From: Nigel Roy (nigel@xxxxxxxxxxxxxxxxx)
Date: Fri Nov 16 2001 - 05:39:53 GMT-3
Chua,
This is not based on any documentation just a lot of playing around and
testing that led to the conclusion of those particular rules.
regards
Nigel
----- Original Message -----
From: "Chua, Parry" <Parry.Chua@compaq.com>
To: "Nigel Roy" <nigel@system-link.co.uk>
Sent: Friday, November 16, 2001 1:39 AM
Subject: RE: OSPF redistribution into BGP, no external routes shown.
Hi Roy,
Are you refer to the BGP path selection logic that post on CCO ?
If not, it this refer to any refernce doc ?
Parry Chua
-----Original Message-----
From: Nigel Roy [mailto:nigel@system-link.co.uk]
Sent: Friday, November 16, 2001 6:35 AM
To: ccielab@groupstudy.com
Cc: Albert Lu
Subject: Re: OSPF redistribution into BGP, no external routes shown.
Albert,
The problem is not that the route has come from an external source, as
you
say it is quite acceptable for "external" routes to be redistributed.
However the problem here is that the route has not been learned by OSPF
nor
is it in a network statement. Although OSPF will advertise it out as an
external LSA it cannot be redistributed from OSPF to BGP on the same
router
as which it was redistributed from another source (connected). As I
said
earlier this is because when you redistribute routes from one protocol
to
another there are strict rules as to what will be taken:
1) a)The route must have been learned by this router by the source
protocol
(OSPF in your case)
or b)The route must be in a network statement under the source process.
2) The route must be in the IP routing table from that process.
I hope this clarifies it!
regards
Nigel (CCIE #1405)
----- Original Message -----
From: "Albert Lu" <albert_ccie@yahoo.com>
To: "'Nigel Roy'" <nigel@system-link.co.uk>
Cc: <ccielab@groupstudy.com>
Sent: Thursday, November 15, 2001 9:05 PM
Subject: RE: OSPF redistribution into BGP, no external routes shown.
> Nigel,
>
> That is correct, I'm trying to redistribute the connected loopback of
> 150.50.4.0 into OSPF and redistribute it into BGP.
>
> I'm sure that it must be ok for OSPF to redistribute it's external
routes
> into BGP. In the real world, an AS would probably consist of more than
1
> routing protocol (eg. OSPF + EIGRP). If OSPF has the job of
redistributing
> into BGP, then no EIGRP routes would be redistributed.
>
> That doesn't quite make sense for me, but please correct me.
>
> Thanks
>
> Albert
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Nigel Roy
> Sent: Friday, November 16, 2001 1:29 AM
> To: ccielab@groupstudy.com
> Subject: Fw: OSPF redistribution into BGP, no external routes shown.
>
>
> Albert,
>
> From what I can gather you are trying to do the following:
>
> redistribute connected into OSPF and then from OSPF into BGP.
>
> Unfortunately the only routes that will get redistributed from OSPF
into
> BGP
> are routes that have been learned by OSPF or have a network statement
under
> the OSPF. They must also be the best route as per the IP routing
table.
> You cannot get routes from one protocol to be redistributed into
another
> and
> then forwarded onto a third protocol. This prevents the possibility
of
> mutual redistribution causing routes be fed back into their
originating
> protocol.
>
> regards
>
> Nigel
>
>
>
>
> ----- Original Message -----
> From: "Albert Lu" <albert_ccie@yahoo.com>
> To: <ccielab@groupstudy.com>
> Sent: Thursday, November 15, 2001 12:18 PM
> Subject: OSPF redistribution into BGP, no external routes shown.
>
>
> > Hello all,
> >
> > Does anyone know any reason why OSPF external routes would not
> redistribute
> > into BGP?
> >
> > Here's a section of the config, and the show ip ospf database. The
ospf
> > > database shows that the connected route has been redistributed
into
OSPF
> > as
> > > External, but it seems like BGP won't accept this route when
> redistributed
> > > from OSPF.
> > >
> > > Thanks
> > >
> > > Albert
> > >
> > > interface Loopback0
> > > ip address 200.0.0.8 255.255.255.255
> > > !
> > > interface Loopback1
> > > ip address 150.50.3.8 255.255.255.0
> > > ip ospf network point-to-point
> > > !
> > > interface Loopback2
> > > ip address 150.50.4.8 255.255.255.0
> > > ip ospf network
> > >
> > > router ospf 8
> > > log-adjacency-changes
> > > redistribute connected metric-type 1 subnets route-map
RM_150_50_4_Only
> > > passive-interface Loopback1
> > > network 150.50.3.0 0.0.0.255 area 0
> > > network 150.50.5.64 0.0.0.63 area 0
> > > !
> > > router bgp 65078
> > > bgp log-neighbor-changes
> > > bgp confederation identifier 200
> > > redistribute ospf 8 match internal external 1 external 2
route-map
> O_IN_B
> > > neighbor 150.50.5.68 remote-as 65078
> > > no auto-summary
> > > !
> > > !
> > > access-list 10 permit 150.50.4.0
> > > access-list 10 permit 150.50.3.0
> > >
> > > route-map RM_150_50_4_Only permit 10
> > > match interface Loopback2
> > > !
> > > route-map O_IN_B permit 10
> > > match ip address 10
> > > !
> > >
> > >
> > > OSPF Router with ID (200.0.0.8) (Process ID 8)
> > >
> > >
> > > Router Link States (Area 0)
> > >
> > > Link ID ADV Router Age Seq# Checksum
Link
> count
> > > 200.0.0.7 200.0.0.7 243 0x80000019 0xF97C 2
> > > 200.0.0.8 200.0.0.8 242 0x80000019 0x7B1C 3
> > >
> > > Type-5 AS External Link States
> > >
> > > Link ID ADV Router Age Seq# Checksum
Tag
> > > 150.50.4.0 200.0.0.8 247 0x80000001 0xF88A 0
> > >
> > >
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