if you only had a connection to 1 as at one site, no reason to use bgp at
all, just static default it.
Redistributing bgp into an igp is generally not a good thing to do, it'll
hammer an underequipped router..
Suppose u work for a company with connections to 2 isps. Further suppose
that in order to not fall victim to hardware failure, you use different
routers for each connection. How is 1 router supposed to know what routes
the other peering session is receiveing?? IBGP is how that happens.
You'd typically run IBGP between the 2 routers, so that you'd have the
best of both available.
Brian "Sonic" Whalen
Success = Preparation + Opportunity
On Wed, 8 Aug 2001, Ole Drews Jensen wrote:
> Thanks Peter.
>
> I have browsed through Howards's BGP series, but for me, sometimes too long
> explanations are more frustrating than a 10 words fact.
>
> Two additional questions if you don't mind, and you have a minute or two
:-)
>
> 1)
>
> If you only have one BGP connection to one remote AS, IBGP would normally
> never be used, and you would in most cases create a static default route to
> the BGP router and redistribute it in your IGP. Am I right?
>
> 2)
>
> Should you have multiple BGP routers in the AS connected to two different
> remote AS's - would I always configure IBGP between them, or would there be
> situations where IBGP would still be unused?
>
> Thanks again,
>
> Ole
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ole Drews Jensen
> Systems Network Manager
> CCNA, MCSE, MCP+I
> RWR Enterprises, Inc.
> [EMAIL PROTECTED]
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> http://www.RouterChief.com
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> NEED A JOB ???
> http://www.oledrews.com/job
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> -----Original Message-----
> From: Peter Van Oene [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, August 08, 2001 2:38 PM
> To: Ole Drews Jensen; [EMAIL PROTECTED]
> Subject: Re: BGP: IBGP usage/clarification [7:15333]
>
>
> A couple quick notes. However I would suggest if you have a subscription
> that you step through Howards BGP series at www.certificationzone.com as it
> might help you solidify your understanding.
>
> First off, IBGP is not an IGP. If you want to get from point A to point B
> in AS C, IBGP isn't your friend (unless operator X tweaked IBGP with lots
of
> messiness -ie NHS everywhere etc....) IBGP facilitates inter-AS routing by
> enabling reachability information to be maintained within AS's. IGP are
> still required to enable routing within the AS (ie intra-AS routing).
>
> IBGP is used when you have multiple BGP routers in an AS. Really not much
> more to it than that at a high level. Whether or not you chose to use a
> dynamic IGP versus a static configuration really is up to the administrator
> with typical pros/cons applying. I have seen some cases where stub AS's
> (those not providing transit) may have border routers communicating via BGP
> to ISP's without peering amongst themselves but these are pretty unique
> (weird) situations which often beg the question why BGP in the first place,
> but this would be an fruitless digression.
>
> Pete
>
>
> *********** REPLY SEPARATOR ***********
>
> On 8/8/2001 at 3:06 PM Ole Drews Jensen wrote:
>
> >This might sound like a stupid question, but I have now read and
> >practised a
> >lot of BGP stuff, but there's one thing I am not 100% sure I understand;
> >None of the books have been able to put the last brick in place in the
> >puzzle for me.
> >
> >In what situations will "end-user" companies use IBGP and not just an IGP
> >as
> >OSPF or EIGRP?
> >
> >I believe that most ISP's use IBGP with a full mess where there are more
> >than one EBGP connection - right?
> >
> >And a question to those of you who do a lot of BGP setup's for customers,
> >how often do you typically use BGP at "end-user" companies and how often
> >will IBGP be used there with or without an IGR running on their
network(s)?
> >
> >Thanks for any comments on this,
> >
> >Ole
> >
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Ole Drews Jensen
> > Systems Network Manager
> > CCNA, MCSE, MCP+I
> > RWR Enterprises, Inc.
> > [EMAIL PROTECTED]
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > http://www.RouterChief.com
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > NEED A JOB ???
> > http://www.oledrews.com/job
> >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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