From: Eric Phillips (eric@phillips.tc)
Date: Mon Jan 12 2009 - 19:00:52 ARST
Hi CCIE To Be,
In your case if AS 30 consists of only R3, then both options will give the
exact same result. However, if AS 30 has multiple routers, then you need to
carefully read the question. If it says not to export the prefix to any AS
beyond 30, then "no-export" is the right choice; all routers within AS 30
will have that route, but no ASes beyond that will. If the wording of the
question implies that no router except for R3 should know of that prefix,
then no-advertise would be preferred.
On a related note, make sure to put "send-community" on the end of the
neighbor statement; many people forget that Cisco routers do not send
communities to any peers by default.
Hope that helps!
-Eric Phillips
-- Eric M. Phillips Senior Network ConsultantLTI Information Technology http://www.ltiit.com 501 Avis Drive Ann Arbor, MI 48108
Phone: (734) 929-1400 Fax: (734) 929-1401
On Mon, Jan 12, 2009 at 2:28 PM, CCIE To Be <ccie.tobe81@gmail.com> wrote:
> Dear Group, > > I have a confusion regarding usage of no-advertise and no-export > communities. I know that no-advertise means NOT TO ADVERTISE to any bgp > peer > ( iBGP & eBGP ) whereas no-export says NOT TO ADVERTISE to any eBGP peer > means don't advertise outside this AS. Consider the following topology, > > R1(AS 10) --------R2(AS 10)------------R3(AS 30) > > Let say AS 10 is advertising a prefix to AS 30 and requirement is that AS > 30 > should not forward this prefix further to any other AS. Now we have option > to use either no-advertise or no-export on R2 towards R3. Both will give > the > desired result , what should be the recommended approach here ?? > > > HTH > > > Blogs and organic groups at http://www.ccie.net > > _______________________________________________________________________ > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net
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