07-15-2009 06:26 PM - edited 03-06-2019 06:47 AM
I'm attempting to convert broadcast traffic on one lan segment into multicast, route it to another segment and then convert it back to broadcast again.
My problem occurs in the last step when the multicast traffic is not converted back to broadcast. I can see the multicast traffic makes it to the destination lan segment when I use wireshark. The topology is below and configs attached.
b'cast-src(10.71.10.2/24) -> Router1 -> Router2 -> dest-lan(192.168.10.0/24)
Any help would be greatly appreciated.
Solved! Go to Solution.
07-17-2009 12:49 AM
Hello Robert,
on router2 remove
ip igmp join-group 239.3.5.35
under interface f0/1
otherwise traffic is sent to cpu (process switched)
being in pim sparse-dense-mode it should not be necessary
Notice also that the original TTL of the broadcast packet has to be > 1 as explained in usage guidelines of command
ip multicast helper-map
otherwise traffic can be dropped for TTL expired.
you can use the ttl option on the first-hop router to increase the ttl of multicast packets.
This can be helpful but I didn't try this option.
Hope to help
Giuseppe
07-17-2009 12:49 AM
Hello Robert,
on router2 remove
ip igmp join-group 239.3.5.35
under interface f0/1
otherwise traffic is sent to cpu (process switched)
being in pim sparse-dense-mode it should not be necessary
Notice also that the original TTL of the broadcast packet has to be > 1 as explained in usage guidelines of command
ip multicast helper-map
otherwise traffic can be dropped for TTL expired.
you can use the ttl option on the first-hop router to increase the ttl of multicast packets.
This can be helpful but I didn't try this option.
Hope to help
Giuseppe
07-17-2009 03:25 AM
Hi robert
you ned to do the following to get it working
first on both routers
add the follwoing command
ip forward-protocol eq 65535
* In order for incoming traffic to hit the multicast helper-map it must be
processed switched. In order to process switch traffic on a per port basis use
the ip forward-protocol udp
Next:
As R2 has the recieving said
remove the map from the 192.168 interface and keep the ip directed broadcast
apply your helper map in R@ to the interface connected to R1 to make it work as intcoming map
In order to convert a UDP broadcast to a multicast for transit, and then back to a
broadcast for final delivery, as in this scenario, the helper-map must be
configured on both the ingress device and egress device for the traffic flow.
R1 incoming from the source
and R2 incoming from R1
good luck if worked let me know
HTH
07-17-2009 11:20 PM
Thank you. Putting the multicast helper-map command on the input interface of r2 worked.
07-18-2009 03:44 AM
i am glad its working now :)
please rate the helpful post
Thank you
07-18-2009 04:41 AM
Hello Marwan,
you got it the right logic for double conversion is the one you have described (rated as it deserves)
Best Regards
Giuseppe
07-18-2009 04:06 PM
Thank you Giuseppe :)
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