From: Richard Dumoulin (richard.dumoulin@vanco.es)
Date: Fri Mar 05 2004 - 21:56:47 GMT-3
To me it seems that what you want is bridging. Just configure bridge-group 1
on all interfaces and delete the ip addresses,
--Richard
-----Mensaje original-----
De: Kenneth Wygand [mailto:KWygand@customonline.com]
Enviado el: sC!bado, 06 de marzo de 2004 1:47
Para: Scott, Tyson C; ccielab@groupstudy.com
Asunto: RE: Forwarding UDP Broadcasts (not all-1's)
Scott,
Thanks for the update. I probably should've been a bit clearer:
Say I have the following topology
[192.1.1.0/24] (E0--R1--S0) ===T1 link=== (S0--R2--E0) [192.2.2.0/24]
Say I have a workstation with address 192.1.1.100 with an application that
broadcasts UDP packets to locate services on the local subnet. Say the UDP
packet is destination port 1234 and is a directed network broadcast but for
the LOCAL NETWORK (192.1.1.255/24). I want this UDP network broadcast to
reach a workstation on the 192.2.2.0/24 subnet (say 192.2.2.100). So
essentially I want R1 to take that network broadcast and forward it to every
attached router (in this case, R2 - possibly by converting it to an all-1's
broadcast). Then I want R2 to forward it to all attached routers and all
local LAN interfaces, so it spills onto the 192.2.2.0/24 network so the
workstation sitting at 192.2.2.100 receives the broadcast.
Maybe I need to enable DLSW or something, but I have so many LAN segments
that it would be a much cleaner solution if I could do something like IP
FORWARD-PROTOCOL UDP 1234.
Any thoughts? Maybe I just need to run "IP directed-broadcast" on E0
because I think it is currently turned off for security purposes.
Any suggestions are welcome. Thanks in advance,
Ken
-----Original Message-----
From: Scott, Tyson C [mailto:tyson.scott@hp.com]
Sent: Fri 3/5/2004 7:35 PM
To: Kenneth Wygand
Cc:
Subject: RE: Forwarding UDP Broadcasts (not all-1's)
Thank you
-----Original Message-----
From: Chen Kwong Wai William [mailto:kwchen05@hotmail.com]
Sent: Friday, March 05, 2004 12:38 PM
To: Scott, Tyson C
Subject: Re: ip multicast helper-map - ip directed broadcast
Hi Scott,
The command "ip directed-broadcast" in DocCD is: "To enable the
translation of a directed broadcast to physical broadcasts" amd also
it
states:
=======
A router that is not directly connected to its destination subnet
forwards an IP directed broadcast in the same way it would forward
unicast IP packets destined to a host on that subnet. When a
directed
broadcast packet reaches a router that is directly connected to its
destination subnet, that packet is "exploded" as a broadcast on the
destination subnet. The destination address in the IP header of the
packet is rewritten to the configured IP broadcast address for the
subnet, and the packet is sent as a link-layer broadcast. The ip
directed-broadcast interface command controls the explosion of
directed
broadcasts when they reach their target subnets. The command affects
only the final transmission of the directed broadcast on its
ultimate
destination subnet. It does not affect the transit unicast routing
of IP
directed broadcasts.
======
Therefore, the directed-broadcast command only should be enabled
on
the interface connected to the destination subnet. For example,
192.168.1.1 -E0- (RouterA) -E1- 192.168.2.1
Then E0 will be the inbound and E1 as the final destination of
the
directed-broadcast 192.168.2.255.
Now, if RouterA receives a packet to 192.168.2.255 on E0, RouterA
will forward it to 192.168.2.1 no matter whether "ip
directed-broadcast"
is enable on this interface or not. However, when the packet reaches
E1,
then RouterA will drop the packet if E1 has "no ip
directed-broadcast",
but will explode as a physical broadcast (255.255.255.255) if E1
has
"directed-broadcast".
Therefore, I believe that "directed-broadcast" is only need to be
enable on the interface where the broadcast will be finally sent to
(i.e. the outbound interface).
Best Regards,
William Chen.
