From: Anthony Bonilla (anthonybonilla.ccie@gmail.com)
Date: Fri Feb 23 2007 - 04:36:12 ART
Mike,
Thanks for looking into this and explaining it with a reference - I started
reading doc cd again after I got the reply from Dave and my understanding is
the same as you outlined below. Thanks again for everyone's help. I really
appreciate it!
Tony
On 2/23/07, Michael Zuo <mzuo@ixiacom.com> wrote:
>
> From the DocCD:
>
> "
> The ip directed-broadcast 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.
>
> If directed broadcast is enabled for an interface, incoming IP packets
> whose addresses identify them as directed broadcasts intended for the
> subnet to which that interface is attached will be exploded as
> broadcasts on that subnet. If an access list has been configured with
> the ip directed-broadcast command, only directed broadcasts that are
> permitted by the access list in question will be forwarded; all other
> directed broadcasts destined for the interface subnet will be dropped.
> "
>
> IMO, the command need to be configured on the receiving end...
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Anthony Bonilla
> Sent: Thursday, February 22, 2007 9:21 PM
> To: Schulz, Dave
> Cc: ccielab@groupstudy.com
> Subject: Re: Helper address and directed broadcast Question
>
> Okay, I think I got it - thanks a lot for your help.
>
> On 2/22/07, Schulz, Dave <DSchulz@dpsciences.com> wrote:
> >
> > No, the helper addresses will allow you to direct broadcasts for say,
> > DHCP. Pixie, etc for startup. The directed broadcast would relate to
> > allowing directed broadcast out od the interface. Afaik, as it was
> > explained to me.. Hope this helps.
> >
> > Dave Schulz
> > *** Sent from my Blackberry ***
> >
> > -----Original Message-----
> > From: Anthony Bonilla <anthonybonilla.ccie@gmail.com>
> > To: Schulz, Dave
> > CC: ccielab@groupstudy.com <ccielab@groupstudy.com>
> > Sent: Wed Feb 21 22:40:32 2007
> > Subject: Re: Helper address and directed broadcast Question
> >
> > Dave,
> >
> > Thanks for your response - I was beginning to think that my messages
> were
> > not making it to the GS but now I feel a lot better after you replied.
> >
> > In any event, just to make sure that I got it: if you look at my
> depiction
> > of the setup, if we were asked to enable HSRP on the LAN interface of
> Router
> > R1 and use LAN broadcast address between Routers R3 and R4. In that
> case,
> > are you saying that I should enable helper address on the LAN
> interfaces of
> > both R1 and R4 and don't need to enable directed broadcast on either
> of the
> > interfaces (I thought that I had to have directed-broadcast enabled on
> R4's
> > LAN interface and would only enable helper address on R1's LAN
> interface so
> > that the traffic is directed towards the LAN segment between R and
> R4)? Pls
> > elaborate a bit, if at all possible. Thanks again for taking the time
> to
> > respond.
> >
> > Tony
> >
> >
> > On 2/21/07, Schulz, Dave <DSchulz@dpsciences.com> wrote:
> >
> > Anthony -
> >
> > You will want to enable the ip helper on both routers that are
> > acting as
> > the hsrp group. The ip helper will provide the directed
> > broadcast.
> > HTH.
> >
> >
> > Dave Schulz,
> > Email: dschulz@dpsciences.com
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> <mailto:nobody@groupstudy.com<nobody@groupstudy.com>>
> > [mailto:nobody@groupstudy.com <nobody@groupstudy.com>] On Behalf Of
> > Anthony Bonilla
> > Sent: Wednesday, February 21, 2007 9:12 PM
> > To: ccielab@groupstudy.com
> <mailto:ccielab@groupstudy.com<ccielab@groupstudy.com>
> > >
> > Subject: Re: Helper address and directed broadcast Question
> >
> > Any takers? Can someone pls answer the following question
> because
> > I
> > have
> > tried searching archives but hasn't been able to find a
> definitive
> > answer as
> > yet? Would appreciate someone's help with this.
> >
> > Thx.
> >
> >
> > On 2/19/07, Anthony Bonilla <anthonybonilla.ccie@gmail.com>
> wrote:
> > >
> > > Hello GS,
> > >
> > > First of all, I would like to apologize for asking this
> basic
> > (for
> > some on
> > > this group) question but I have this doubt in my mind for
> some
> > time
> > now and
> > > wanted to see if someone from this group can help me
> understand
> > this
> > > concept. If we enable HSRP on a router for users connected
> to
> > one of
> > it's
> > > LAN interfaces (LAN interface of router R1 in the below
> > presentation)
> > and
> > > then use broadcast address of another router's LAN segment
> (say,
> > LAN
> > > interface between R3 and R4) as the address for IP HELPER
> > ADDRESS
> > command,
> > > where would I need to worry about enabling directed
> broadcast?
> > >
> > > LAN --- R1 --- Serial --- R2 --- Serial --- R3 ---- LAN ----
> R4
> > >
> > > Also, if someone would be kind enough to let me know if I
> need
> > to
> > enable
> > > broadcast support at all if the helper address is, let's
> say,
> > R4's
> > > LAN interface address?
> > >
> > > I look forward to your response to this question.
> > >
> > > TIA,
> > >
> > > Tony.
> >
> >
> >
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