Subject: BGP - IGP Redistribution Issue

From: "Abarbanel, Benjamin" <[email-masked]>
Date: Tue, 24 Sep 2002 11:15:09 -0400

> -----Original Message-----
> From: Jeffrey Haas [mailto:[email-masked]]
> Sent: Tuesday, September 24, 2002 11:09 AM
> To: Abarbanel, Benjamin
> Cc: [email-masked]
> Subject: Re: Generial Editorial Comment
> 
> 
> On Tue, Sep 24, 2002 at 10:27:48AM -0400, Abarbanel, Benjamin wrote:
> > While we are on the subject of BGP interworking with other 
> protocols. If its
> > a bad idea to redistribute the massive BGP tables into IGP 
> protocols such as
> > OSPF/ISIS, should we not have a rule in some spec 
> forbidding it from being
> > done
> > to avoid an IGP meltdown?
> 
> While some may disagree, it is not our place to take the loaded
> shotgun out of the hands of foolish network operators.  Not even
> if they point it at themselves, repeatedly press the trigger
> and wonder why people are telling them it is a bad idea.
> 
> Otherwise known as:
> Rope. Gallows. Have fun.
> 

Would it make sense to add the recommendation to RFC1772bis, in some
practical deployment techniques. I realize its hard to undue what has been
cast in concrete, but at least a recommendation could be added.

Ben

---

From: Jeffrey Haas <[email-masked]>
Date: Tue, 24 Sep 2002 11:28:34 -0400

Ben,

> cast in concrete, but at least a recommendation could be added.

As much as I would really like to incorporate some of the best current
practices that network operators have in operating BGP networks in
a 1772 replacement, we shouldn't try to reproduce works such as
Halabi's book in a RFC.

While redistributing your BGP into your IGP is a common mistake
(and usually one that you learn from very quickly) for many network
operators, there are valid situations where you may want to do
this intentionally.  The real trick is to make sure that the
redistributed routes are not accidentally re-injected back into
BGP to prevent re-origination.

One technique that I've heard of is to simply tag the injected routes
such that at the routers where IGP routes are injected that the
tagged routes are excluded.  But this is just one way, and there
is more than one way to...

Perhaps some suggestions from those who were about when 1772 was
written to figure out what we should be thinking about for it.

-- 
Jeff Haas 
NextHop Technologies