RE: ip directed broadcast with ACL

From: Antonio Soares (amsoares@netcabo.pt)
Date: Thu Jul 05 2007 - 11:44:18 ART


I was able to test this with RTR. IP SLA infortunately does not support
dest-ipaddress=255.255.255.255.

R1-e1/0=====e1/0-R2-e1/1=====e0/1-R3

R1 is a broadcast source.

The objective is to forward this traffic to R3.

In R2's e1/0 we will need either:

1) ip helper-address 23.23.23.3, where 23.23.23.3 is R3's address

Or

2) ip helper-address 23.23.23.255

Then we must enable forwarding for this traffic, for example:

Ip forward-protocol udp 12345

If we use Unicast helper-address, we are good to go.

If we use the directed-broadcast address, we need in R2 e1/1 interface:

Ip directed-broadcast

If we want to restrict which traffic should be forwarded we may configure in
R2:

Access-list 102 permit udp any any eq 12345

Interface Ethernet1/1
 ip directed-broadcast 102

I may add some outputs if someone is interested.

-----Original Message-----
From: Mike Kraus (mikraus) [mailto:mikraus@cisco.com]
Sent: quinta-feira, 5 de Julho de 2007 14:55
To: Antonio Soares; darth router; ccielab@groupstudy.com
Subject: RE: ip directed broadcast with ACL

I've done scenarios in conjunction with an IP multicast helper map to
convert a RIPv1 broadcast into a 224.0.0.9 multicast for a remote segment.
The difference is there, on an ip multicast helper you can remap the ttl
value.

As Antonio pointed out, I only needed to configure the ip forward-protocol
on the router that is initiating the forwarding of broadcasts (R2 from R1
below).

However, in that scenario since I actually sent it over PIM, rather than a
directed broadcast, so I haven't ever labbed up the second part of the below
scenario. But, if you wanted to be crazy, I suppose you could then convert
the multicast (with the remapped ttl value) back into a broadcast and then
try to do it as a directed broadcast. I'm not eager enough to try to lab
this one up though. :)

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Antonio Soares
Sent: Thursday, July 05, 2007 7:12 AM
To: 'darth router'; ccielab@groupstudy.com
Subject: RE: ip directed broadcast with ACL

I would configure both:

1)In order be able to forward this traffic

ip forward-protocol udp mobile-ip

2) In order to actually forward the traffic

ip directed-broadcast 101
access-list 101 permit udp any any eq mobile-udp

The question is where should we configure this ?

R1====R2====R3

Imagine R1 as the Broadcast source. So we would need to configure 1) in
R2 and 2) in R2's interface facing R3.

Unfortunately i don't see an easy way to test this. Tried NTP Broadcast and
RIPv1 but they both have TTL=1.

Wait, maybe IP SLA... I will try it now.

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
darth router
Sent: quinta-feira, 5 de Julho de 2007 6:59
To: ccielab@groupstudy.com
Subject: Re: ip directed broadcast with ACL

If I were to forward mobile ip with the ip helper.

I could do both of these correct. This is doing the exact same thing,
right?

ip forward-protocol udp mobile-ip

OR Do:

 ip directed broadcast 101
permit udp any any eq mobile-ip

It does not look like using the ACL, and permitting mobile IP only, disables
the forwarding of the ip-helper default protocols. This right?

DR

On 7/5/07, darth router <darklordrouter@gmail.com> wrote:
>
> When you use this command with an ACL, does it disable the default
> forwarded protocols from the ip helper-address? Thanks,
>
> DR



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