From: CCIE GOAL (ccie.goal@gmail.com)
Date: Wed Jun 06 2007 - 14:39:21 ART
No, I am not using confederations... it is a simple scenario
Follow the "show ip bgp" outputs.
AS1#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
*> 10.10.0.0/24 2.2.2.2 0 2 3 i
*> 10.10.1.0/24 2.2.2.2 0 2 3 i
*> 10.10.2.0/24 2.2.2.2 0 2 3 i
*> 10.10.3.0/24 2.2.2.2 0 2 3 i
*> 10.10.4.0/24 2.2.2.2 0 2 3 i
*> 10.10.5.0/24 2.2.2.2 0 2 3 i
*> 10.10.6.0/24 2.2.2.2 0 2 3 i
AS1#
-----------------------------------------------------------------
AS2 (Router1)#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
*> 10.10.0.0/24 3.3.3.3 0 0 3 i
*> 10.10.1.0/24 3.3.3.3 0 0 3 i
*> 10.10.2.0/24 3.3.3.3 0 0 3 i
*> 10.10.3.0/24 3.3.3.3 0 0 3 i
*> 10.10.4.0/24 3.3.3.3 0 0 3 i
*> 10.10.5.0/24 3.3.3.3 0 0 3 i
*> 10.10.6.0/24 3.3.3.3 0 0 3 i
AS2#
-----------------------------------------------------------------
AS2 (Router2)#sh ip bgp | b Net
Network Next Hop Metric LocPrf Weight Path
*> 10.10.0.0/24 3.3.3.3 0 0 3 i
*> 10.10.1.0/24 3.3.3.3 0 0 3 i
*> 10.10.2.0/24 3.3.3.3 0 0 3 i
*> 10.10.3.0/24 3.3.3.3 0 0 3 i
*> 10.10.4.0/24 3.3.3.3 0 0 3 i
*> 10.10.5.0/24 3.3.3.3 0 0 3 i
*> 10.10.6.0/24 3.3.3.3 0 0 3 i
AS2#
-----------------------------------------------------------------
AS3#sh ip bgp vpnv4 vrf AS3 | b Net
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 2:1 (default for vrf AS3)
*> 10.10.0.0/24 0.0.0.0 0 32768 i
*> 10.10.1.0/24 0.0.0.0 0 32768 i
*> 10.10.2.0/24 0.0.0.0 0 32768 i
*> 10.10.3.0/24 0.0.0.0 0 32768 i
*> 10.10.4.0/24 0.0.0.0 0 32768 i
*> 10.10.5.0/24 0.0.0.0 0 32768 i
*> 10.10.6.0/24 0.0.0.0 0 32768 i
AS3#
-----------------------------------------------------------------
Regards,
Luciano
2007/6/6, Marko Milivojevic <markom@vodafone.is>:
>
>
> Redistribute-internal was my initial gut response to this problem, but
> then I decided to write up the solution that is not using it. Are you using
> BGP confederations? Can you send us "sh ip bgp" output from all BGP
> speakers?
>
>
> ________________________________
>
> From: CCIE GOAL [mailto:ccie.goal@gmail.com]
> Sent: 6. jznm 2007 16:48
> To: Marko Milivojevic
> Cc: Cisco certification
> Subject: Re: eBGP redistribution
>
>
> Hey Marko, many thanks for the reply!
>
> Nice check list you have done, and I am conforming with it...
> Follow the anwers, and bellow is the Problem and Solution... now I am
> looking for the reason...
>
>
>
-----------------------------------------------------------------------------
-------------------------
> 1- AS2 and AS3 need to have directly connected peering
> - Otherwise you need to redistribute that routing protocol into AS2 OSPF
>
> A: Ok, they are directly connected.
>
> 2- AS2-AS3 border router in AS2 needs to redistribute prefixes learned
> from AS3 BGP into OSPF
>
> A: Ok, there is redistribution from BGP 2 into OSPF
>
> 3- AS1-AS2 need to have multihop eBGP peering
>
> A: Ok, It is configured...
>
> 4- AS2 OSPF router connected to AS1 needs to inject AS1 prefixes into OSPF
> - it may also filter routes propagating to AS2, as those routes would be
> learned in AS1 via BGP
> - it must not filter out AS2 BGP's peering address!
