From: Wang, Ting \(Taylor\) (wangting@avaya.com)
Date: Thu May 04 2006 - 10:50:16 ART
Hi Godswill,
Thanks for you instruction. Come back to this question. The solution in
the Lab 15 has the same idea on filtering as your sample, but there is
mistake indeed. I agree on your configure, but still think the distance
will be needed for some scenario.
Taylor
-----Original Message-----
From: Godswill Oletu [mailto:oletu@inbox.lv]
Sent: Thursday, May 04, 2006 7:48 PM
To: Wang, Ting (Taylor); ccielab@groupstudy.com
Subject: Re: IEWB Lab 3 task 5.24 and Lab 15 task 5.28 Dual ponit
redistibution between eigrp and OSPF
Wang,
Redistributing with a route-map and tagging (route coloring), then
denying those routes back into the IGP where they came from might be a
better approach.
Further, you can then use Distance, to decide which of the various IGPs
on a particular router will be brought into the routing table and which
will be acting as a backup route.
For EIGRP visa-vi OSPF, I normally use something like:
route-map EIGRP_TO_OSPF deny 10
match tag 110
!
route-map EIGRP_TO_OSPF permit 1000
set tag 90
!
route-map OSPF_TO_EIGRP deny 10
match tag 90
!
route-map OSPF_TO_EIGRP permit 1000
set tag 110
!
As for some of these CCIE workbooks, there are tones of errors and a few
occassions flat out misrepresentation. You have to work yourself through
them. I also found numerous occassion, where the Workbook, will restrict
you from using a particular method or command and sincerely there is no
other method to meet that requirement. Sometimes, I struggle for hours
to see if there is another command.
Usually at the last minute, I will give and look at the solution and I
will be SHOCKED and ANNOYED to find out that solution guide used that
very method they told you not to use.
A few examples are:
*A scenario stated stated that let R4&R5 authenticate each other, one
use PAP and the other use CHAP, but do not use the 'USERNAME' command on
R4.
>surprising, the solution guide bent so low to use the username command
>on
R4.
*Another scenario states something like, to prevent R2 in a multi-access
ethernet broadcast medium from telneting to the R3, but all FILTERING
MUST BE DONE ONLY ON R6 which is also sharing that same common
multi-access ethernet broadcast subnet. All three Routers share the same
IP subnet and are on the same cable segment, the same VLAN.
>The solution guide solution, went and configure 'switchport protected'
>on
SW1; enabled access list & proxy arp on R6. -why configure SW1 at all?
Switchport protected filter traffics, it prevents traffics from a port
having that feature configured from accepting traffic from another
protected port.
*I have seen solution guides using static routes to maneuver their way
out of a restriction, they created themselves. But their general
instruction said "DO NOT USE STATIC ROUTES, UNLESS SPECIFICALLY ASKED TO
DO SO IN A SECTION' and no where in the task was static route permitted.
I can go on and on. Not to mention solutions that are flat right wrong
and others that will hang your router when you implement them.
It is totally demoralizing to a student who really want to learn and in
keeping with best known practices only want to consult the solution
guide at the 11th hours to spend mental manpower, resources, hours, etc
to work around restrictions, only to open the solution guide and those
same rules of the game are being violated.
Some of these workbook just want to win in the "Our Labs are Tough"
contest, and sincerely that is all they are able to achieve, Some of the
scenarios and their solutions do not help one and they are completely
out of touch and out out sink.
Use them just as a guide, again that is why just reading through the
solution guide without actually labbing up the scenario is a recipe for
disaster.
HTH
Godswill Oletu
----- Original Message -----
From: "Wang, Ting (Taylor)" <wangting@avaya.com>
To: <ccielab@groupstudy.com>
Sent: Thursday, May 04, 2006 3:14 AM
Subject: IEWB Lab 3 task 5.24 and Lab 15 task 5.28 Dual ponit
redistibution between eigrp and OSPF
> Hi Group,
>
> I found some interesting stuff during practicing the dual point
> redistribution between eigrp and OSPF.
> The solution for the dual redistribution between eigrp and OSPF Lab 3
> is as following, but I find it can't solve all the problem of route
> loop.
>
> R1 & R2
> router ospf 1
> redistribute eigrp 100 subnets route-map EIGRP2OSPF
> distance ospf external 171
>
> In case there is external route redistributed from other routing
> protocol for both OSPF and EIGRP domain, the problem will appear. To
> change the distance of OSPF external higher than EIGRP EX will prevent
> the EIGRP EX route redistribute back to
> EIGRP domain, but two result will happen for the external Route in
OSPF
> domain.
>
> 1) One of the R1 and R2 will select the sub-optimal route, via EIGRP
> instead of OSPF to these OSPF external route.
> 2) These route will be redistributed back to OSPF domain, even it is
> only in the OSPF database.
>
> The solution in Lab 15 only do filter for OSPF to EIGRP and EIGRP to
> OSPF to prevent route loop, but I 'm thinking the solution also have
> some limitation. The EIGRP EX routes will be override by OSPF in one
of
> the OSPF ASBR, because OSPF external distance win. That may also
cause
> the sub-optimal route.
> The summary:
> 1) The solution in Lab3 solve the route loop of the EIGRP external
> route, but the route loop may happen on ospf type 5 route. The
> sub-optimal route may happen.
> 2) The solution in Lab 15 will cause the sub-optimal route for EIGRP
EX
> route. Route loop may still happen if the filter on apply on one ASBR.
> My idea is to combine the solution of Lab 3 and Lab 15.
> Anyone have some idea on that?
> Thanks,
> Taylor
>
>
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