From: Joseph Brunner (joe@affirmedsystems.com)
Date: Thu Nov 08 2007 - 15:56:59 ART
If not specifically asked in a real-world requirement (forget the lab) to
fine tune my acl it would be
Access-list 115 permit udp any any eq 5556 , etc
This for stock ticker machines that like to be routed via multicast.
On a lab, the task may give you a hint to how they want it
i.e. "ONLY PERMIT broadcasts sent to the lan subnet broadcast address to be
converted", etc.
I doubt any real multicast traffic will be coming in from the bb's etc you
will have do "debug ip packet 116 detail" where
Access-list 116 permit udp any any to find out, but who knows how they could
bring this question to you. Be prepared to understand how the helper-map
works, what it looks for, how it forwards, everything.
-----Original Message-----
From: Rich Collins [mailto:nilsi2002@gmail.com]
Sent: Thursday, November 08, 2007 1:48 PM
To: William Nellis
Cc: Joseph Brunner; Anthony Sequeira; Cisco certification
Subject: Re: Errors in the DOC-CD for Multicast Intermediate Helper
So how does it work on the ingress router in this case? For example
the application is sending udp broadcasts (port 2323) to int Fa 1/0
ip address 172.16.10.1 255.255.255.0
Should the access list to detect this be
Extended IP access list UDP_BROADCAST
permit udp any host 172.16.20.255 eq 2323
OR in case they are 255.255.255.255 ?
permit udp any host 255.255.255.255 eq 2323
Would it be wrong to configure the ip broadcast-address in both or
either case (ingress or egress)?
-Rich
On Nov 8, 2007 11:58 AM, William Nellis <nellis_iv@yahoo.com> wrote:
> food for thought, the client isn't listening to IP per se, the client will
pick up from the wire anything sent to ffff.ffff.ffff, L2 broadcast address.
>
> I am quite certain you do not need to explicitly configure broadcast
address on the interface... its automagically configured as a result of the
IP/subnet mask combination...
>
> IE, if you don't explicitly configure it, it uses the deafult, which is
the all 1's in the host portion of the subnet... Oh yes, the router knows
it's broadcast address... the router knows all... mua ha ha ha
> ip broadcast-address
> To define a broadcast address for an interface, use the ip
broadcast-address interface configuration command. To restore the default IP
broadcast address, use the no form of this command.
> ip broadcast-address [ip-address]
> no ip broadcast-address [ip-address]
> Syntax Description
> ip-address (Optional) IP broadcast address for a network.
>
>
> -------------------------------------------------------
> r/s
> William Nellis IV
> nellis_iv@yahoo.com
>
>
>
> ----- Original Message ----
> From: Joseph Brunner <joe@affirmedsystems.com>
> To: Rich Collins <nilsi2002@gmail.com>; Anthony Sequeira
<Anthony_Sequeira@skillsoft.com>
> Cc: Cisco certification <ccielab@groupstudy.com>
> Sent: Thursday, November 8, 2007 8:46:18 AM
> Subject: RE: Errors in the DOC-CD for Multicast Intermediate Helper
>
> No the client will listen to 255.255.255.255 also, it's a local broadcast.
>
> That is just a caveat- the router realizes it's a directed broadcast, but
> Sends by default to 255.255.255.255 instead of 126.1.28.255
>
> -Joe
>
> -----Original Message-----
> From: Rich Collins [mailto:nilsi2002@gmail.com]
> Sent: Thursday, November 08, 2007 10:19 AM
> To: Anthony Sequeira
> Cc: Joseph Brunner; Cisco certification
> Subject: Re: Errors in the DOC-CD for Multicast Intermediate Helper
>
> This has always confused me as well.
>
> So on the final egress router in your example you would have this:
>
> int S0/0
> ip pim sparse-dense
> ip multicast helper-map 239.254.2.5 126.1.28.255 105
>
> int Fa0/0
> ip add 126.128.1 255.255.255.0
> ip directed-broadcast
> ip broadcast-address 126.1.28.255
>
>
> This is the best configuration to have the client of the application
> pick up the UDP broadcast stream? I suppose this is better than the
> default 255.255.255.255 broadcast which the client might not listen
> to?
>
> -Rich
>
>
>
>
> On Nov 8, 2007 7:42 AM, Anthony Sequeira <Anthony_Sequeira@skillsoft.com>
> wrote:
> > Yeah - thanks Joe!
> >
> > This example used to be way off and had us placing commands on the wrong
> > interfaces I believe.
> >
> > Anthony J. Sequeira
> > #15626
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >
> > Joseph Brunner
> > Sent: Wednesday, November 07, 2007 9:58 PM
> > To: Anthony Sequeira; 'Cisco certification'
> > Subject: RE: Errors in the DOC-CD for Multicast Intermediate Helper
> >
> > You mean the new documentation way in-line with current IOS where we
> > place
> >
> > This
> >
> >
> > ip multicast helper-map 239.254.2.5 126.1.28.255 105
> >
> >
> > on the interface facing the multicast , not sending the final "back to
> > lan
> > broadcast" ?
> >
> > One cool thing-
> >
> > By default IOS sends "directed broadcasts" to 255.255.255.255 (even if
> > the
> > command above specified "126.1.28.255" as the broadcast to address). If
> > you
> > *really* want to send the broadcast to the subnet broadcast (directed)
> > address you need to put ip broadcast-address 126.1.28.255 on the out
> > going
> > interface...
> >
> > Lab it up sometime, check it out...
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Anthony Sequeira
> > Sent: Wednesday, November 07, 2007 9:19 PM
> > To: Cisco certification
> > Subject: Errors in the DOC-CD for Multicast Intermediate Helper
> >
> > Hello all!
> >
> >
> >
> > I am too tired right now to investigate so I am looking for immediate
> > assistance from the group...it would appear that Cisco has finally
> > corrected the Multicast Helper example in the DOC-CD.
> >
> >
> >
> > Can someone please confirm....
> >
> > http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cg/hi
> > mc_c/chap10/mcbcigmp.htm#wp1084257
> >
> >
> >
> >
> >
> > Thanks in advance!
> >
> >
> >
> > Anthony J. Sequeira
> >
> > #15626
> >
> > _______________________________________________________________________
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This archive was generated by hypermail 2.1.4 : Sat Dec 01 2007 - 06:37:29 ART