From: Peter van Oene (pvo@xxxxxxxxxxxx)
Date: Tue Jan 01 2002 - 04:11:24 GMT-3
Its really an OSPF Rid vs BGP peer id issue here. There is no routing loop
to speak of.
At 01:59 PM 1/1/2002 +1100, you wrote:
>Hi All,
> >From what I see in the IP routing table, there is a loop for destination
>137.6.2.10.
>The next-hop for 5.0.0.0 in the BGP table is 137.6.2.17, so a recursive
>lookup
>for this destination in the IP routing table results in 137.6.2.10 as the
>next-hop.
>We still require another recursive lookup to decide which interface to
>switch the
>traffic to, and this results in 137.6.2.10 with a next-hop of 137.6.2.10
>(loop).
>Serial0/0 is still noted as the outgoing interface, so whatever is on the
>other end
>of Serial0/0 will receive the packet at layer2 & (most likely) has the same
>issue
>for the layer3 destination, and switch it back out the incoming interface.
>
>I would clear ip route * and clear ip bgp *, debug reconvergance &
>check again.
>
>Brett.
>
>----- Original Message -----
>From: "Peter van Oene" <pvo@usermail.com>
>To: <ccielab@groupstudy.com>
>Sent: Tuesday, January 01, 2002 8:47 AM
>Subject: RE: BGP routes.
>
>
> > As others have found before, OSPF RID and BGP Peer Address must match when
> > running synchronized. Though I still can't for the life of me figure out
> > why you guys test 9-10 year old commands. You just might give the
> > otherwise sane proctors a reason to test you on this antique stuff.
> >
> >
> >
> >
> >
> > >At 01:53 PM 12/31/2001 +0000, you wrote:
> > >>Parry,
> > >>
> > >>Here's the BGP table and routing table along with the output from one of
> > >>the prefixes not being marked as best.
> > >>
> > >>As you see the route has a next hop of 137.6.2.17 from router with RID
>of
> > >>137.6.2.2. Both these prefixes are in the main routing table so my
> > >>understanding was that the route should be marked best. I know I can
> > >>turn off synchronization and get it to work but I didn't think I had to
> > >>if the next hop was reachable. If I have to do a no sync then fine and
> > >>my understanding of the rule is at fault.
> > >>
> > >>Thanks, Stephen.
> > >>
> > >> Network Next Hop Metric LocPrf Weight Path
> > >>* i0.0.0.0 137.6.2.9 100 0 i
> > >>* i5.0.0.0 137.6.2.17 0 100 0 111 100 i
> > >>* i6.0.0.0 137.6.2.17 0 100 234 100 i
> > >>* i7.0.0.0 137.6.2.17 0 100 0 100 i
> > >>* i137.6.1.1/32 137.6.2.17 0 100 0 100 i
> > >>* i137.6.2.2/32 137.6.2.9 0 100 0 i
> > >>* i137.6.2.8/29 137.6.2.10 0 100 0 i
> > >>*> 0.0.0.0 0 32768 i
> > >>* i137.6.2.16/30 137.6.2.9 0 100 0 i
> > >>*> 137.6.3.3/32 0.0.0.0 0 32768 i
> > >>* 137.6.3.16/28 137.6.3.18 0 0 300 i
> > >>*> 0.0.0.0 0 32768 i
> > >>2612#show ip bgp 5.0.0.0
> > >>BGP routing table entry for 5.0.0.0/8, version 0
> > >>Paths: (1 available, no best path)
> > >> Not advertised to any peer
> > >> 111 100
> > >> 137.6.2.17 (metric 176) from 137.6.2.10 (137.6.2.2)
> > >> Origin IGP, metric 0, localpref 100, valid, internal, not
>synchronized
> > >> Originator: 137.6.2.2, Cluster list: 137.6.5.5
> > >>2612#show ip route
> > >>Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
