From: Ahmed Mustafa (ahmed.mustafa@sbcglobal.net)
Date: Fri Apr 02 2004 - 02:59:28 GMT-3
Bill,
I agree with Packet Man's thought. You are one of the best when comes
to explain difficult subjects in plain english with practical scenerios.
Ahmed
----- Original Message -----
From: "Packet Man" <ccie2b@hotmail.com>
To: <bill@eccie.com>; <gladston@br.ibm.com>; <ccielab@groupstudy.com>
Sent: Thursday, April 01, 2004 2:27 PM
Subject: 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?
> >
> >_______________________________________________________________________
> >Please help support GroupStudy by purchasing your study materials from:
> >http://shop.groupstudy.com
> >
> >Subscription information may be found at:
> >http://www.groupstudy.com/list/CCIELab.html
> >
> >_______________________________________________________________________
> >Please help support GroupStudy by purchasing your study materials from:
> >http://shop.groupstudy.com
> >
> >Subscription information may be found at:
> >http://www.groupstudy.com/list/CCIELab.html
>
> _________________________________________________________________
> Persistent heartburn? Check out Digestive Health & Wellness for
information
> and advice. http://gerd.msn.com/default.asp
>
> _______________________________________________________________________
> Please help support GroupStudy by purchasing your study materials from:
> http://shop.groupstudy.com
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Mon May 03 2004 - 19:48:41 GMT-3