From: John Matijevic (matijevi@bellsouth.net)
Date: Tue Aug 19 2003 - 10:33:21 GMT-3
Hello Larry,
Im curious as to where you made the changes, could you please post the
changes you made, to get it to work.
Sincerely,
Matijevic
----- Original Message -----
From: "Larry Cain" <l_u_cain@hotmail.com>
To: <ccielab@groupstudy.com>
Cc: <dswink@cisco.com>
Sent: Tuesday, August 19, 2003 7:26 AM
Subject: RE: BGP Flapping routes
> Hi Dave
>
> Thanks for your input. Changing the ADs for BGP cured the problem.
> Sorry about leaving bits out of the config, trying to make it short and
> concise, went a bit over the top.
>
> Decided to go with AD change rather than route filtering as suggested by
> MMoniz (sorry I don't know your first name), as it seems a lot easier.
> But which way would be the best, I suppose a question to the proctor would
> be in order.
>
> Thank you for all your input.
> Back to making something just as stupid up, with the hope that it might
come
> up.
>
> Cheers
>
> Larry
>
>
> >From: "Dave Swink \(dswink\)" <dswink@cisco.com>
> >Reply-To: <dswink@cisco.com>
> >To: "'Larry Cain'" <l_u_cain@hotmail.com>
> >CC: <ccielab@groupstudy.com>
> >Subject: RE: BGP Flapping routes
> >Date: Mon, 18 Aug 2003 17:42:03 -0500
> >
> >Larry,
> >
> >I think you have cut out some other important lines in the configs. R2
> >and R3 peer in BGP because EIGRP has a route to 2.2.2.0 and 3.3.3.0 (you
> >do not show "network 3.3.3.0 0.0.0.255" under the EIGRP process in R3,
> >but it must be there from the routing table behavior). EIGRP on R3
> >offers a route to 2.2.2.0 via 10.1.3.2 with an administrative distance
> >of 90, which is good, since 10.1.3.2 is indeed the next hop. BGP uses
> >this routing to peer R2 and R3. Then BGP on R3 proclaims that it also
> >has a route to 2.2.2.0 via 2.2.2.2 with an administrative distance of
> >just 20, so it replaces the EIGRP route.
> >
> >Problem: R3 now has a route to 2.2.2.0 via 2.2.2.2, but it does not know
> >a working route to 2.2.2.2, the supposed next hop anymore! So BGP times
> >out, the peering breaks and the EIGRP route takes over again.
> >
> >Now that sensible routing has been restored, the BGP routers will peer
> >up again and the flap-o-rama is going again.
> >
> >In real life, you would use a static route to point to the next hop to
> >the BGP peer. BGP's external AD of 20 will not over rule a static
> >route's AD of 1. In your lab, you could just change the AD of the BGP
> >routes to the loopback subnets to 91.
> >
> >Fun lab.
> >
> >Dave Swink
> >
> >
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >Larry Cain
> >Sent: Monday, August 18, 2003 4:04 PM
> >To: ccielab@groupstudy.com
> >Cc: matijevi@bellsouth.net
> >Subject: Re: BGP Flapping routes
> >
> >
> >Hi John
> >
> >Already done, took it out of the configs to make them shorter - sorry.
> >Also have put next-hop-self in as well to all neighbours. Restarted all
> >bgp processes. Have tried this with similar topologies and different
> >routing protocols with
> >no success.
> >It seems to be a problem with redistributing, but WHERE???!!
> >
> >Any ideas, comments much appreciated.
> >
> >Larry
> >
> >
> > >From: "John Matijevic" <matijevi@bellsouth.net>
> > >To: "Larry Cain" <l_u_cain@hotmail.com>,<ccielab@groupstudy.com>
> > >Subject: Re: BGP Flapping routes
> > >Date: Mon, 18 Aug 2003 15:32:25 -0400
> > >
> > >Hello Larry,
> > >This looks like a tricky issue, lets start by adding the following to
> > >your BGP configs on all routers, neighbor ip-address update-source lo0
> > >restart your bgp process,
> > >and post results.
