Well, I had a chance to do a little testing on this situation.
It seems what Cisco really meant to say was, "physical
multicasting" or "physical broadcasting". PIM specifically had
nothing at all to do with it.
When I set up the frame cloud to test this, it was not readily
apparent my test was less than valid. It was only when I went
to the "sh frame map" command that I saw this:
2522#sh fram map
Serial0.1 (up): point-to-point dlci, dlci 100(0x64,0x1840),
broadcast
status defined, active
It then immediately dawned on me what the problem was. I
proceeded to undo all of my frame configs until they all read
similar to this:
2511#sh fram map
Serial0.4 (up): ip 3.0.0.1 dlci 110(0x6E,0x18E0), static,
CISCO, status defined, active
Serial0.4 (up): ip 20.0.0.1 dlci 120(0x78,0x1C80), static,
CISCO, status defined, active
Serial0.4 (up): ip 22.0.0.1 dlci 130(0x82,0x2020), static,
CISCO, status defined, active
Note that I made the conversion from auto frame to static
mappings. In the process, I conveniently left off the
keyword "broadcast" on the frame-relay static mappings. Here
is what the EIGRP hellos looked like prior to static mapping:
02:05:52: EIGRP: Received HELLO on Serial0.4 nbr 22.0.0.1
02:05:52: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
peerQ un/rely 0/
1
02:05:52: EIGRP: Sending UPDATE on Serial0.4 nbr 22.0.0.1,
retry 3, RTO 5000
02:05:52: AS 1, Flags 0x1, Seq 44/0 idbQ 0/0 iidbQ un/rely
0/0 peerQ un/rely 0
/1 serno 11-13
02:05:57: EIGRP: Received HELLO on Serial0.4 nbr 22.0.0.1
02:05:57: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
peerQ un/rely 0/
1
02:05:57: EIGRP: Sending UPDATE on Serial0.4 nbr 22.0.0.1,
retry 4, RTO 5000
02:05:57: AS 1, Flags 0x1, Seq 44/0 idbQ 0/0 iidbQ un/rely
0/0 peerQ un/rely 0
/1 serno 11-13
02:06:01: EIGRP: Received HELLO on Serial0.4 nbr 22.0.0.1
02:06:01: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
peerQ un/rely 0/
1
If you note the timestamps, they are approximately every five
seconds. Here is what it looks like with the static mapping
statements and the *broadcast* keyword removed from the static
mapping statements:
2522#
03:21:15: EIGRP: Sending HELLO on Serial0
03:21:15: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
03:21:45: EIGRP: Received HELLO on Serial0 nbr 22.0.0.2
03:21:45: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0
03:22:07: EIGRP: Sending HELLO on Serial0
03:22:07: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0
03:22:40: EIGRP: Received HELLO on Serial0 nbr 22.0.0.2
03:22:40: AS 1, Flags 0x0, Seq 0/0 idbQ 0/0
You will note that send/receive hellos are approximately one
minute apart. It would appear that instead of making matters
clearer by just stating the obvious, Cisco chose instead to
state the correct information in a somewhat convoluted and less
than clear manner:-)
As far as turning off multicasting capability on the interface,
you definitely lose it when you lose broadcast capability since
they both share the same bit to signify a broadcast packet(bit
8 going from left to right of the MAC address). I guess their
thinking was that since they were discussing EIGRP and EIGRP
timer adjustments, it was understood that the underlying method
of layer 2 transmission would be via multicasting.
Final note. I did find an interesting little command that may
achieve what Chuck was trying to do. The command is as follows:
ip multicast rate-limit in 0
and
ip multicast rate-limit out 0
The intent of this command was to rate limit or throttle
multicast streams such as video (IPTV) or audio (Real Audio) by
ensuring that a multicast stream did not saturate a link.
Based upon quick testing I did, It did not appear to affect any
EIGRP multicast related traffic which leads me to believe it is
possibly filtering on UDP based multicast.
v/r,
Paul Werner
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---- On Sun, 5 Aug 2001, Leigh Anne Chisholm ([EMAIL PROTECTED])
wrote:
> Here's the link I got the quote from:
>
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/
122cgcr/fipr
> _c/ipcprt2/1cfeigrp.htm#xtocid2271313
>
> Check out the third paragraph for the quote.
>
>
> -- Leigh Anne
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On
Behalf Of
> Paul Werner
> Sent: Sunday, August 05, 2001 12:37 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Subject: EIGRP's interpretation of NBMA
and "disabling
> [7:14934]
>
>
> I read this a different way. I interpreted the author's
> discussion of "physical multicasting" to mean multicast
> routing. Multicast routing can be turned on and off
individual
> interfaces. Moreoever, when you get to the discussion on CCO
> about optimizing multicast routing, there is this section:
>
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios11/c
> book/ciproute.htm#xtocid16743149
>
> I agree the wording could be better. As far as disabling
> multicast from an interface, my gut reaction would be, why
> would you want to?
>
> HTH,
>
> Paul Werner
>
>
>
> > On Cisco's site, I've been searching for information as to
> when the
> > hello
> > interval is set to 5 seconds and when it is set to 60
> seconds. Hellos
> > are
> > sent every 5 seconds except on low-speed, NBMA media. Low-
> speed is
> > defined
> > as 1.544 Mbps and under. No problems there.
> >
> > What I don't understand is this statement:
> >
> > "Note that for the purposes of EIGRP, Frame Relay and
Switched
> > Multimegabit
> > Data Service (SMDS) networks may or may not be considered to
> be NBMA.
> > These
> > networks are considered NBMA if the interface has not been
> configured to
> > use
> > physical multicasting; otherwise they are not considered
> NBMA."
> >
> > How can you configure an interface not to use multicasting?
> This is
> > something I haven't come across how to do yet. Is this
> configuring
> > EIGRP
> > multicasts to use unicasts (I think I saw something like
that
> last night
> > but
> > I was too tired to comprehend it or even remember where I
saw
> it).
> >
> >
> > -- Leigh Anne
Message Posted at:
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