From: Anthony Sequeira (terry.francona@gmail.com)
Date: Thu Nov 24 2005 - 10:42:19 GMT-3
Hi Leigh!
Errr - take another look - R1 and R4 are running iBGP with each other -
setting NEXT-HOP-SELF on the peering from R1 to R4 will have no effect.
Since R4 must use R2 to reach R1 - traffic will still be black-holed at R2.
On 11/24/05, Leigh Harrison <ccileigh@gmail.com> wrote:
>
> Hey there Anthony,
>
> If you don't want to redistribute bgp into igp (not that popluar with
> me!), then you could pop in "next-hop-self".
>
> This way the next hop for the destinations can be found via the igp. No
> redistributing required. :)
>
> LH
>
> Anthony Sequeira wrote:
>
> >Hi *Venkataramanaiah.R!*
> >You are correct in that we do not need a tunnel for the iBGP peering to
> work
> >between R1 and R4 through R2. As you know - the iBGP peerings do not need
> to
> >be direct connections. The issue will come later with reachability. For
> >example - if we advertise a prefix into BGP on R1 - R4 will not have
> >reachability due to a "black-hole" situation on R2.
> >
> >I do not want to redistribute BGP into the IGP here - so I wanted to play
> >with the tunnel option as I describe here.
> >
> >
> >
> >On 11/24/05, Venkataramanaiah.R <vramanaiah@gmail.com> wrote:
> >
> >
> >>I do not understand the need for tunnel interfaces here for the IBGP
> >>to work via R2. Am i missing something here?
> >>
> >>-Venkat
> >>
> >>On 11/24/05, Tim <ccie2be@nyc.rr.com> wrote:
> >>
> >>
> >>>A couple things I noticed:
> >>>
> >>>1) The tunnel endpoints should be on R1 and R4, not R2.
> >>>
> >>>2) You didn't adjust the cost of the tunnel to make it less preferred
> >>>
> >>>
> >>path
> >>
> >>
> >>>than the physical path.
> >>>
> >>>3) I would use the physical interface as the tunnel source on each
> >>>
> >>>
> >>router.
> >>
> >>
> >>>4) If using the lo0 for the tunnel ip address doesn't work, you can
> try
> >>>using the ip address of the physical interface for the tunnel address.
> >>>
> >>>Just a couple ideas,
> >>>
> >>>Tim
> >>>
> >>>-----Original Message-----
> >>>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >>>Anthony Sequeira
> >>>Sent: Wednesday, November 23, 2005 9:42 PM
> >>>To: Cisco certification
> >>>Subject: Let's Tunnel BGP Due to Non-BGP Speaker in Transit Path!
> >>>
> >>>I want to tunnel my iBGP peering from R1 to R4 because R2 is not
> running
> >>>BGP. I want to use the loopback 0 interfaces for the peerings. The IGP
> >>>
> >>>
> >>in
> >>
> >>
> >>>use is EIGRP and all of the interfaces shown below are running EIGRP.
> >>>
> >>>
> >>>
> >>>R1-----4.4.8.0/24-----R2-----4.4.12.0/24-----R4
> >>>
> >>>
> >>>
> >>>R1 lo0 4.4.1.1/24
> >>>
> >>>R4 lo0 4.4.4.4/24
> >>>
> >>>
> >>>
> >>>I have this sample scenario labbed up and I am having a heck of a time.
> >>>
> >>>
> >>I
> >>
> >>
> >>>have tried the following with no luck:
> >>>
> >>>
> >>>
> >>>Attempt 1
> >>>
> >>>R1:
> >>>
> >>>int tunnel 0
> >>>
> >>>ip unnumbered lo0
> >>>
> >>>tunnel source 4.4.8.1
> >>>
> >>>tunnel destination 4.4.12.4
> >>>
> >>>
> >>>
> >>>R2:
> >>>
> >>>int tunnel 0
> >>>
> >>>ip unnumbered lo0
> >>>
> >>>tunnel source 4.4.12.4
> >>>
> >>>tunnel destination 4.4.8.1
> >>>
> >>>
> >>>
> >>>Attempt 2
> >>>
> >>>R1:
> >>>
> >>>int tunnel 0
> >>>
> >>>ip unnumbered lo0
> >>>
> >>>tunnel source lo0
> >>>
> >>>tunnel destination 4.4.4.4
> >>>
> >>>
> >>>
> >>>R2:
> >>>
> >>>int tunnel 0
> >>>
> >>>ip unnumbered lo0
> >>>
> >>>tunnel source lo0
> >>>
> >>>tunnel destination 4.4.1.1
> >>>
> >>>
> >>>
> >>>You see this is easy and works great if I create a new subnet for the
> >>>tunnel and use that in my BGP peerings the issue that I am having is
> >>>trying to use the loopback addresses for the peerings and still use my
> >>>tunnel.
> >>>
> >>>
> >>>
> >>>I notice that my tunnel interface does not show up in the routing table
> >>>
> >>>
> >>when
> >>
> >>
> >>>I am pulling the address from the loopback..I guess this must be why
> my
> >>>
> >>>
> >>BGP
> >>
> >>
> >>>is not using it????
> >>>
> >>>
> >>>
> >>>Anyone feel like labbing this one up and trying this one? Or is it
> >>>
> >>>
> >>something
> >>
> >>
> >>>really simple that I am missing about tunnels?
> >>>
> >>>
> >>>
> >>>Thanks in advance for you consideration of this e-mail.
> >>>
> >>>_______________________________________________________________________
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> >>>
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> >>>
> >>>
> >
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