> > >Sincerely,
> > >Matijevic
> > >----- Original Message -----
> > >From: "Larry Cain" <l_u_cain@hotmail.com>
> > >To: <ccielab@groupstudy.com>
> > >Cc: <matijevi@bellsouth.net>
> > >Sent: Monday, August 18, 2003 2:44 PM
> > >Subject: Re: BGP Flapping routes
> > >
> > >
> > > > Hi John
> > > >
> > > > Here is info you asked for.
> > > > Hope it helps.
> > > > 2 versions of routing and bgp tables.
> > > > First is with the tables with all info including BGP in them. The
> > > > second
> > >is
> > > > without the BGP routes.
> > > > You will notice that certain routes are either learnt by BGP or the
> > > > IGP,
> > >or
> > > > disappear all together.
> > > > the routes will then reappear or cahnged to a learnt BGP route. This
> >
> > > > happens every 60s, regular as clockwork - well as regualar as Cisco
> > > > routers can get. The top bgp table goes with the top routing table.
> > > >
> > > > Many thanks for your help
> > > >
> > > > Larry
> > > >
> > > > r1#sh ip ro
> > > > C 1.1.1.0 is directly connected, Loopback0
> > > > O 2.2.2.0 [110/65] via 10.1.2.2, 00:26:40, Serial0
> > > > B 3.3.3.0 [200/0] via 2.2.2.2, 00:00:13
> > > > O E2 10.1.3.0 [110/5] via 10.1.2.2, 00:26:40, Serial0
> > > > C 10.1.2.0 is directly connected, Serial0
> > > > C 10.1.1.0 is directly connected, Ethernet0
> > > > O E2 10.1.4.0 [110/5] via 10.1.2.2, 00:26:40, Serial0
> > > >
> > > > C 1.1.1.0 is directly connected, Loopback0
> > > > O 2.2.2.0 [110/65] via 10.1.2.2, 00:38:19, Serial0
> > > > O E2 3.3.3.0 [110/5] via 10.1.2.2, 00:00:52, Serial0
> > > > O E2 10.1.3.0 [110/5] via 10.1.2.2, 00:38:19, Serial0
> > > > C 10.1.2.0 is directly connected, Serial0
> > > > C 10.1.1.0 is directly connected, Ethernet0
> > > > O E2 10.1.4.0 [110/5] via 10.1.2.2, 00:38:19, Serial0
> > > >
> > > > r2#sh ip ro
> > > > B 1.1.1.0/24 [200/0] via 1.1.1.1, 00:12:04
> > > > C 2.2.2.0 is directly connected, Loopback0
> > > > B 3.3.3.0 [20/0] via 3.3.3.3, 00:00:05
> > > > C 10.1.3.0 is directly connected, Serial1
> > > > C 10.1.2.0 is directly connected, Serial0
> > > > O 10.1.1.0 [110/51] via 10.1.2.1, 00:22:32, Serial0
> > > > D 10.1.4.0 [90/307200] via 10.1.3.3, 00:33:33, Serial1
> > > >
> > > > B 1.1.1.0/24 [200/0] via 1.1.1.1, 00:11:16
> > > > C 2.2.2.0 is directly connected, Loopback0
> > > > D 3.3.3.0 [90/409600] via 10.1.3.3, 00:00:16, Serial1
> > > > C 10.1.3.0 is directly connected, Serial1
> > > > C 10.1.2.0 is directly connected, Serial0
> > > > O 10.1.1.0 [110/51] via 10.1.2.1, 00:21:43, Serial0
> > > > D 10.1.4.0 [90/307200] via 10.1.3.3, 00:32:45, Serial1
> > > >
> > > > R3#sh ip ro
> > > > B 1.1.1.0/24 [20/0] via 2.2.2.2, 00:00:26
> > > > B 2.2.2.0 [20/0] via 2.2.2.2, 00:00:27
> > > > C 3.3.3.0 is directly connected, Loopback0
