From: ccie2be (ccie2be@nyc.rr.com)
Date: Mon Aug 09 2004 - 11:54:06 GMT-3
Ty,
What makes you so sure the app is running in sparse mode?
Does the app somehow specify that it wants to in sparse mode or does the app
just send packet out to a certain mcast address?
Could you post the output of the show ip pim rp mapping and show ip mroute
x.x.x.x commands?
Personally, I believe your mistaken. Either there is an rp and you don't
realize that or the app is running dense mode.
----- Original Message -----
From: tycampbell@comcast.net
To: ccie2be ; Lord, Chris ; ccielab@groupstudy.com
Sent: Monday, August 09, 2004 10:37 AM
Subject: Re: PIM-SM
I believe that the assumption that "If a pim router knows of a rp for the
group, the group operates in sparse mode, otherwise it operates in dense
mode." is incorrect.
If I understand what you are saying is correct, then I would be led to
believe that in sparse mode, an rp must be defined
I have an application running on a network. The application is running in
sparse mode without an rp. This application is setup on a layer 3 switch and
is running perfectly. Therefore, at least for this case, I am running sparse
mode without an rp. I did not want dense mode because of extra traffic. This
is the only mulicast application running on this particular network, so I am
not to concerned about it. The applcation is only used during off hours for OS
images
Dense mode is not specified, so therefore the application is not running in
dense mode. The rp does not always determine that the application only runs in
sparse mode. If it does always need to be specified for dense mode, then the
applcation should not be running at all
-------------- Original message --------------
> Chris,
>
> Your question can be restated as "What determines whether a mcast
operates
> in Dense mode or Sparse mode?"
>
> Many people. it seems, have the misperception that the mode entered on
the
> interface determines the mode in which the mcast group operates.
>
> THIS IS WRONG !!!
>
> Only one thing determines if a mcast group operates in sparse or dense
mode
> and that is if an RP exists for the group and the given router knows
where
> that rp is. If a pim router knows of a rp for the group, the group
operates
> in sparse mode, otherwise it operates in dense mode.
>
> But, this does lead to an interesting question - a question I don't know
the
> answer for.
>
> Suppose in a mcast domain all interface! s are configured with ip pim
> sparse-mode. And, there's an rp for some mcast groups but not for
others.
> What happens with the groups that operate in dense mode? Will they run
> properly or will they experience problems? And, if so, what type of
> problems?
>
>
> ----- Original Message -----
> From: "Lord, Chris"
> To:
> Sent: Monday, August 09, 2004 5:00 AM
> Subject: PIM-SM
>
>
> > Please can someone help me to understand this......
> >
> > I have three routers:
> >
> > e0-R1-s0---s0-R2-s1---s0-R3-e0
> >
> > PIM-SM is configured on all of the interfaces.
> >
> > R1-e0 has an ip igmp join for three groups 224.1.1.1, 224.2.2.2 and
> 224.3.3.3
> >
> > R1 and R2 use R3-s0 as the RP for groups 224.1.1.1 and 224.2.2.2.
Ther! e is
> no RP configured for 224.3.3.3
> >
> &g t; Results - I can ping 224.1.1.1 and 224.2.2.2 from any router as
expected.
> What I didn't expect is that I can also ping 224.3.3.3 from R1 and R2
(but
> not R3). When I look in ip mroute for 224.3.3.3 it is operating in DM on
R1
> and R2 even though only PIM-SM is configured. Why is this?
> >
> > TIA.
> >
> > Chris.
> >
> >
> >
> >
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