From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Tue Oct 17 2006 - 01:46:54 ART
Hi Dan,
It only needs to apply to the device that is delivering the
directed broadcast to the directly connected segment, which in this case
is interface "3". For example if your connected subnet is 10.0.0.0/24
the directed broadcast address would be 10.0.0.255. However for devices
in the transit path they don't necessarily know that 10.0.0.255 is a
broadcast address. After all if the final destination segment was
10.0.0.0/23 then 10.0.0.255 would be a valid host address.
Take a look at this excerpt from IEWB-RS for an example:
http://www.internetworkexpert.com/downloads/mcast-helper.pdf
Add this to R6 to make it generate multicast traffic to test the
configuration:
ip sla monitor 1
type udpEcho dest-ipaddr 255.255.255.255 dest-port 3434 source-ipaddr
174.1.26.6 source-port 3434 control disable
timeout 0
frequency 5
ip sla monitor schedule 1 start-time now
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> dan.bliss@gmail.com
> Sent: Monday, October 16, 2006 10:46 PM
> To: ccielab@groupstudy.com
> Subject: Multicast helper clarification
>
> All,
>
>
> Ok, I have searched the archives and did not find a "definitive"
answer
> for the following questions and would appreciate your assistance:
>
> Where do we "NEED" the "ip directed-broadcast" statements when using
> multicast helper? And does it matter if the source is a subnet only
> broadcast or all hosts broadcast? The cisco documentation is very
vague
> and even just plain wrong in parts.
>
> (some of the following is copied from an archived post, i just
modified it
> to save time)
>
>
> So this is my understanding so far:
>
>
>
>
> | ( ) |
> source |--R1--( Mcast )--R2--| Destination
> | ^ (_____) ^ ^ |
> 1 2 3
>
> ------------------------------------------------------
> The following configuration should go on interface "1"
>
> ip multicast helper-map broadcast 225.5.5.5 100
>
> (where 255.5.5.5 is the multicast address to convert the broadcast to
and
> "100" is an extended access-list that matches the traffic to convert.)
>
>
> The following configuration should go on interface "2"
>
> ip multicast helper-map 225.5.5.5 12.255.255.255 100
>
> (where 255.5.5.5 is the same group as previously referenced,
> 12.255.255.255
> is the directed broadcast address of interface "3", and access-list
100 is
> the same as previously referenced)
>
> Globally we need an acl to match the traffic on R1 and R2
> access-list 100 permit udp any any eq 4000
>
> Globally we need the router to perform the conversion at the process
level
> on R1 and R2
> ip forward-protocol udp 4000
>
------------------------------------------------------------------------
>
>
> So, where does the ip directed-broadcast statement(s) go? Cisco says
point
> 1 and point 3, are they correct?
>
> I have seen it work with it applied only at point 3 in the diagram
only
> which makes the most sense to me.
>
>
> Thanks in advance,
>
> Dan Bliss
>
>
> P.S. Thanks to Pierre-Alex for answering my last multicast question.
Much
> appreciated.
>
>
This archive was generated by hypermail 2.1.4 : Wed Nov 01 2006 - 07:29:05 ART