From: Vijay Venkatesh (vijay.venkatesh@xxxxxxx)
Date: Sun Aug 13 2000 - 23:45:49 GMT-3
I don't know but a concept like a default-net in BGP if available and
if someone configureed it could potentially bring down the internet.
Imagine if my edge router was default for everything on the internet -
man that will be a tangy recipe for diaster. NO !! no defautl-net for
BGP !! BGP must know where it is coming and where it is going exactly.
No default-nonsense. With EIGRP or IGRP you only mess up your corp
network not the entire internets' so it is somewhat safe.
Vijay.
"Mark H. Degner" wrote:
>
> Eugene,
>
> You bring up some good points, but default routes in BGP can actually be quit
e useful. For
> instance, if a corporation were to use a 4000 series router as its Internet r
outer running BGP, it
> would not support the memory required for the full Internet BGP tables. In t
his case, the customer
> would usually request the ISPs customer routes, and a default route. Due to
the proximity of most
> upper tier ISPs to regional NAPs, this is often a better solution than runnin
g full routes.
> Assuming, of course, the customer is more interested in advertising their pre
sence than being aware
> of every route on the Internet. Often, full BGP routes do not optimize route
s enough to make them
> worthwhile. This all depends on the implementation, or course. So in cases
like this, partial
> routes from the ISP suffice. If you connect to two ISPs, it is good to get t
heir customer routes,
> so traffic that would normally never leave their network doesn't traverse the
other ISPs link.
> Default routes on both links then give you the link redundancy you would want
. I guess what I'm
> trying to say is, default routes in BGP have their merits, when implemented i
n the appropriate
> situations.
>
> I hope this makes sense..
>
> Sincerely,
>
> Mark Degner
>
> CCIE #6110 (as of today)
>
> ----- Original Message -----
> From: "Eugene Nesterenko" <eenest@msn.com>
> To: "Harbir Kohli" <harbirk@sympatico.ca>; "'Ccielab" <ccielab@groupstudy.com
>
> Sent: Sunday, August 13, 2000 7:27 PM
> Subject: RE: BGP default network
>
> > Harbir,
> >
> >
> > That's the different story.
> >
> > IGRP and EIGRP are effectively IGP-class protocols.
> > On the contrary - BGP in most cases runs defaultless - i.e the BGP-speaking
> > boxes have no defauls - they know where-and-how-to-get-there.
> >
> > In the typical scenario, BGP is used on the edge of the local/corporate
> > network - i.e. at
> > the point where it connects to the real world - i.e. Internet.
> >
> > IN that case trying to inject any kind of default in BGP, and more, to
> > EXPORT that knowledge
> > can create real disaster in Internet. Of course that's the bad idea.
> >
> > Can you imagine that your leaf network will say to the whole world that it'
s
> > DEFAULT ROUTE
> > FOR ALL AND EVERYTHING IN THIS WOLD, ESPECIALLY FOR ALL THAT HAVE NO
> > EXPLICIT
> > ROUTES (or just wrong)?
> >
> > In that case - using anything like "I'm default" in BGP-world has no sence
> > at all.
> >
> > But in IGP-world - that's normal.
> > You have small network - you have one (or may be 2) outbound connections to
> > the "BIG WORLD"
> > In that case you can instruct your IGP-protocol - it can be OSPF, EIGRP,
> > RIP - what you actually like -
> > to say "here's default route - send all the stuff that you have-no-idea
> > where-to-send to this default path"
> >
> > And it'll work.
> >
> > Of course in that case you can get some problem with the "sync-no-sync"
> > dilemma (with your BGP).
> > But that's another question.
> >
> >
> > Regards,
> >
> > Eugene
> >
> > -----------------------------------------
> > Eugene Nesterenko, CCIE #5283, CCNP+Security, CCDP, MCSE
> > Fax/Voicemail: +1 415 7043497
>
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