From: shiran guez (shiranp3@gmail.com)
Date: Sat Oct 13 2007 - 10:08:17 ART
it was not my question, I just answered it.
On 10/13/07, Gary Duncanson <gary.duncanson@googlemail.com> wrote:
>
> Hi Shiran
>
> Obviously there is some problem of interpretation of your specific
> question going on here! What exactly are you asking for confirmation of?
>
> '.The question here is if the link between r1 and r4 is broken and r1
> >> > > recieves an ebgp updates from outside..will it fwd it to R4??'
>
> From my interpretation of that question, I reckon that R4 will receive
> R1's ebgp update providing the peering between R1 and R4 is still up.
>
>
>
>
> ----- Original Message -----
> *From:* shiran guez <shiranp3@gmail.com>
> *To:* Gary Duncanson <gary.duncanson@googlemail.com>
> *Cc:* ccielab@groupstudy.com ; Joseph Saad <joseph.samir.saad@gmail.com>
> *Sent:* Saturday, October 13, 2007 1:42 PM
> *Subject:* Re: bgp peering+RR
>
>
> yes and that is the case here! if you look into the first note there was
> no special indication regarding what is going on in the IGP, so if all
> routers advertise there local interfaces and IGP is working properly then
> unless R4 lost all its interfaces to the IGP he will be still peering with
> R1 and R3
>
> On 10/13/07, Gary Duncanson <gary.duncanson@googlemail.com> wrote:
> >
> > Shiran,
> >
> > The peering between R1 and R4 will stay up even if the link between R1
> > and R4 is down providing there is reachability to R4's loopback via another
> > path i.e R3 and R4.
> >
> > In this event R4 should still receive the eBGP learned route from R1.
> >
> > ----- Original Message -----
> > *From:* shiran guez <shiranp3@gmail.com>
> > *To:* Gary Duncanson <gary.duncanson@googlemail.com>
> > *Cc:* Joseph Saad <joseph.samir.saad@gmail.com> ; ccielab@groupstudy.com
> > *Sent:* Saturday, October 13, 2007 12:43 PM
> > *Subject:* Re: bgp peering+RR
> >
> >
> > If I didn't test it myself then I would drought my self now,
> >
> > But I did test it my self and even tough R4 is loosing the physical
> > connection to R1 it is still peering with him as they are peering via
> > loopback
> >
> > I have set EIGRP as the IGP and Advertised in each router all the
> > interface
> >
> > R1 R3 and R4 are peering via lo0 so even if the direct interface is down
> > peering between R1 to R4 is down only in case that R4 or R1 are down
> > completely as long as the IGP is ok.
> >
> > In normal scenario with no any out of the ordinary manipulation as long
> > as the IGP is ok unless R4 is down in all interface it will never loose
> > peering.
> >
> >
> > On 10/13/07, Gary Duncanson <gary.duncanson@googlemail.com > wrote:
> > >
> > > I have to agree with Joseph so far. The R1 - R4 reachability seems to
> > > be the
> > > clincher in the argument. Assuming iBGP peering between R1 and R4
> > > remains up
> > > due to IGP I would expect R4 (AS 100) to have the ebgp update received
> > > by
> > > R1(AS 100). If down it looks like the route reflector rules in this
> > > scenario
> > > won't save the situation and R4 gets no iBGP route.
> > >
> > > Or perhaps I'm missing something?
> > >
> > > Gary
> > > ----- Original Message -----
> > > From: "Joseph Saad" < joseph.samir.saad@gmail.com>
> > > To: "shiran guez" < shiranp3@gmail.com>; "Cisco certification"
> > > <ccielab@groupstudy.com>
> > > Sent: Saturday, October 13, 2007 9:49 AM
> > > Subject: Re: bgp peering+RR
> > >
> > >
> > > > R1
> > > > / \
> > > > / \
> > > > r3-----r4
> > > > / \ / \
> > > > / \ / \
> > > > r2 r5 r2
> > > >
> > > > I still disagree, R4 couldn't be possibly learning the route from
> > > R2.
> > > >
> > > > The statement of "if R2 is learning it, it will pass to the entire
> > > domain
> > > > including R1" is flawed because R2 is not a ROUTE-REFLECTOR. It's
> > > merely a
> > > > CLIENT to both R3 and R4 as per the original post .... "I am
> > > planning to
> > > > make r2 and r5 as rr-clients for r3 and r4" ...
> > > >
> > > > so iBGP learnt route on R2 reflected from R3 can't be possibly be
> > > > reflected
> > > > to other neighbors as this breaks the full mesh rule and R2 is not a
> > >
> > > > route-reflector.
> > > >
> > > > Let's review the assumptions: R3, R4 are Route reflectors. Both of
> > > R2 and
> > > > R5
> > > > are each a route-reflector of client of both R3 and R4.
