From: Howard C. Berkowitz (hcb@xxxxxxxxxxxx)
Date: Sun Apr 07 2002 - 21:23:39 GMT-3
I've been working on a practice scenario, involving, among many other
things, RIP-OSPF mutual redistribution. My challenge is that I wanted
to do something that is real-world good practice: standardizing on
loop0 interface addresses that are /32, postulating the customer
would eventually transition completely to OSPF.
The challenge is how to ping discontiguous /32's in a RIP network. In
principle, it's not something RIPv1 can do. If this were the real
world, I could solve this trivially with a couple of static and
default routes. I can make it work under some fairly bizarre
constraints, like using extended ping to force a source address to
which has a return path.
To do what I want to do with routing, however, the alternatives are
so bizarre that I wonder if it's beyond what conceivably could be on
the test. Now, this is NOT a request for NDA information, but it's
my impression from Solie and various CCIE power sessions that the lab
scenarios NEVER use static or default routes. Am I correct here, or
is "NEVER" really "HARDLY EVER"?
Let's see...some of the ways I've hacked it:
1. Implement policy routing and set default interface.
2. Use BGP as an intermediate protocol between RIP and OSPF so I
can use conditional default advertisement
OSPF default-information originate doesn't fit the bill, because I
have two redistribution points. If I had one redistribution point, I
could, in good conscience, do default-information originate always,
because the traffic would blackhole. But with two points of
redistribution, I want default originated only if the point of
redistribution indeed can act as a default router.
BGP conditional advertisement would do what I want. If I could put a
default route into the OSPF router, and control default origination
by the reachability of the next hop of the default route, I could
also make it work. The OSPF router really wouldn't use the default
route other than as a control mechanism for default information
originate.
Am I simply creating a situation that is outside the reasonable scope
of the lab?
This scenario and others, incidentally, will be available for free
noncommercial use from Gettlabs, but we need to work out some server
issues that I hope will be done in the next couple of days. It's too
long to post here.
-- "What Problem are you trying to solve?" ***send Cisco questions to the list, so all can benefit -- not directly to me*** ******************************************************************************* * Howard C. Berkowitz hcb@gettcomm.com Chief Technology Officer, GettLab/Gett Communications http://www.gettlabs.com Technical Director, CertificationZone.com http://www.certificationzone.com "retired" Certified Cisco Systems Instructor (CID) #93005
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:59 GMT-3