From: Andy (trung@vnsystem.net)
Date: Fri Jul 29 2005 - 23:29:11 GMT-3
Tim,
Let take a look a little bit closer on the diagram (i'll redraw it now)
e0--R1--s0------s0--R2--e0
mtc---------brc---------mtc
Ok, now let me try step by step with my understanding.
First of all, i'll try to convert mcast to bcast:
R1(e0):
!
ip multicast helper-map 224.1.1.1 172.16.255.3 100
ip pim dense-mode
ip forward-protocol udp 2000
access-list 100 permit any any udp 2000
At this point, because routers do NOT forward broadcast traffic (as you
said), so i put ip directed-broadcast on S0:
R1(s0)
!
ip directed-broadcasts
!
Now, at the far end (R2), i'll convert the bcast back to mcast.
So right on s0 of R2:
!
ip multicast helper-map broadcast 224.1.1.1 100
!
and last on e0 of R2:
R2(e0)
!
ip forward-protocol udp 2000
access-list 100 permit any any udp 2000
!
Well, you see, i don't have to put more "ip directed-broadcast" in there,
R2's interface e0, because i do a bcast-->mcast translattion, not the
opposite direction.
if it was incorrect, pls drop a comment.
Thanks
Lee.
----- Original Message -----
From: "ccie2be" <ccie2be@nyc.rr.com>
To: "'Brian Lee'" <ipgirl@gmail.com>; "'Andy'" <trung@vnsystem.net>; "'k c'"
<jwongccie@yahoo.com.hk>; "'Cisco certification'" <ccielab@groupstudy.com>
Sent: Saturday, July 30, 2005 12:40 AM
Subject: RE: Re Re: <PCD!G Re: IP Multicast helper
Lee,
Maybe it would help to remember the basics:
By default, routers do NOT forward broadcast traffic.
Therefore, on the last hop router, after it converts the mcast to bcast,
unless you have ip directed-broadcast configured on the lan interface,
bcasts won't be forwarded out that interface (or any other interfaces for
that matter).
If you want to test this, try this:
R1 ---- R2 -------- R3 ------ R4
bcast mcast bcast
On R2 and R3 configure mcast helper to convert the bcast to mcast and back.
Then do a debug on R4 with the appropriate acl configured and see what
happens.
HTH, Tim
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian Lee
Sent: Friday, July 29, 2005 1:11 PM
To: Andy; ccie2be; 'k c'; 'Cisco certification'
Subject: Re Re: <PCD!G Re: IP Multicast helper
Tim,
I don't think at the far end, converting broadcast to multicast would need
the ip directed-broadcast enabled.
Lee.
> ----- Original Message -----
> From: "ccie2be" <ccie2be@nyc.rr.com>
> To: "'k c'" <jwongccie@yahoo.com.hk>; "'Andy'" <trung@vnsystem.net>;
> "'Cisco
> certification'" <ccielab@groupstudy.com>
> Sent: Friday, July 15, 2005 10:01 PM
> Subject: RE: <PCD!G Re: IP Multicast helper
>
>
>> Andy,
>>
>> I'm pretty sure the config you have for R2 is missing a critical command.
>>
>> By default, broadcasts aren't ever forwarded by routers. Therefore, for
>> R2
>> to forward broadcasts onto E0, you need to add the ip directed-broadcast
>> command. Without this command, R2 after converting the mcast to
>> broadcast
>> traffic will just drop it.
>>
>> This is difficult to test without some sort of packet capture device
>> hanging
>> off of R2's E0 interface but I'm 99% sure I'm correct.
>>
>> HTH, Tim
>>
>> -----Original Message-----
>> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of k
>> c
>> Sent: Friday, July 15, 2005 8:12 AM
>> To: Andy; Cisco certification
>> Subject: <PCD!G Re: IP Multicast helper
>>
>> Hi Andy,
>>
>> I have 2 questions:
>> 1) Does the config work in Sparse mode?
>> 2) Do I need to type "join-group 224.1.1.1" anywhere?
>>
>> Thanks,
>>
>> Andy <trung@vnsystem.net> ;!!G
>> Hi,
>> Hope this could help
>>
>> e0--R1--s0------s0--R2--e0
>>
>> R1
>>
>> Interface Ethernet0
>> ip address 10.1.1.1 255.255.255.0
>> ip multicast helper-map 224.1.1.1 172.16.255.3 100
>> ip pim dense-mode
>> ip forward-protocol udp 2000
>> access-list 100 permit any any udp 2000
>>
>> interface S0
>> ip address 172.16.255.1 255.255.255.252
>> ip directed-broadcasts
>>
>> R2
>>
>> Interface Serial0
>> ip address 172.16.255.2 255.255.255.252
>> ip multicast helper-map broadcast 224.1.1.1 100 ttl 15
>>
>>
>> interface Ethernet0
>> ip address 10.2.2.1 255.255.255.0
>> ip pim dense-mode
>> ip forward-protocol udp 2000
>> access-list 100 permit any any udp 2000
>>
>>
>> Andy
>>
>> ----- Original Message -----
>> From: "k c"
>> To:
>> Sent: Thursday, July 14, 2005 10:34 PM
>> Subject: IP Multicast helper
>>
>>
>>> Hi Group,
>>>
>>> In Config Guide, the example given is to convert broadcast -->
>>> Multicast --> broadcast. Is it possible to convert Multicast -->
>>> Broadcast --> Multicast? If not, suppose I have routers with the
>>> following
>>> connection:
>>> M.Src -- R1-- R2 -- R3 -- Receiver
>>> If R2 cannot run multicast and assuming not allow to build a GRE tunnel
>>> between R1 and R3. How can the multicast traffic reach R3 send from R1.
>>>
>>> Thanks,
>>>
>>>
>>> 8g;if8,h)&d;6e01/d;%3ie<5g
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>
>>
>> %og+
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
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