From: Eugene Nesterenko (eenest@xxxxxxx)
Date: Sun Aug 13 2000 - 23:14:10 GMT-3
Sure, you're right
But again - we live in the real world.
In that case I'm sure that the main idea is to understand the placement and
limitations
of the protocols/technology/etc....
In case of your scenario - the guys who use 4000 box, even in a multihoming
environment
are really strange. The monthly/quarterly payment for the links will be
almost the same as the price for
the new - better - router/memory (depends on the speed of the links and the
model).
So in that case more and more guys going defaultless.
Also - using any kind of defaults in the dual-homing environment can be
really tricky.
That's my personal point of view.
Of course I fully admit all that you noticed is true but acording to my
personal experience:
1. people either don't need BGP at all - they just sit as the leaf node -
mostly if they have less then /19 prefix.
2. people use confederations - to get some redundancy from the same ISP (the
same problem - less then /19 prefix)
3. people run full (defaultless) BGP - they have /19 or more and they can
afford to be defaultless.
4. people have /19 or more but they are LAZY or have STRANGE management -
using some kind of your scenario
So that's the story.
Never seen other scenarios working out of the lab - i.e. in the real world.
Of course - since BGP is the policy routing tool, you can make really lot of
tricks with the prefered paths and so on...
Of course your mileage may vary :-)
Regards,
Eugene
PS. In priciple you can run Windows NT on a 386 computer - sure it'll work.
But I'm not sure that you'll like that...
-----------------------------------------
Eugene Nesterenko, CCIE #5283, CCNP+Security, CCDP, MCSE
Fax/Voicemail: +1 415 7043497
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Mark
H. Degner
Sent: Monday, August 14, 2000 6:05 AM
To: ccielab@groupstudy.com
Subject: Re: BGP default network
Eugene,
You bring up some good points, but default routes in BGP can actually be
quite useful. For
instance, if a corporation were to use a 4000 series router as its Internet
router running BGP, it
would not support the memory required for the full Internet BGP tables. In
this 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
running full routes.
Assuming, of course, the customer is more interested in advertising their
presence than being aware
of every route on the Internet. Often, full BGP routes do not optimize
routes 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
their 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
in 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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