From: NET HE (he_net@hotmail.com)
Date: Sun Feb 22 2009 - 18:47:35 ARST
Jason,
Firstly, I'd like to say thank you for your correcting my understanding.
And I labbed it up, to sum it up
-OSPF
Under ospf process, distribute-list out is not allowed "OUT direction is not
allowed in the case of OSPF"
-EIGRP
Under EIGRP process, distribute-list out followed by routing process such as
RIP, static, connected etc, is used to prevent specific routes sourced by the
defined routing process from advertising out in EIGRP process
-RIP
the same as eigrp
Best Regards,
Net (Xin) He
Date: Sun, 22 Feb 2009 12:16:02 -0700
Subject: Re: Recursive Routing and Tunnels
From: madsen.jason@gmail.com
To: he_net@hotmail.com
CC: all.from.nj@gmail.com; mcnever@gmail.com; ccielab@groupstudy.com
well...yes and no. keep in mind "distribute-list out" in OSPF only works for
external routes (E1 or E2). it can be used to prevent the passing of OSPF
external routes into another routing protocol / AS, but it can also be used to
prevent externally learned routes from going into OSPF. I know, if we want to
prevent routes from going "into" OSPF than why not just use distribute-list
in? Well, it's just another way to do it. As we all know if there are 5
ways to do a task, it's highly possible that the CCIE lab will tell us we
can't use 4 of the ways.
if OSPF is learning of the 3.3.3.0/24 route from EIGRP, than you can use
"distribute-list 1 out" in your OSPF process on your ASBR to prevent it from
entering your OSPF domain. you can use options like " distribute-list 1 out
eigrp 100" to specify not only the routes, but which protocol they should be
coming / learned from also. You can't specify an interface however like you
can with distribute-list in.
Jason
#23420
On Sun, Feb 22, 2009 at 9:28 AM, NET HE <he_net@hotmail.com> wrote:
I think the command "distribute-list out" Jason referred to is used to control
routes being redistributed into other routing process. For example,
redistributing OSPF routes into RIP, you can use either redistribution
route-map under RIP process to control routes redistributed into RIP or
distribute-list route-map out RIP under OSPF process to control routes
redistributed into RIP.
Best Regards,
Net (Xin) He
> Date: Sat, 21 Feb 2009 22:05:22 -0700
> Subject: Re: Recursive Routing and Tunnels
> From: madsen.jason@gmail.com
> To: all.from.nj@gmail.com
> CC: mcnever@gmail.com; ccielab@groupstudy.com
>
> no, the command is distribute list out...not data-base filter. you can do
> it on ASBRs for external routes. try it out.
>
> Jason
>
> On Sat, Feb 21, 2009 at 10:03 PM, ALL From_NJ <all.from.nj@gmail.com>
wrote:
>
> > Yeah ... I seem to remember something about this distribute list rule ...
> > Thanks for mentioning this.
> >
> > The command:
> > ip ospf database-filter all out
> >
> > This command filters the LSA outgoing, but ... it is not a distribute
> > list.
> >
> >
> >
> >
> > On Sun, Feb 22, 2009 at 12:00 AM, Jason Madsen
<madsen.jason@gmail.com>wrote:
> >
> >> you can do them outbound if you're an ASBR.
> >>
> >> Jason
> >>
> >> On Sat, Feb 21, 2009 at 9:56 PM, Jason Morris <mcnever@gmail.com>wrote:
> >>
> >>> something to keep in mind about how ospf distribute lists work
> >>>
> >>> you can never do a distribute list OUT with OSPF.
> >>>
> >>> OSPF filters LSAs from the ospf database to the routing table vs
> >>> filtering
> >>> routes advertised or recieced from a neightbor like eigrp or rip does.
> >>>
> >>> all the databases in an area have to have the same info or ospf can't
> >>> calculate paths correctly.
> >>>
> >>> if that makes since.
> >>>
> >>> jason
> >>>
> >>>
> >>>
> >>> On Sat, Feb 21, 2009 at 11:35 PM, ALL From_NJ <all.from.nj@gmail.com>
> >>> wrote:
> >>>
> >>> > Interesting lab testing tonight, was playing w/ tunnel interfaces and
> >>> OSPF.
> >>> >
> >>> >
> >>> > I had a scenario I was practicing, basically it was:
> >>> >
> >>> > NBMA w/ network type of non-broadcast. Can not use neighbor command
or
> >>> > make
> >>> > any config changes to the physical interface on either sides.
> >>> >
> >>> > So I created a tunnel and added it to OSPF.
> >>> >
> >>> > As you would expect, recursive routing began to occur.
> >>> >
> >>> > Here is a nifty debug output which quickly showed why the neighbor
> >>> bounces:
> >>> >
> >>> > R2#debu ip ospf adj
> >>> > OSPF adjacency events debugging is on
> >>> >
> >>> > *Mar 1 04:34:36.531: %TUN-5-RECURDOWN: Tunnel1 temporarily disabled
> >>> due to
> >>> > recursive routing
> >>> > *Mar 1 04:34:37.531: %LINEPROTO-5-UPDOWN: Line protocol on Interface
> >>> > Tunnel1, changed state to down
> >>> > *Mar 1 04:34:37.531: OSPF: Interface Tunnel1 going Down
> >>> >
> >>> > I know one answer to solve this is to simply remove the physical
link's
> >>> > network address from OSPF. Odd learning though, as I tried to
> >>> configure
> >>> > other method of filters.
> >>> >
> >>> > OSPF would not take a distribute list OUT for the tunnel interface
...
> >>> > figured I would simply keep the local physical link's network from
> >>> being
> >>> > advertised out via the tunnel. No-go on this.
> >>> >
> >>> > OSPF did take a Distribute list IN via the tunnel. I denied the local
> >>> > link's network ... and all was well in la-la land (where I live).
> >>> >
> >>> > R1(config-router)#distribute-list 12 in tunnel 1
> >>> >
> >>> > Would have been easier and quicker for me to simply remove the
physical
> >>> > link's network from OSPF, but I was / am learning ...
> >>> >
> >>> > Also, ... I actually prefer a distribute list IN, since if I am able
to
> >>> > keep
> >>> > the physical link's network in OSPF on my hub router, other peers
will
> >>> > still
> >>> > learn about it. I am only filtering via these two routers, and all
> >>> other
> >>> > routers still learn about the local link's network.
> >>> >
> >>> > Question for the group:
> >>> >
> >>> > For recursive learning, any additional thoughts on ways for me to
learn
> >>> > this
> >>> > / explore this / solve this?
> >>> >
> >>> > I suppose in all of life, the kiss method is the best ... Just
figured
> >>> I
> >>> > would ping yall to see what insights I might learn.
> >>> >
> >>> > Many TIA,
> >>> >
> >>> > Andrew Lee Lissitz
> >>> >
> >>> > --
> >>> > Andrew Lee Lissitz
> >>> > all.from.nj@gmail.com
> >>> >
> >>> >
> >>> > Blogs and organic groups at http://www.ccie.net
> >>> >
> >>> >
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