> > > > C 10.1.3.0 is directly connected, Serial1
> > > > D EX 10.1.2.0 [170/2560025856] via 10.1.3.2, 00:34:57, Serial1
> > > > D EX 10.1.1.0 [170/2560025856] via 10.1.3.2, 00:23:41, Serial1
> > > > C 10.1.4.0 is directly connected, Ethernet0
> > > >
> > > > D EX 2.2.2.0 [170/2560025856] via 10.1.3.2, 00:00:47, Serial1
> > > > C 3.3.3.0 is directly connected, Loopback0
> > > > C 10.1.3.0 is directly connected, Serial1
> > > > D EX 10.1.2.0 [170/2560025856] via 10.1.3.2, 00:36:15, Serial1
> > > > D EX 10.1.1.0 [170/2560025856] via 10.1.3.2, 00:25:00, Serial1
> > > > C 10.1.4.0 is directly connected, Ethernet0
> > > >
> > > >
> > > > r1#sh ip bg
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > *> 1.1.1.0/24 0.0.0.0 0 32768 i
> > > > *>i2.2.2.0/24 2.2.2.2 0 100 0 i
> > > > *>i3.3.3.0/24 2.2.2.2 0 100 0 65200 i
> > > >
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > *> 1.1.1.0/24 0.0.0.0 0 32768 i
> > > > *>i2.2.2.0/24 2.2.2.2 0 100 0 i
> > > >
> > > > r2#sh ip bg
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > *>i1.1.1.0/24 1.1.1.1 0 100 0 i
> > > > *> 2.2.2.0/24 0.0.0.0 0 32768 i
> > > > *> 3.3.3.0/24 3.3.3.3 0 0 65200 I
> > > >
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > *>i1.1.1.0/24 1.1.1.1 0 100 0 i
> > > > *> 2.2.2.0/24 0.0.0.0 0 32768 i
> > > > * 3.3.3.0/24 3.3.3.3 0 0 65200 i
> > > >
> > > > r3#sh ip bg
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > *> 1.1.1.0/24 2.2.2.2 0 65100 i
> > > > *> 2.2.2.0/24 2.2.2.2 0 0 65100 i
> > > > *> 3.3.3.0/24 0.0.0.0 0 32768 i
> > > >
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > * 1.1.1.0/24 2.2.2.2 0 65100 i
> > > > * 2.2.2.0/24 2.2.2.2 0 0 65100 i
> > > > *> 3.3.3.0/24 0.0.0.0 0 32768 i
> > > >
> > > >
> > > > >From: "John Matijevic" <matijevi@bellsouth.net>
> > > > >To: "Larry Cain" <l_u_cain@hotmail.com>,<ccielab@groupstudy.com>
> > > > >Subject: Re: BGP Flapping routes
> > > > >Date: Mon, 18 Aug 2003 12:46:09 -0400
> > > > >
> > > >
> > > >
> > > > Hello Larry,
> > > > Im not quite understanding what the problem is in particular the
> > >following:
> > > > The BGP routes from other AS (loopbacks) are in the table for 60s
> > > > with
> > >*>,
> > > > then 60s with only > on both R2 and R3.
> > > > R1 only sees R3 loop when R2 has *> (obviously).
> > > > Can you please try to rephrase what you mean here?
> > > > Also could you post sh ip route, and sh ip bgp, on all 3 routers?
> > > > Sincerely, Matijevic
> > > > ----- Original Message -----
> > > > From: "Larry Cain" <l_u_cain@hotmail.com>
> > > > To: <ccielab@groupstudy.com>
> > > > Sent: Monday, August 18, 2003 12:34 PM
> > > > Subject: BGP Flapping routes
> > > >
> > > >
> > > > >Hi Group
> > > > >
> > > > >Have got a BGP route flapping route problem.