> > >> D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> > >> N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> > >> E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
> > >> i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
> > >> inter area
> > >> * - candidate default, U - per-user static route, o - ODR
> > >> P - periodic downloaded static route
> > >>
> > >>Gateway of last resort is not set
> > >>
> > >> 137.6.0.0/16 is variably subnetted, 9 subnets, 4 masks
> > >>O 137.6.2.9/32 [110/128] via 137.6.2.10, 00:04:25, Serial0/0
> > >>C 137.6.2.8/29 is directly connected, Serial0/0
> > >>O 137.6.2.10/32 [110/64] via 137.6.2.10, 00:04:25, Serial0/0
> > >>O IA 137.6.2.2/32 [110/129] via 137.6.2.10, 00:02:30, Serial0/0
> > >>O IA 137.6.5.5/32 [110/65] via 137.6.2.10, 00:02:30, Serial0/0
> > >>O E2 137.6.1.1/32 [110/78] via 137.6.2.10, 00:02:30, Serial0/0
> > >>C 137.6.3.3/32 is directly connected, Loopback0
> > >>C 137.6.3.16/28 is directly connected, Ethernet0/0
> > >>O 137.6.2.16/30 [110/176] via 137.6.2.10, 00:04:26, Serial0/0
> > >>O E2 5.0.0.0/8 [110/78] via 137.6.2.10, 00:02:31, Serial0/0
> > >>O E2 6.0.0.0/8 [110/78] via 137.6.2.10, 00:02:31, Serial0/0
> > >>O E2 7.0.0.0/8 [110/78] via 137.6.2.10, 00:02:31, Serial0/0
> > >>2612#
> > >>
> > >>
> > >>>From: "Chua, Parry" <Parry.Chua@compaq.com>
> > >>>To: "Stephen Oliver" <stevie_oliver@hotmail.com>,
> > >>><fred190044@hotmail.com>, <ccielab@groupstudy.com>
> > >>>Subject: RE: BGP routes.
> > >>>Date: Mon, 31 Dec 2001 08:59:53 +0800
> > >>>
> > >>>Hi,
> > >>>
> > >>>Do a show ip bgp a.b.c.d and see nwhat is the reason that it is NOT the
> > >>>best route,
> > >>>if it is "no sync" and the route of a.b.c.d is from ospf, then you
> > >>>should check the RID
> > >>>of the network a.b.c.d
> > >>>
> > >>> > Parry Chua
> > >>> >
> > >>>
> > >>>
> > >>>-----Original Message-----
> > >>>From: Stephen Oliver [mailto:stevie_oliver@hotmail.com]
> > >>>Sent: Saturday, December 29, 2001 7:02 PM
> > >>>To: fred190044@hotmail.com; ccielab@groupstudy.com
> > >>>Subject: Re: BGP routes.
> > >>>
> > >>>
> > >>>Fred,
> > >>>
> > >>>Well, for example, the 5.0.0.0 route is in the bgp table with next hop
> > >>>as
> > >>>137.6.2.17. This route is in the routing table, 137.6.2.16/30 but the
>5
> > >>>
> > >>>prefix is not marked as best in the bgp table. I am trying to do this
> > >>>by
> > >>>not setting no sync just to test the bgp rules. I thought that since
> > >>>the
> > >>>next hop is reachable through an IGP then it would be marked as *> in
> > >>>the
> > >>>bgp table. I can get the route to be marked as *> by setting no sync
> > >>>but I
> > >>>wanted to avoid using this if I could. I probably just misunderstand
> > >>>the
> > >>>synchronization rule.
> > >>>
> > >>>Thanks, Stephen.
> > >>>
> > >>>
> > >>> >From: "Fred Danson" <fred190044@hotmail.com>
> > >>> >To: ccielab@groupstudy.com
> > >>> >CC: stevie_oliver@hotmail.com
> > >>> >Subject: Re: BGP routes.
> > >>> >Date: Fri, 28 Dec 2001 09:42:48 -0500
> > >>> >
> > >>> >Which prefix is not working properly? Do you have "no sync" set in
>this
> > >>>
> > >>> >router? Would you mind posting your configs?
