From: Richard Dumoulin (richard.dumoulin@vanco.es)
Date: Fri Apr 02 2004 - 04:56:35 GMT-3
Best is that thanks to his writing style, complex themes are very well
explained with simple words. I know this because I am a non native english
speaker but I understand everything Bill explains.
Thank you,
--Richard
-----Mensaje original-----
De: Packet Man [mailto:ccie2b@hotmail.com]
Enviado el: viernes, 02 de abril de 2004 0:28
Para: bill@eccie.com; gladston@br.ibm.com; ccielab@groupstudy.com
Asunto: RE: BGP and OSPF RID [bcc][faked-from][bayes]
Bill,
You have some of the best written and most informative and insightful posts
I've seen here on GS. I always learn something new whenever I read your
posts even when it's on a topic I'm very knowledgable about. So, I hope
you'll keep sending in your thoughts.
thanks, pm
>From: Bill Lijewski <bill@eccie.com>
>Reply-To: Bill Lijewski <bill@eccie.com>
>To: gladston@br.ibm.com, ccielab@groupstudy.com
>Subject: RE: BGP and OSPF RID [bcc][faked-from][bayes]
>Date: Thu, 1 Apr 2004 13:44:57 -0800
>
>Synchronization only comes into play for iBGP routes. With
>synchronization on the router will check its IGP table for all iBGP
>routes it learns to make sure that it has a matching entry before it
>will ever put the route into its BGP table as a best route.
>Synchronization does not check for a match in the IGP table for eBGP
>routes. If no match is found in the IGP table for the iBGP routes they
>will not be marked as best, and the routes will not be passed to any
>other BGP neighbors.
>
>There is one extra step that BGP goes through for iBGP routes when
>synchronization is on and OSPF is the underlying IGP. BGP will check
>for a matching route in the IGP table, if one is found it will check to
>see which IGP protocol is running. If the router is running OSPF as its
>IGP, BGP will check and make sure that the origin of the routes for both
>OSPF and BGP are the same. In other words BGP will make sure that the
>OSPF and BGP router IDs of the source of the route match before it will
>put it into the BGP table.
>
>You can check these Router ID origins with the following two commands:
>
>For the OSPF route: show ip route x.x.x.x
>
>For an example we can see what the origin of the 210.10.10.0/24 network:
>
>Routing entry for 210.10.10.0/24
> Known via "ospf 1", distance 110, metric 1, type extern 2, forward
>metric 10
> Last update from 172.168.1.2 on Ethernet0, 1d03h ago
> Routing Descriptor Blocks:
> * 172.168.1.2, from 5.5.5.5, 1d03h ago, via Ethernet0
> Route metric is 1, traffic share count is 1
>
>The second line up from the bottom is the important one. It shows 'from
>5.5.5.5', 5.5.5.5 is the OSPF origin ID for this route.
>
>
>For the BGP route: show ip bgp x.x.x.x
>
>Again we can take a look at the origin of the 210.10.10.0/24 network:
>
>BGP routing table entry for 210.10.10.0/24, version 2
>Paths: (1 available, best #1, table Default-IP-Routing-Table)
> Advertised to non peer-group peers:
> 192.168.2.2
> Local
> 172.168.1.2 from 5.5.5.5
>Origin IGP, metric 0, localpref 100, valid, internal, synchronized,
>best
>
>Again the second line up from the bottom shows 'from 5.5.5.5', 5.5.5.5
>is the BGP origin ID for this route.
>
>In this case both the BGP and the OSPF origin Router ID's match so this
>route could be placed into the BGP table as a best route.
>
>
>- Bill Lijewski
>CCIE#8642
>Network Learning Inc
>5 Day R&S CCIE Bootcamp Instructor
>http://www.ccbootcamp.com
>bill@eccie.com
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>gladston@br.ibm.com
>Sent: Thursday, April 01, 2004 1:25 PM
>To: ccielab@groupstudy.com
>Subject: BGP and OSPF RID [bcc][faked-from][bayes]
>Importance: Low
>
>I remember to see a problem related to OSPF and BGP RID, redistribution
>and Route Refletor.
>
>Any help on where it is on the DOCCD or cisco.com?
>
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