From: alain faure (alainfaure@xxxxxxxx)
Date: Thu Feb 14 2002 - 19:15:09 GMT-3
Hello,
A network is redistributed from a protocol to an other one, by the route table:
If the network is not in the route table no redistribution occur.
For example: if you have 3 routing protocols (A,B,C) on a router and 2 (A,B)
having the same network in they database, if protocol A redistribute to
protocol C but protocol B has is route in the table (by the way of the
administrative distance), no redistribute occur.
An other example: if you have a network in a protocol database and put a
"distribute-list ... in" to avoid the network to be in the routing table the
network will not be redistribute.
Best regard
--- steven.j.nelson@bt.com a icrit : > FYI
>
> If you redistribute information from one routing protocol to another all
> information is redistributed unless you filter with a route-map or something
> similar eg. This is why we have route-maps and other tools available.
>
> If you redistribute RIP into EIGRP then all routes learnt via RIP or that
> are covered by the network command under the RIP routing process will be
> redistributed into eigrp using the various metrics, connected networks that
> are not under any routing process will require the redist connected command
> to allow them to enter the routing process via redistribution.
>
> Ta
>
> Steve
>
> -----Original Message-----
> From: Lab Candidate [mailto:labccie@yahoo.com]
> Sent: 14 February 2002 19:51
> To: RPF; Xu, James; ccielab@groupstudy.com
> Subject: RE: How route redistribution EXACTLY works --- need
> confirmation
>
>
> Ross,
>
> Will rip redist into ospf any routes learnt from its neighbors
> but not covered by its own network commands?
>
> --- RPF <rpf@multilayer.co.uk> wrote:
> > My view, (and probably wrong)
> >
> > If you redistribute from RIP into another, then it will redistribute what
> > you have in your RT, providing it is covered by a RIP network command, so
> if
> > you have a connected route in your table that is not covered by the
> network
> > statement then it will not be redistributed, you will have to perform
> > redistribute connected ?
> >
> > any takers ?
> >
> > Ross.
> > -----Original Message-----
> > From: Xu, James [mailto:james.xu@eds.com]
> > Sent: 14 February 2002 19:28
> > To: 'RPF'; ccielab@groupstudy.com
> > Subject: RE: How route redistribution EXACTLY works --- need
> > confirmation
> >
> >
> > Ross:
> >
> > Trust me, you will not be able to answer this question by reading through
> > Doyle. I have been reading through it a couple of times.
> >
> > As far as your last comment, a CCIE may not be able to answer this
> question
> > clearly. If you think it is easy, give a try!
> >
> > Like what I said, I am puting myself in beating position. :-)
> >
> > James
> > -----Original Message-----
> > From: RPF [mailto:rpf@multilayer.co.uk]
> > Sent: Thursday, February 14, 2002 2:09 PM
> > To: Xu, James; ccielab@groupstudy.com
> > Subject: RE: How route redistribution EXACTLY works --- need
> > confirmation
> >
> >
> > James,
> >
> > In my opinion, it would probably be beneficial to read Doyle, Vol I from
> > Cisco press, as the amount of info you need to know I don't think can be
> > summarized in a few sentences.
> >
> > If you want CCIE, you need to read it anyhow. :-)
> >
> > Ross.
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Xu, James
> > Sent: 14 February 2002 18:44
> > To: 'Todd Carswell'; ccielab@groupstudy.com
> > Subject: RE: How route redistribution EXACTLY works --- need
> > confirmation
> >
> >
> > Todd:
> >
> > You are right, I am looking for answers about the "core mechanism" of the
> > redistribution process. The points you presented are well valid.
> >
> > Here I am puting up a stroke man to let everyone to punch on, hopefully on
> > the way, we all can get complete understanding. I, personally, didnot find
> > much public documentaion to explain this.
> >
> > Some points I am going after are :
> >
> > 1). does the routing process pick routes out of routing database or out of
> > routing table to do the redistribution? I am a believer of the former. But
> I
> > would like some input on this, documentation even better.
> > 2). does, in fact, the split-horizon rule applies here. It is my
> experience
> > let me believe so. Further confirmation needed.
> > 3). if possible if someone can post the algorithm related to the
> > redistribution.
> >
> > Just a little more for chewing.
> >
> > James
> >
> > -----Original Message-----
> > From: Todd Carswell [mailto:acarswell@nc.rr.com]
> > Sent: Thursday, February 14, 2002 1:04 PM
> > To: Xu, James; ccielab@groupstudy.com
> > Subject: Re: How route redistribution EXACTLY works --- need
> > confirmation
> >
> >
> > Your description of the process sounds correct to me. That description is
> a
> > "10,000 foot view" of redistribution.
> >
> > The tricky part of redistribution is two-fold:
> >
> > 1. You have to make sure that the metrics from one protocol are
> distributed
> > properly into another. (i.e. hop-count in RIP translated into the OSPF
> > metric.)
> >
> > 2. If you're redistributing from a classFUL protocol into a classLESS
> > protocol (RIP to OSPF), you have to deal with classful networks not being
> > visible in the classless domain.
> >
> > Somebody please beat me about the head and shoulders if I've got it wrong
> or
> > if I've omitted something. :-)
> >
> > Todd Carswell
> >
> >
> >
> >
> > ----- Original Message -----
> > From: "Xu, James" <james.xu@eds.com>
> > To: <ccielab@groupstudy.com>
> > Sent: Thursday, February 14, 2002 11:57 AM
> > Subject: How route redistribution EXACTLY works --- need confirmation
> >
> >
> > > All:
> > >
> > > It has been and still puzzling me how a routing process pick routes and
> > > redistribute them into another routing process and vice versa? As an
> > > example, mutual redistribution between RIP and OSPF in a router:
> > >
> > > Here is my experience and explanation:
> > >
> > > 1). The RIP process picks all RIP routes inside its database, and
> > > redistributes these routes into OSPF routing process.
> > > 2). OSPF process picks all OSPF routes in the OSPF database, and
> > > redistributes these routes into RIP routing process.
> > >
> > > During the redistribution, the split-horizon rule appies, meaning the
> > newly
> > > redistributed routes from RIP into OSPF will not be redistributed back
> > into
> > > RIP right away, and vice versa.
> > >
> > > Any input are appreciated, especially some links for this mechnism.
> > >
> > > James
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