> > >>> >
> > >>> >
> > >>> >>From: "Stephen Oliver" <stevie_oliver@hotmail.com>
> > >>> >>Reply-To: "Stephen Oliver" <stevie_oliver@hotmail.com>
> > >>> >>To: ccielab@groupstudy.com
> > >>> >>Subject: BGP routes.
> > >>> >>Date: Fri, 28 Dec 2001 12:09:54 +0000
> > >>> >>
> > >>> >>I have a BGP network with OSPF running along side. A loopback
> > >>>propogates
> > >>> >>through the BGP tables but on one router it is not installed as best
> > >>>even
> > >>> >>though OSPF provides a route to the next hop in the routing table.
>I
> > >>> >>thought if this criteria was met the BGP table would mark the route
>as
> > >>> >
> > >>> >>for
> > >>> >>best. The routing and BGP tables are below.
> > >>> >>
> > >>> >>Any ideas ?
> > >>> >>
> > >>> >>Thanks, Stephen.
> > >>> >>
> > >>> >>Gateway of last resort is not set
> > >>> >>
> > >>> >> 137.6.0.0/16 is variably subnetted, 9 subnets, 4 masks
> > >>> >>O 137.6.2.9/32 [110/128] via 137.6.2.10, 00:00:12, Serial0/0
> > >>> >>C 137.6.2.8/29 is directly connected, Serial0/0
> > >>> >>O 137.6.2.10/32 [110/64] via 137.6.2.10, 00:41:05, Serial0/0
> > >>> >>O IA 137.6.2.2/32 [110/129] via 137.6.2.10, 00:08:44, Serial0/0
> > >>> >>O E2 137.6.1.1/32 [110/78] via 137.6.2.10, 00:08:44, Serial0/0
> > >>> >>O IA 137.6.5.5/32 [110/65] via 137.6.2.10, 00:08:44, Serial0/0
> > >>> >>C 137.6.3.3/32 is directly connected, Loopback0
> > >>> >>C 137.6.3.16/28 is directly connected, Ethernet0/0
> > >>> >>O 137.6.2.16/30 [110/176] via 137.6.2.10, 00:41:06, Serial0/0
> > >>> >>O E2 5.0.0.0/8 [110/78] via 137.6.2.10, 00:08:46, Serial0/0
> > >>> >>O E2 6.0.0.0/8 [110/78] via 137.6.2.10, 00:08:46, Serial0/0
> > >>> >>O E2 7.0.0.0/8 [110/78] via 137.6.2.10, 00:08:46, Serial0/0
> > >>> >>2612#show ip bgp
> > >>> >>BGP table version is 4, local router ID is 137.6.3.3
> > >>> >>Status codes: s suppressed, d damped, h history, * valid, > best,
>i -
> > >>> >>internal
> > >>> >>Origin codes: i - IGP, e - EGP, ? - incomplete
> > >>> >>
> > >>> >> Network Next Hop Metric LocPrf Weight Path
> > >>> >>* i5.0.0.0 137.6.2.17 0 100 0 111 100
>i
> > >>> >>* i6.0.0.0 137.6.2.17 0 100 0 100 i
> > >>> >>* i7.0.0.0 137.6.2.17 0 100 0 100 i
> > >>> >>* i137.6.1.1/32 137.6.2.17 0 100 0 100 i
> > >>> >>* i137.6.2.2/32 137.6.2.9 0 100 0 i
> > >>> >>* i137.6.2.8/29 137.6.2.10 0 100 0 i
> > >>> >>*> 0.0.0.0 0 32768 i
> > >>> >>* i137.6.2.16/30 137.6.2.9 0 100 0 i
> > >>> >>*> 137.6.3.3/32 0.0.0.0 0 32768 i
> > >>> >>* 137.6.3.16/28 137.6.3.18 0 0 300 i
> > >>> >>*> 0.0.0.0 0 32768 i
> > >>> >>
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