multicast routing over network borders

Unanswered Question
Jul 19th, 2007


I'm searching for some hints on configuring multicast routing. Especially to get applications like apple's iChat (MDNS / running over ip network borders. I have a catalyst 3560 with c3560-ipservices-mz.122-25.SED1.bin which should act as (multicast) router.

I have tried configuraions like:

ip multicast-routing distributed


interface Vlan1

ip address

ip pim [dense-mode | sparse-mode | sparse-dense-mode]


interface Vlan2

ip address

ip pim [dense-mode | sparse-mode | sparse-dense-mode]


[ip pim rp-address]


but without any success.

Could someone of you be so kind and give me a hint or point me in the right direction.

thanks in advance and kind regards


I have this problem too.
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purohit_810 Sun, 07/22/2007 - 09:35

Try by following two commands

ip pim accept-rp {address | auto-rp} [group-access-list-number]

ip pim message-interval seconds


Dharmesh Purohit

d-mark Mon, 07/23/2007 - 23:39

Thanks for your response. I tried the command

ip pim accept-rp {address | auto-rp} [group-access-list-number]

but without success. The onther command you mentioned isn't supported in the IOS version I use.

But I think I know now why mDNS ( packets are not forewarded. At

it is said that multicast datagrams with addresses within to should not be forwarded by multicast routers.


Mark Sat, 02/05/2011 - 12:37

I know its a very very long time since this thread was started.

I just sah the following on IANA.ORG.

Last Updated

    Host Extensions for IP Multicasting [RFC1112] specifies the extensions
    required of a host implementation of the Internet Protocol (IP) to
    support multicasting.  The multicast addresses are in the range through Address assignments are listed below.

    The range of addresses between and, inclusive,
    is reserved for the use of routing protocols and other low-level
    topology discovery or maintenance protocols, such as gateway discovery
    and group membership reporting.  Multicast routers should not forward
    any multicast datagram with destination addresses in this range,
    regardless of its TTL.



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