[j-nsp] Conditional Advertisemet?

[Mellott, Eric]

Yeah, this is exactly the problem I am running into and didn't know if
there were any options available other than the generate route.  
  
Unfortunately, I don't have the JNCIP book handy, but will see if I can
find it.  

Thank you for the responses.

-Eric


-----Original Message-----
From: Dale Gregory [mailto:dalegreg at centurytel.net] 
Sent: Thursday, October 05, 2006 4:01 PM
To: Harry Reynolds; Chuck Anderson; Mellott, Eric
Cc: juniper-nsp at puck.nether.net
Subject: Re: [j-nsp] Conditional Advertisemet?

Harry, I am sure you remember this since you wrote the book, ;-) but 
your JNCIP book on pg 530 says, "newer versions of JUNOS software 
will not allow a more specific route to recurse through a less 
specific route because this behavior could lead to recursion loops."

Eric, on pgs 530-538 & 573-579 there are several listed options and 
explanations on how to deal with situations like this that may help you
out.

Dale


At 02:33 PM 10/5/2006, Harry Reynolds wrote:
>Hmm. Normally a generate/aggregate route is activated by a
more-specific
>route, i.e., contributing prefix.
>
>In this case you are trying to activate a more specific generated with
a
>less specific contributing route, which I do not think will work. The
>forwarding NH of a generated route is determined by the FNH of the
>preferred contributing route. Forwarding for a /28 over a /16 could
lead
>to loops.
>
>
>Regards
>
>
> > -----Original Message-----
> > From: juniper-nsp-bounces at puck.nether.net
> > [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of
> > Chuck Anderson
> > Sent: Thursday, October 05, 2006 12:19 PM
> > To: Mellott, Eric
> > Cc: juniper-nsp at puck.nether.net
> > Subject: Re: [j-nsp] Conditional Advertisemet?
> >
> > On Thu, Oct 05, 2006 at 01:59:17PM -0400, Mellott, Eric wrote:
> > > Have a BGP configuration where I learn a /16 network from one eBGP
> > > neighbor and want to advertise a subset of that network,
> > i.e. a /28,
> > > to a different eBGP neighbor.  Currently, I am able to
> > advertise the
> > > subnet by configuring a static route which puts the /28 in table,
> > > however; this kills anything dynamic.  Is there a way with
> > conditional
> > > advertisements or a generate route to dynamically advertise the
/28
> > > upon receipt of the /16?  Also, I don't want to rely on the BGP
> > > neighbor (who is advertising the /16) to give me the /28 instead.
> >
> > This might work:
> >
> > [edit routing-options]
> > # show generate
> > route w.x.y.z/28 policy MATCH-16;
> >
> >
> > [edit policy-options]
> > # show policy-statement MATCH-16
> > term 1 {
> >     from {
> >         route-filter w.x.0.0/16 exact;
> >     }
> >     then accept;
> > }
> > term 2 {
> >     then reject;
> > }
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> >
>
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