----- Original Message -----
From: "Scott, Tyson C" <tyson.scott@hp.com>
To: "William Chen" <kwchen05@hotmail.com>; <braet_kamiel@nl.ibm.com>
Sent: Friday, March 05, 2004 8:36 PM
Subject: RE: ip multicast helper-map - ip directed broadcast
You are correct my broadcast statement is incorrect. It should be
10.3.3.255 PIM is not required on the Ethernet segments since it is
being re-encapsulated into broadcast at the end and it starts as a
broadcast. But you are going to be running PIM across the WAN and
not on
the Ethernet? What client is going to join a multicast group on the
WAN?
Here is why I believe you need ip directed-broadcast on both the
Ethernet interfaces. When a broadcast is received on an interface
it is
automatically dropped by the router it does not forward it on when
it is
inbound or outbound without this statement. The router would drop
the
broadcast before it ever goes through the process of mapping the
multicast from the broadcast. At least this is how I understood it
when
it was explained to me. I have not tested it with a packet
generated to
verify what has been told to me. It does make logical sense to me
from
my understanding of how other processes work in the IOS but who ever
said that the code writers for IOS are always logical.
-----Original Message-----
From: William Chen [mailto:kwchen05@hotmail.com]
Sent: Thursday, March 04, 2004 11:09 PM
To: Scott, Tyson C; braet_kamiel@nl.ibm.com
Subject: Re: ip multicast helper-map - ip directed broadcast
Dear scott,
Just find maybe you make some typo in your example, see below:
Best Regards,
William Chen
> Here is an example of how to do it. You have a broadcast you want
> forwarded to another subnet from R1 ethernet0 to R2 Ethernet0 and
the
> port of the broadcast is going to be 5959. I think it makes
better
> sense seeing a good example than the wrong example that is shown
on
the
> doc CD.
>
> e0-R1-s0->s0-R2-e0
>
> R1#
> ip multicast-routing
> ip forward protocol udp 5959
> !
> Interface Ethernet0
> Ip address 10.1.1.1 255.255.255.0
> Ip pim dense-mode
> - enable multicast routing on the interface
> Ip multicast helper-map broadcast 239.39.39.39 115
> - map the broadcast to a multicast
> Ip directed-broadcast
Maybe, you should not to enable directed-broadcast here, because
you
don't do any multicast to broadcast in the incoming interface (S0 of
R1).
> - accept the broadcast defined
> !
> interface Serial0
> ip address 10.2.2.1 255.255.255.0
> ip pim dense-mode
> !
> access-list 115 permit any any eq 5959
> - define which port you are going to accept as a directed
broadcast !
> end
>
> R2#
> ip multicast-routing
> ip forward protocol udp 5959
> !
> Interface Ethernet0
> Ip address 10.3.3.3 255.255.255.0
> Ip pim dense-mode
> - enable multicast routing on the interface
Why to enable multicast here?
> Ip directed-broadcast
> - accept the broadcast defined
> !
> interface Serial0
> ip address 10.2.2.2 255.255.255.0
> Ip multicast helper-map 239.39.39.39 10.2.2.255 115
The broadcast address should be 10.3.3.255, coz you are sending
directed broadcast to E0.
> - map the multicast to a broadcast
> ip pim dense-mode
> !
> access-list 115 permit any any eq 5959
> !
> end
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
Kenneth Wygand
Sent: Friday, March 05, 2004 7:28 PM
To: ccielab@groupstudy.com
Subject: Forwarding UDP Broadcasts (not all-1's)
Hi everyone,
If I want to forward (flood) all UDP broadcasts to all subnets
attached
to a router, how can this be accomplished? The application
initiating
the UDP broadcast is sending out a network broadcast, not an all-1's
broadcast. So if the application resides on a workstation with a
10.0.0.1 address, the UDP broadcast is 10.255.255.255, not
255.255.255.255. I want the broadcast to reach all other networks
attached to the router, say for example, 11.0.0.0, 12.0.0.0 and
such.
As far as I understand, "IP FORWARD-PROTOCOL UDP xxx" will only
forward
all 1's broadcasts and will not convert the network broadcast to an
all-1's broadcast. Is this correct?
For some reason I'm wondering if a "multicast helper map" can be
contorted to help accomplish my goal.
Please let me know your opinions, and thank you in advance!
Ken
This archive was generated by hypermail 2.1.4 : Thu Apr 01 2004 - 08:15:15 GMT-3