From: Anthony Sequeira (terry.francona@gmail.com)
Date: Sat Dec 03 2005 - 12:34:50 GMT-3
OF COURSE!
I guess at some point I know BGP well enough where I can answer my own damn
questions!
As always - thanks Brian, Scott and all the rest here!
On 12/3/05, Brian Dennis <bdennis@internetworkexpert.com> wrote:
>
> Anthony,
> You need to add eBGP multihop to your configuration since you
> changed the next hop to an IP address that isn't directly connected.
>
> <config>
> router bgp 1
> no synchronization
> neighbor 136.1.12.2 remote-as 2
> neighbor 136.1.12.2 route-map SET->NEXT->HOP in
> no auto-summary
> !
> route-map SET->NEXT->HOP permit 10
> set ip next-hop 150.2.2.2
> </config>
>
>
> Rack2R1#sho ip bgp 172.16.0.0
> BGP routing table entry for 172.16.0.0/16, version 0
> Paths: (1 available, no best path)
> Not advertised to any peer
> 2
> 150.2.2.2 (inaccessible) from 136.1.12.2 (150.2.2.2)
> Origin IGP, metric 0, localpref 100, valid, external
> Rack2R1#conf t
> Enter configuration commands, one per line. End with CNTL/Z.
> Rack2R1(config)#router bgp 1
> Rack2R1(config-router)#neighbor 136.1.12.2 ebgp-multihop 10
> Rack2R1(config-router)#^Z
> Rack2R1#
> Rack2R1#clear ip bgp *
> Rack2R1#
> *Mar 1 00:59:11.201: %BGP-5-ADJCHANGE: neighbor 136.1.12.2 Down User
> reset
> *Mar 1 00:59:49.403: %BGP-5-ADJCHANGE: neighbor 136.1.12.2 Up
> Rack2R1#sho ip bgp 172.16.0.0
> BGP routing table entry for 172.16.0.0/16, version 2
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
> Flag: 0x820
> Not advertised to any peer
> 2
> 150.2.2.2 (metric 11) from 136.1.12.2 (150.2.2.2)
> Origin IGP, metric 0, localpref 100, valid, external, best
> Rack2R1#
>
>
> HTH,
>
> Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> bdennis@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Direct: 775-745-6404 (Outside the US and Canada)
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Anthony Sequeira
> Sent: Friday, December 02, 2005 9:17 PM
> To: swm@emanon.com
> Cc: Cisco certification
> Subject: Re: No Best Path with BGP
>
> Yes there was full reachability in the underlying IGP to all routes.
>
> R2 has a route to the loopback of R5.
>
> Why in the world would it say 150.1.5.5 (inaccessible) from 136.1.245.5
> (
> 150.1.5.5)?
>
> This is saying the Lo0 interface of R5 is unreachable from the
> Serial0/0.245
> subinterface of R5.
>
> You would think it would say Lo0 interface of R5 is unreachable from an
> interface of R2.
>
> Damn - I wish I had not gotten kicked off right when I doscvered this
> problem! These captures were all I was able to retrieve.
>
> Thanks everyone for trying to help here. . .
>
>
> On 12/2/05, Scott Morris <swm@emanon.com> wrote:
> >
> > Is 150.1.5.5 in the routing table?
> >
> > More importantly, is it in there with something other than a default
> route
> > to get to it?
> >
> > Seems the router is telling you the problem. :) But of course, right
> at
> > the end of time doesn't exactly help in testing things, does it!
> >
> > Scott
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Anthony Sequeira
> > Sent: Friday, December 02, 2005 8:42 PM
> > To: Cisco certification
> > Subject: No Best Path with BGP
> >
> > Wow - is this interesting....sadly it happened right as I got kicked
> off
> > my
> > rental rack today....so I need the expertise of the group to help me
> > understand.....
> >
> > Simple BGP topology......
> >
> > R5(AS 200) -------------R2(AS 300)
> >
> > I wanted to use a route-map to change the next-hop value of incoming
> > routes
> > from R5 so that the next hop will be the loopback of R5. By the way -
> I
> > had
> > best paths and everything was fine before trying this change....
> >
> > R2#
> > !
> > router bgp 300
> > no synchronization
> > neighbor 136.1.245.5 remote-as 200
> > neighbor 136.1.245.5 route-map HOPPER in no auto-summary !
> > route-map HOPPER permit 10
> > set ip next-hop 150.1.5.5
> >
> > After this config - the next hop does change - but now no BEST PATHs:
> >
> > R2#show ip bgp
> > BGP table version is 7, local router ID is 150.1.2.2 Status codes: s
> > suppressed, d damped, h history, * valid, > best, i - internal,
> > r RIB-failure, S Stale
> > Origin codes: i - IGP, e - EGP, ? - incomplete
> >
> > Network Next Hop Metric LocPrf Weight Path
> > * 205.90.31.0 150.1.5.5 0 200 254 ?
> > * 220.20.3.0 150.1.5.5 0 200 254 ?
> > * 222.22.2.0 150.1.5.5 0 200 254 ?
> > I try and get some details:
> >
> > R2#show ip bgp 222.22.2.0
> > BGP routing table entry for 222.22.2.0/24, version 7
> > Paths: (1 available, no best path)
> > Not advertised to any peer
> > 200 254
> > 150.1.5.5 (inaccessible) from 136.1.245.5 (150.1.5.5)
> > Origin incomplete, localpref 100, valid, external
> >
> > OK - so 150.1.5.5 is inaccessible from 136.1.245.5? My goodness -
> these
> > interfaces are on the same router! What gives? Could it be that
> > 136.1.245.5is a Frame Relay interface that is not pingable from the
> > loopback
> > address ( 150.1.5.5)? OK - I know I am reaching - but I am tired after
> 10
> > hours on the rack.....
> >
> > Can anyone help?
> >
> >
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