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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> FAQ, list archives, and subscription info: http://www.groupstudy.com
> Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>
-----------------------------------------------
Brian Feeny, CCNA, CCDA [EMAIL PROTECTED]
Network Administrator
ShreveNet Inc. (ASN 11881)
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