From: Scott Morris (swm@emanon.com)
Date: Mon Jan 29 2007 - 16:48:11 ART
As opposed to their being a "best way" (which there rarely is anything that
fits all circumstances), the best thing you can do is sit and plan,
configure and watch what occurs at each point.
A good way with this involves both TCL script for pinging (every IP address
of your network should be listed) and debugs...
Before doing any redistribution it is simple to predict what things you can
or cannot ping from any one location. Before doing any redistribution,
enable "debug ip routing". Assuming you have stable protocols to begin
with, when you do your first redistribution, you should see a predictable
influx of routes and be able to know what things can or cannot be pinged
from any location. (gaps here may answer your redistribute connected
question)
As you add more and more redistribution points, each time, repeat the
process. Again, you'll be able to watch the routes move (from the debug)
and test things with pings to make sure what you are getting lines up with
what you thought should be happening.
This process, while very tedious, is the best way to get a true grasp about
what your router is (or is not) thinking during the redistribution
processes. The ability to think it through and predict what will happen
will help you figure out what will happen in any situation that you happen
to run across. Also, using route tags may be a more efficient way of
allowing/not allowing routes in different places.
HTH,
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, JNCIE
#153, CISSP, et al.
CCSI/JNCI-M/JNCI-J
IPexpert VP - Curriculum Development
IPexpert Sr. Technical Instructor
smorris@ipexpert.com
http://www.ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Filyurin, Yan
Sent: Monday, January 29, 2007 2:03 PM
To: ccielab@groupstudy.com
Subject: Multiple route redistribution points
Hello Group Study. I have a possible set of questions regarding route
redistribution. Let's say I have 4 routers A, B, C and D, all
interconnected and running the same routing protocol. For example OSPF.
Routers A and B connect to the same RIP domain and routers C and D connect
to say EIGRP domain. Mutual redistribution needs to be done between all IGP
protocols.
The first task that needs to be done is that since there are multiple
redistribution points, all I have to do is through the use of route tags
control so that routes from one routing protocol don't redistributed back
into it. That is pretty straightforward.
What becomes interesting is when it is a good idea to use distance command.
For example if routers A and B are acting as redistribution points into RIP
and RIP has higher distance than OSPF, then router B or router A will have
RIP routes from RIP domain and OSPF E1 or E2 routes that got redistributed.
So it would see logical to set distance of RIP to be 109 for example. And
if I do that suddenly OSPF routes from C and D not to mention routes that
came from EIGRP domain have a similar problem. On A an B they become
preferred through RIP. Similar problems could exist with EIGRP, but at
least with EIGRP it is easier since it does differentiate between external
and internal
Since RIPv2 does not distinguish between internal and external routes, I
guess I could do something, assuming I can't summarize and need complete
redundancy. I can set distance command to selectively choose which routes
get what distance and from what sources, but that takes access lists and I
have to do it both redistribution point routers. Is there anything else I
can do to make the whole thing easier and does any of this sound right?
Also is it always a good idea when doing mutual redistribution to
redistribute connected routes into all IGP protocols, that haven't been
redistributed previously or were not part of the network statement?
Yan
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