> > > >
> > > > We may need a 3rd opinion on the topic.
> > > >
> > > > I am afraid that one of us is missing something, but I don't know
> > > who.
> > > >
> > > > Cheers,
> > > > Joseph.
> > > >
> > > > On 10/12/07, shiran guez < shiranp3@gmail.com > wrote:
> > > >>
> > > >> Please notice to the initial note both R3 and R4 are RR Server for
> > > R2 and
> > > >> R5!
> > > >> and for that meter both R3 and R4 learned the same from R1 and they
> > >
> > > >> reflect to R2 and R5.
> > > >> also if R2 is learning it will pass to the entire domain including
> > > R1.
> > > >>
> > > >>
> > > >>
> > > >> On 10/11/07, Joseph Saad < joseph.samir.saad@gmail.com > wrote:
> > > >> >
> > > >> > whether R1 and R4 Loopbacks still reachable by R4 and R1
> > > respectively.
> > > >> > Independent of Route reflection, if reachability is maintained
> > > via
> > > >> > other
> > > >> >
> > > >> > means (e.g. via R3) the R1 eBGP-learnt routes will be advertised
> > > to R4
> > > >> > via
> > > >> > the direct iBGP peering between R1 and R4. in Summary, the iBGP
> > > peering
> > > >> > is
> > > >> > not broken in the first place.
> > > >> >
> > > >> > If not, then you need to consider the Route-reflection rules.
> > > >> >
> > > >> > Jeff Dolye Page 137: RFC 1966 defines three rules that the RR
> > > uses to
> > > >> > determine who the route is advertised to, depending on how the
> > > route
> > > >> > was
> > > >> > learned:
> > > >> > l If the route was learned from a non-client IBGP peer, it is
> > > reflected
> > > >> > to
> > > >> > clients only.
> > > >> > l If the route was learned from a client, it is reflected to all
> > > >> > nonclients
> > > >> > and clients, except for the originating client.
> > > >> > l If the route was learned from an EBGP peer, it is reflected to
> > > all
> > > >> > clients
> > > >> > and nonclients.
> > > >> >
> > > >> > with R3 as the route-reflector, it has learnt the route via a
> > > >> > non-client
> > > >> > iBGP peer (from R1), hence it will be reflected to clients only
> > > (R2 &
> > > >> > R5).
> > > >> > Which means R4 shouldn't receive it.
> > > >> >
> > > >> > Hope this helps.
> > > >> >
> > > >> > Joseph.
> > > >> >
> > > >> > On 10/10/07, slevin kremera < slevin.kremera@gmail.com> wrote:
> > > >> > >
> > > >> > > R1
> > > >> > > / \
> > > >> > > / \
> > > >> > > r3-----r4
> > > >> > > / \ / \
> > > >> > > / \ / \
> > > >> > > r2 r5 r2
> > > >> > >
> > > >> > >
> > > >> > > here all the routers are in as100. r1-r3-r4 are full meshed
> > > and
> > > >> > peering
> > > >> > > wit
> > > >> > > lo0. r2 and r5 are peering with r3 and r4..I am planning to
> > > make r2
> > > >> > and r5
> > > >> > >
> > > >> > > as rr-clients for r3 and r4
> > > >> > >
> > > >> > > .The question here is if the link between r1 and r4 is broken
> > > and r1
> > > >> > > recieves an ebgp updates from outside..will it fwd it to R4??
> > > >> > >
> > > >> > >
> > > >> >
> > > _______________________________________________________________________
> > > >> > > Subscription information may be found at:
> > > >> > > http://www.groupstudy.com/list/CCIELab.html
> > > >> >
> > > >> >
> > > _______________________________________________________________________
> > > >> > Subscription information may be found at:
> > > >> > http://www.groupstudy.com/list/CCIELab.html
> > > >> >
> > > >>
> > > >>
> > > >>
> > > >> --
> > > >> Shiran Guez
> > > >> MCSE CCNP NCE1
> > > >> http://cciep3.blogspot.com
> > > >> http://www.linkedin.com/in/cciep3
> > > >
> > > >
> > > _______________________________________________________________________
> > > > Subscription information may be found at:
> > > > http://www.groupstudy.com/list/CCIELab.html
> > >
> > >
> >
> >
> > --
> > Shiran Guez
> > MCSE CCNP NCE1
> > http://cciep3.blogspot.com
> > http://www.linkedin.com/in/cciep3
> >
> >
>
>
> --
> Shiran Guez
> MCSE CCNP NCE1
> http://cciep3.blogspot.com
> http://www.linkedin.com/in/cciep3
>
>
-- Shiran Guez MCSE CCNP NCE1 http://cciep3.blogspot.com http://www.linkedin.com/in/cciep3
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