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Re: BGP Flapping routes posted 08/18/2003
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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@xxxxxxxxxxx>
To: <ccielab@xxxxxxxxxxxxxx>
Cc: <matijevi@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
> >To: "Larry Cain" <l_u_cain@xxxxxxxxxxx>,<ccielab@xxxxxxxxxxxxxx>
> >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@xxxxxxxxxxx>
> To: <ccielab@xxxxxxxxxxxxxx>
> 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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