Yes this is exactly what I want to accomplish, but I was not sure if
my setup / understanding was right.

Thanks for the links, actually I started to read those before posting
on the ML.

Any though anyone ?


On Mon, Aug 2, 2010 at 12:07 PM, garry baker <[email protected]> wrote:
>
>
> ' ip multicast helper-map' converts broadcast traffic to multicast traffic
> to be sent across a multicast capable network and then turned back to
> broadcast...
>
> i think you are wanting to change the multicast address and unicast it? not
> sure about that one?
>
> here is more info on ' ip multicast helper-map'
>
> http://blog.ine.com/2008/05/06/understanding-the-ip-multicast-helper-map-command/
> http://www.cisco.com/en/US/docs/ios/ipmulti/command/reference/imc_03.html#wp1058167
>
>
> --
> Garry L. Baker
>
> "There is no 'patch' for stupidity." - www.sqlsecurity.com
>
>
> On Mon, Aug 2, 2010 at 4:30 PM, Johan <[email protected]> wrote:
>>
>> Hi List
>>
>> I have an interesting case, I would like to route mDNS through 2 subnets.
>>
>> The topology is quite simple :
>> Network 172.16.0.0/16
>>
>> HostA-----Fa0/0----R1------Fa0/1----HostB
>> 10.2       10.1             11.1    11.2
>>
>> The communication doesn't have to be bi-directionnal, only from HostA to
>> HostB.
>>
>> As far as I know, mDNS uses 224.0.0.251 and the port UDP 5053.
>>
>> That said, this is a local-link multicast address and it will then no
>> traverse R1.
>>
>> My idea is like this
>>
>> Int fa0/0
>>  ip address 172.16.10.1 255.255.255.0
>>  ip multicast helper-map 224.0.0.251 172.16.11.1 100
>>
>>
>> Int fa0/1
>>  ip address 172.16.11.1 255.255.255.0
>>  ip multicast helper-map broadcast 224.0.0.251 100
>>
>> access-list 100 permit udp any any eq 5053
>>
>> Could you confirm my understanding of ip multicast helper-map ? or
>> point me where I am wrong ?
>>
>> On fa0/0, R1 will convert the multicast received on 224.0.0.251 and
>> forward it to fa0/1 as broadcast.
>> On fa0/1, R1 will reconvert it as multicast and forward the packet to
>> the other segment.
>>
>> thanks !
>>
>> Johan
>> _______________________________________________
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>
>
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