In a way, you are both right. James is right for many cases of
multihomed transit AS (i.e., those without pervasive iBGP). Brian is
right for multihomed non-transit AS.
>On Fri, 18 Aug 2000, Hixon Sgt James R Jr wrote:
>
> > This is wrong Brian, and you need research some things before you
>tell other
> > people the wrong answers. You want to turn the BGP sync off by the no sync
> > command, so that the BGP routes will be in the IGP routing table. This is a
> > rule of BGP scalability issues, and you DO NOT want it off if you are
> > connecting to multiple ISP's or service providers. Again, the link to look
> > at this is
>
>
>James,
>
>Please, no anamosity needed.......I am honestly trying to give the right
>advice here.
>
>If you run BGP4, to multiple upstream providers, from your border router,
>you would, in most cases (95%) run with "no sync"........that is the most
>common thing to do. Just talking in general terms, if you have a router
>network, which has a border router, and all your transit comes into it,
>keeping it simple, you normally dont start distributing igp's into bgp and
>bgp into igp's etc, and you normally run with "no sync".
>
>The way it is usually handled, is you run BGP with "no sync". Make
>"network" entries in your BGP config for the aggregate networks you are
>announcing. Nail down your aggregate routes by creating static routes on
>your border to either a loopback or null interface with a high
>administrative distance (250).
>
>For most of the time, the transit routers all speak BGP, and so running no
>sync is the way to go. In cases where you are passing transit over
>multiple routers, and you are using iBGP, yadda yadda, then yes sync may
>have its place.
>
>If all your transit borders run BGP.......then you don't have a
>problem. They, and only they, really need to know about BGP routes, the
>rest of the network can just reach those routes via default.
>
>Brian
>
>
> >
> > http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/icsbgp4.htm
> >
> > -----Original Message-----
> > From: Brian [mailto:[EMAIL PROTECTED]]
> > Sent: Thursday, August 17, 2000 7:10 AM
> > To: Hixon Sgt James R Jr
> > Cc: 'Luobin Yang'; '[EMAIL PROTECTED]'
> > Subject: Re: Why the route in BGP table doesn't appear in IP table.
> >
> >
> >
> > A little confusing below, 99% right, but "no sync" causes the IGP and EGP
> > to not be in sync and is probably what you want in most cases, like
> > multihoming to multiple ISP's etc.
> >
> > On Thu, 17 Aug 2000, Hixon Sgt James R Jr wrote:
> >
> > > The reason for this is because your EGP is not synchronized
>with your IGP.
> > > By default BGP will not redistribute those routes learned into the IGP.
> > This
> > > is good because it allows for scalability issues to be resolved
>with this.
> > A
> > > way to bypass this is by redistributing networks, redistributing static,
> > and
> > > also by the statement no synchronization under your BGP statement.
> > However,
> > > this is not a great idea to do on an Enterprise network connecting to two
> > or
> > > more ISP's. For more information- I think it is in Jeff Doyles' Routing
> > > TCP/IP Vol I. If not, you can learn allot more about it using the
> > following
> > > link.
> > >
> > > http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/icsbgp4.htm
> > >
> > > Hope this helps
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Luobin Yang [mailto:[EMAIL PROTECTED]]
> > > Sent: Wednesday, August 16, 2000 10:00 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Why the route in BGP table doesn't appear in IP table.
> > >
> > >
> > > I found a lot times, some routes in BGP table don't show up in IP table.
> > > When I use "show ip bgp", I can see the route to a destination, but when
> > > I use "sh ip route", I can't find the route to the destination. Does
> > > anybody know the reason?
> > >
> > >
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> >
> > -----------------------------------------------
> > Brian Feeny, CCNA, CCDA [EMAIL PROTECTED]
> > Network Administrator
> > ShreveNet Inc. (ASN 11881)
> >
> > ___________________________________
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> >
>
>-----------------------------------------------
>Brian Feeny, CCNA, CCDA [EMAIL PROTECTED]
>Network Administrator
>ShreveNet Inc. (ASN 11881)
>
>___________________________________
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