From: Peng Zheng (zpnist@yahoo.com)
Date: Thu Jan 16 2003 - 22:19:53 GMT-3
Is only a default route enough? When synchronization
is enabled, I think for each route to be inserted into
routing table, a same route should be learned from
IGP. Now only a default route is learned, I think if
a IBGP peer learns a default route, it will put it
into routing table. How about other routes?
Thanks for help.
--- Robert Miller <rmiller@absitech.com> wrote:
> Follow the rules:
>
> 1. (pg 123) In order for IBGP to work, Peers must be
> fully meshed or routes must be redistributed into
> and syncronized with IGP.
>
> 2. If IBGP peers are fully meshed, syncronization
> must be disabled in order to inject routes learned
> from EBGP into the routing table as it traverses the
> IBGP group.
>
> On pg 245, we know that sycronization was not
> disabled, so IBGP could NOT inject the routes into
> the routing table from the BGP table.
>
> Based on LOCAL_PREF settings, both Zermatt and
> Moritz know from the BGP table which path they will
> take to the respective AS.
>
> Now for the fun part!
>
> 1. We know that BGP did not inject the routes into
> the routing table because syncronization was not
> disabled.
>
> 2. We know that BGP is not redistibuted into IS-IS,
> so this did not inject the routes into the routing
> table.
>
> 3. But, Because default routes were created and
> injected into the routing table, the IBGP peers are
> able to get to their preferred paths.
>
> Hope this helps....
>
> Robert
>
> ------------------------------------------------
> On Thu, 16 Jan 2003 07:53:03 -0800 (PST), Peng Zheng
> <zpnist@yahoo.com> wrote:
>
> > I just took a look, but I didn't see the reason.
> It
> > only mentioned it is different with the earlier
> > examples. I don't know why synchronization is not
> > disabled.
> >
> >
> >
> > --- Robert Miller <rmiller@absitech.com> wrote:
> > > Peng,
> > >
> > > Look at page 245. It explains why the use of
> the
> > > default route bypasses the affect caused by the
> IGP
> > > (IS-IS) and synchronization.
> > >
> > > Later...
> > >
> > > Robert
> > >
> > >
> > > ------------------------------------------------
> > > On Thu, 16 Jan 2003 02:24:14 -0500, "cebuano"
> > > <cebu2ccie@cox.net> wrote:
> > >
> > > > Peng,
> > > > I haven't mocked up this lab yet, but based on
> the
> > > configuration,
> > > > Zermatt and Moritz are learning about AS50, 75
> and
> > > 100 via their eBGP
> > > > peers as well so BGP synchronization should
> have
> > > not effect on these
> > > > routers' path selection. I'll let you know
> after
> > > I've mocked this up.
> > > >
> > > > Gotta sign off now.
> > > > Elmer
> > > >
> > > > -----Original Message-----
> > > > From: Peng Zheng [mailto:zpnist@yahoo.com]
> > > > Sent: Thursday, January 16, 2003 2:07 AM
> > > > To: cebuano; ccielab@groupstudy.com
> > > > Subject: RE: BGP synchronization
> > > >
> > > > I know the path is prefered. But because
> > > > synchronization are not disabled on Zermatt
> and
> > > > Moritz, the route learned only from IBGP
> should
> > > not be
> > > > put in routing table if it is not learned by
> IGP.
> > > >
> > > > Right?
> > > >
> > > >
> > > >
> > > > --- cebuano <cebu2ccie@cox.net> wrote:
> > > > > Peng,
> > > > > Check the LOCAL_PREF values for both iBGP
> > > routers.
> > > > >
> > > > > -----Original Message-----
> > > > > From: nobody@groupstudy.com
> > > > > [mailto:nobody@groupstudy.com] On Behalf Of
> > > > > Peng Zheng
> > > > > Sent: Wednesday, January 15, 2003 11:56 PM
> > > > > To: ccielab@groupstudy.com
> > > > > Subject: BGP synchronization
> > > > >
> > > > > Hi,
> > > > >
> > > > > On page 242-244 of Routing TCPIP V2, why
> Zermatt
> > > use
> > > > > Moritz to 172.18.0.0?
> > > > >
> > > > > I think it's not synchronized because it's
> not
> > > > > learned
> > > > > by IGP.
> > > > >
> > > > > Any idea?
> > > > >
> > > > > Thanks for help.
> > > > >
> > > > > Best Wishes,
> > > > > Peng Zheng
> > > > >
> > > > >
> > >
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> > > > > .
> > > > >
> > > >
> > >
> >
>
This archive was generated by hypermail 2.1.4 : Sat Feb 01 2003 - 07:33:51 GMT-3