> > > > >
> > > > >R1 and R2 talking OSPF. R2 and R3 talking eigrp. They are
> > >redistributing
> > > > >both ways.
> > > > >IGP routing tables are correct on R1 and R3 - seeing all networks
> > > > including
> > > > >remote e0 networks.
> > > > >R1 and R2 in same AS 65100. R3 in AS 65200.
> > > > >Only Loopbacks put into BGP.
> > > > >
> > > > >
> > > > >|--e0--R1----s0----R2----s1----R3--e0--|
> > > > >
> > > > >---------OSPF--------|---------eigrp--------
> > > > >
> > > > >|------bgp65100------| |--bgp65200--|
> > > > >
> > > > >The BGP routes from other AS (loopbacks) are in the table for 60s
> > > > >with
> > >*>,
> > > > >then 60s with only > on both R2 and R3.
> > > > >R1 only sees R3 loop when R2 has *> (obviously).
> > > > >
> > > > >As I say this happens every minute.
> > > > >Please help!!!!
> > > > >
> > > > >Configs below:
> > > > >
> > > > >All the best
> > > > >
> > > > >Larry
> > > > >
> > > > >ROUTER R1
> > > > >interface Loopback0
> > > > >ip address 1.1.1.1 255.255.255.0
> > > > >!
> > > > >interface Ethernet0
> > > > >ip address 10.1.1.1 255.255.255.0
> > > > >!
> > > > >interface Serial0
> > > > >ip address 10.1.2.1 255.255.255.0
> > > > >!
> > > > >router ospf 1
> > > > >network 1.1.1.0 0.0.0.255 area 0
> > > > >network 10.0.0.0 255.0.0.0 area 0
> > > > >!
> > > > >router bgp 65100
> > > > >network 1.1.1.0 mask 255.255.255.0
> > > > >neighbor 2.2.2.2 remote-as 65100
> > > > >no auto-summary
> > > > >!
> > > > >
> > > > >ROUTER R2
> > > > >interface Loopback0
> > > > >ip address 2.2.2.2 255.255.255.0
> > > > >!
> > > > >interface Serial0
> > > > >ip address 10.1.2.2 255.255.255.0
> > > > >!
> > > > >interface Serial1
> > > > >ip address 10.1.3.2 255.255.255.0
> > > > >!
> > > > >router ospf 1
> > > > >redistribute eigrp 1 metric 5 subnets
> > > > >network 2.2.2.0 0.0.0.255 area 0
> > > > >network 10.1.2.0 0.0.0.255 area 0
> > > > >!
> > > > >router eigrp 1
> > > > >redistribute ospf 1 metric 1 1 1 1 1
> > > > >network 10.1.3.0 0.0.0.255
> > > > >!
> > > > >router bgp 65100
> > > > >network 2.2.2.0 mask 255.255.255.0
> > > > >neighbor 1.1.1.1 remote-as 65100
> > > > >neighbor 3.3.3.3 remote-as 65200
> > > > >no auto-summary
> > > > >!
> > > > >
> > > > >ROUTER R3
> > > > >interface Loopback0
> > > > >ip address 3.3.3.3 255.255.255.0
> > > > >!
> > > > >interface Ethernet0
> > > > >ip address 10.1.4.3 255.255.255.0
> > > > >!
> > > > >interface Serial1
> > > > >ip address 10.1.3.3 255.255.255.0
> > > > >!
> > > > >router eigrp 1
> > > > >redistribute ospf 1 metric 1 1 1 1 1
> > > > >network 10.1.3.0 0.0.0.255
> > > > >network 10.1.4.0 0.0.0.255
> > > > >no auto-summary
> > > > >!
> > > > >router bgp 65200
> > > > >network 3.3.3.0 mask 255.255.255.0
> > > > >neighbor 2.2.2.2 remote-as 65100
> > > > >no auto-summary
> > > > >!
> > > > >
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