>
> A: Actually the OSPF is announcing a default-route to AS1 OSPF
> domain...
>
>
-----------------------------------------------------------------------------
-------------------------
>
>
> The Problem:
> The AS2 was receiving the prefixes from AS3 and then, for some reason, the
> AS2 is treating the AS3 prefixes as internal and not external...
>
> When I tried to redistribute the BGP 2 into OSPF the AS3 prefixes could
> not be sent as they are treated as internal...
>
> The Solution:
> To solve this problem I had to add the "bgp redistribute-internal"...
>
> The "Why?":
> Why the AS3 prefixes is treated as internal in AS2?
> If someone knows, can please explain me that?
>
> Best Regards,
> Luciano
>
>
>
>
> 2007/6/6, Marko Milivojevic <markom@vodafone.is>:
>
>
> As usual, I may be wrong, but with the information provided, I
> think the text below will summarize what needs to be done to make this
work.
>
> You will need to make sure few things:
>
> 1- AS2 and AS3 need to have directly connected peering
> - Otherwise you need to redistribute that routing protocol into AS2
> OSPF
> 2- AS2-AS3 border router in AS2 needs to redistribute prefixes
> learned from AS3 BGP into OSPF
> 3- AS1-AS2 need to have multihop eBGP peering
> 4- AS2 OSPF router connected to AS1 needs to inject AS1 prefixes
> into OSPF
> - it may also filter routes propagating to AS2, as those routes
> would be learned in AS1 via BGP
> - it must not filter out AS2 BGP's peering address!
>
> Alternative approach to this problem is to use MPLS in AS2, but
> then again, I'm preparing for SP lab and that may cloud my judgement here
> :-)
>
> There may be other alternatives, but to present them, we may need
> better description of the problem, as well as "sh ip bgp" outputs from all
> involved routers, to begin with.
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf Of CCIE GOAL
> Sent: 6. jznm 2007 15:42
> To: ccielab@groupstudy.com
> Subject: eBGP redistribution
>
> Hi guys,
>
> I ran into a problem with BGP, maybe it's simple to resolve but I
> got stuck
> on it.
> People say that sometimes it is easier to spot the issue from
> outside the
> picture...
>
> Scenario:
>
> [ BGP AS 1 ] -- (OSPF/not in bgp) -- [ BGP AS 2 ] -- [ BGP AS
> 3 ]
>
> - AS 1 is peering to AS 2
> - AS 2 is peering to AS 3
>
> - Between AS 1 and AS 2; there is some devices in OSPF domain only
> (Not
> BGP).
>
> - AS 3 is announcing some prefixes, let's say 10.10.X.0/24...
>
> These prefixes are pingable from AS 2 but not from AS 3 even the
> BGP table
> from AS 3 has these prefix as valid.
>
> The issue is that the OSPF domain do not know how to reach the
> prefixes
> 10.10.X.0/24.
>
> I am not allowed to use static routes anywhere...
> I have tried to redistribute BGP 2 into OSPF but no success, it
> seems that
> eBGP learned prefixes are not redistributed...
>
> Can somebody help me on this?
>
> Follow the configs:
>
>
> ---------------------------------------------------
> AS1#
> router bgp 1
> no synchronization
> neighbor 2.2.2.2 remote-as 2
> no auto-summary
> !
> router ospf 1
> network 10.10.1.1 0.0.0.0 area 1
>
> ---------------------------------------------------
> OSPF#
> router ospf 1
> network 10.10.1.2 0.0.0.0 area 1
> network 10.10.2.2 0.0.0.0 area 0
>
> ---------------------------------------------------
> AS2#
> router bgp 2
> no synchronization
> neighbor 1.1.1.1 remote-as 1
> neighbor 3.3.3.3 remote-as 3
> no auto-summary
> !
> router ospf 1
> network 10.10.2.1 0.0.0.0 area 0
> ---------------------------------------------------
>
> AS3#
> router bgp 3
> no synchronization
> neighbor 2.2.2.2 remote-as 2
> no auto-summary
> ---------------------------------------------------
>
>
> Thanks in advance,
> Luciano
>
>
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