning! ;)
>
> Remember that r4 and r3 are distant by a router hop. r4 is not
subscribing
> to 225.3.3.3 and r3 is not subscribing to 225.4.4.4 (and therefore I
believe
> it should be pruned under Sparse Mode PIM behavior - contrasted to Dense
> Mode PIM behavior). The incidental responses received via r2 without any
> 'real multicast source' and any 'real multicast subscriber' present is due
> to proximity; not actual subscription.
>
> r3 ------- r2 ------- r4
> 225.3.3.3 225.2.2.2 225.4.4.4
>
> Also, take a look at the overall design. In more complex scenarios, this
> can be quite a challenge to trace. Multicast pings are a little different
> from a standard unicast ping. 225.4.4.4 is on r4 (the RP). 225.4.4.4 is
> figuratively "at the root of the tree" or "at the head of the waters", so
to
> speak. (This is why I originally asked about the multicast source
> placement.) Bad RP placement can have a very detrimental effect on the
> multicast stream. Multicast implementation is very simple in small
> networks, but can be a real pain in the @#$@ in larger ones. (In fact,
I've
> heard of only partially successful or unstable implementations by other
> internetwork integration groups because of the lack of overall design and
> understanding of PIM mechanisms.)
>
>
> RE: Multicast Example
>
> If I understand correctly, you are able to perform a multicast ping in one
> direction??? Check if the 'broadcast' keyword is on r3...
>
> Yesterday, I made up my own OSPF config to test your scenario. The config
> presented was definitely not a full config (ex. no 'frame-relay
> interface-dlci' command) and I couldn't "cut-and-paste" it directly.
> Judging by the complexity of the original config (route-maps, ODR, and
> demand-circuit, et cetera), I would first try running the multicast script
I
> sent over a simplified, standard OSPF over NBMA config without route-maps
or
> other junk. Pls try this first..
>
>
> Keith T. Hall
> Sr. Network Engineer, Service Provider Accounts
> Greenwich Technology Partners
> 3810 Concorde Parkway, Suite 500
> Chantilly, VA 20151
> (703) 966-1854 Cell
> (703) 222-6465 Office
> (703) 222-6424 Fax
> khall@greenwichtech.com
> http://www.greenwichtech.com
>
>
>
>
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