Karl,

I have compiled an article on BGP and BGP synchronization and it is
posted on my website. http://www.networkking.net 
I believe it is the easiest way BGP and BGP synchronization can be
explained.

HTH

Bernard
 
  
 

> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf
Of
> Karl Brusen
> Sent: Tuesday, September 10, 2002 6:16 AM
> To: [EMAIL PROTECTED]
> Subject: BGP/OSPF Synchronization [7:52980]
> 
> Can anyone point me towards a resource that describes in detail what
it
> takes for BGP to consider a route synchronized when it learned it
through
> IGP OSPF?  My study partner and I are struggling understanding how it
> works.
> All of our resources provide only general information with statements
> like,
> "a route must be learned by IGP before BGP will consider it
synchronized".
> Merely learning a route from IGP is apparently not good enough.  There
> must
> be other, more specific requirements.  How does route-reflection
affect
> BGP/OSPF synchronization?
> 
> Specifically, we are working on a lab with three routers running BGP.
> They
> are in the same AS (IBGP).  They are not fully meshed one is acting as
a
> router reflector for the other two.  One of the RR clients has a
loopback
> injected into BGP by redistribute connected.  All three routers are
also
> running OSPF and have an IGP route to the same network being injected
into
> BGP.  The route is synchronized on the router it is injected into and
on
> the
> route reflector, but it isn't synchronized on the other route
reflector
> client.  We are aware of how BGP and OSPF router IDs can prevent
> synchronization, so we have specified the same router IDs for BGP and
> OSPF.
> 
> What is interesting is that if we point a static route from the
problem
> route-reflector client to the BGP route "next hop", BGP synchs.  Due
to
> the
> network topology and modifications of the ad distance, the problem
router
> also has a route learned from EIGRP but is not normally in the IP
routing
> table.  When we shut down an interface so that the EIGRP route is
placed
> in
> the IP routing table, BGP synchs.
> 
> We are very confused.  There is something about how BGP synchs with
OSPF
> that we just don't understand.  Any insight from the group will be
greatly
> appreciated.
> 
> Thanks,
> 
> 
> Karl Brusen




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