From: Andy (and123and@googlemail.com)
Date: Thu Feb 28 2008 - 14:19:39 ARST
aha, but, as there is no IP address on either main serial interface of R1 or
R6, then neither is going to :
a) send inverse-arp as there is no IP address to inverse-arp for, and
b) reply to inverse-arp as there is no one sending a request on this DLCI
pair
So, by putting the "no fr inv arp" command on we are not actually acheiving
anything that was not there before, the question said "ensure that DLCIs 110
and 104 between R1 and R6 are not used", I can not see what is gained by
adding the command. :-/
On 28/02/2008, Marc La Porte <marc.a.laporte@gmail.com> wrote:
>
> Yes, so as there are multiple DLCIs available on the main interface, and
> only one of those is used on the p2p sub-interface (which by default doesn't
> do I-ARP), it would make sense to use the "no frame inv" on the main
> interface to ensure no dynamic mapping between R1 and R6 is created via
> Inverse-ARP. You could also do this by moving all the non-used DLCIs to an
> unused multipoint sub-interface...
>
> Indeed, the Virtual-Interface as such has no influence on the InverseARP
> process.
>
> HTH.
> Marc
>
> On Thu, Feb 28, 2008 at 4:43 PM, Andy <and123and@googlemail.com> wrote:
>
> > For those that have the book, the question and diag are on p77. Lab 2.
> >
> > For those that dont: Hub and spoke with R4 as the hub.
> >
> > R1 has DLCI 101 and 110
> > R4 has DLCI 100 and 102
> > R6 has DLCI 104 and 103
> >
> > Mappings are
> > 101 - 100
> > 110 - 104
> > 103 - 102
> >
> > I hope you can follow this, the question is:
> >
> > - Config the FR portion of the network as shown in figure x and ensure
> > that DLCIs 110 and 104 between R1 and R6 are not used.
> > - Use p2p subinterfaces
> >
> > The solution shows IP address on p2p and "no fram inverse-arp" on the
> > main interface.
> >
> > The eventual solution uses PPP on the p2p interfaces with a virtual
> > interface but I mention it here only as reference, I do not think it matters
> > as to why we are using "no fr inv-arp" on main interface.
> >
> >
> >
> >
> >
> >
> >
> > R1 (ser0/1 DLCI 101) to R4 (ser0/0 DLCI 100)
> > R1 (ser0/1 DLCI 110) to R6 (ser5/0 DLCI 104)
> > R6 (ser5/0 DLCI 103) to R4 (ser0/0 DLCI
> >
> >
> > On 28/02/2008, Marc La Porte <marc.a.laporte@gmail.com> wrote:
> > >
> > > Andy,
> > >
> > > Are both DLCIs 104 and 110 on both R1 and R6? And the p2p
> > > sub-interface is for instance using DLCI 104 on both sides? Then the "no
> > > frame inv" makes sense on the main interface, because all DLCIs coming in
> > > from the FR switch on that main interface are automatically assigned to the
> > > main interface, so if you're using DLCI 104 (for instance) on your p2p
> > > sub-interface that still leaves you with DLCI 110 "assigned" to the main
> > > interface. Granted, as long as there is no IP address on the main interface
> > > there is no I-ARP going on (I listen to the Brian's too --- or should I say
> > > "the Brains"), but if you want to be sure then that's the way to go...
> > >
> > > If you could gives us a copy of the config that would help to (like
> > > you said) something subtle...
> > >
> > > Marc
> > >
> > > On Thu, Feb 28, 2008 at 3:43 PM, Andy <and123and@googlemail.com>
> > > wrote:
> > >
> > > > Hi
> > > >
> > > > On pages 92 and 93 of CCIE Routing and Switching LAB Practice labs
> > > > by Cisco
> > > > it gives a solution which uses "no frame relay inverse-arp" after
> > > > asking the
> > > > question "ensure that DLCIs 110 and 104 between R1 and R6 are not
> > > > used. The "no fr inverse-arp" is configed on a main interface and a
> > > > sub-interface used for p2p connection (with the IP going on the
> > > > sub-interface).
> > > >
> > > > Now I know that "no frame relay inverse-arp" on an interface without
> > > > an IP
> > > > address does nothing (coz I have read the mails from Brian Dennis
> > > > ;-) But
> > > > then why does the Cisco Press book award one point for this??? In a
> > > > lab
> > > > scenario I would not config the command where an IP address does not
> > > > exist
> > > > as I would view this as overconfiguration. Am I missing something
> > > > subtle
> > > > here?
> > > >
> > > > -A
> > > >
> > > >
> > > > _______________________________________________________________________
> > > > Subscription information may be found at:
> > > > http://www.groupstudy.com/list/CCIELab.html
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