I understand the "Potential" for Routing Loops.
But I also know that in most cases, you can always handle that by "manipulating" the "distance" of each protocol using either the "distance command" or some other method to accomplish this.
I have been told by a couple of guys at IPExpert that "it is just a matter of taste"
For instance, I know that some guys like Scott Morris (when he was with IPExpert), are BIG fan of Route Tags.
I have the Material written by him when he was still there (couple of years ago)
After he left, most of the Mock Labs were solved using "Simple Redistribution" without using Route Tags.
Then I was told that "I was VERY unlikely" to get Route Tag Lab scenarios
in the Real CCIE Lab.
I was told that about a year ago.
I just wonder what other people think about this.
Is it really "a matter of taste"?
I know that if the Lab is written asking specifically to use them, then there will be no way around. But if they don't ask for it .... I guess I don't have to use them!
So the question in other words is: "How likely are they (Cisco Proctors) to specifically request the use of Route Tags" ??
25% ???, 50% ??? 75%???
Thanks!
--- On Fri, 12/10/10, Chris Fata <[email protected]> wrote:
From: Chris Fata
<[email protected]>
Subject: Re: [OSL | CCIE_RS] Route tagging with redistribution
To: "CCIE_RS OnlineStudyList" <[email protected]>
Date: Friday, December 10, 2010, 4:46 PM
Anytime
that you are going to be redistributing a protocol into another and then back
into that originating protocol you are going to have potential for routing
loops.
With that being said.....the exam is designed to test your understanding of the
technology and if I were designing a scenario you can bet I would introduce
potential for loops.
In short....I would understand this technology backward and forward as this is
fair game on the exam.
As for real life applications, I am a systems engineer for a consulting firm
and these scenarios come up quite a bit when you’re talking about redundancy
within the topology.
Think of it this way....even if you do not get redistribution with route
tagging on the exam, it will make you a stronger engineer to fully understand
the technology and disseminate how the router thinks.
My two cents.
Christopher Fata | 616.528.0660 | CCIE Written, CCNP, MCSE |  | www.netechcorp.com
From:
[email protected]
[mailto:[email protected]] On Behalf Of Marko
Milivojevic
Sent: Friday, December 10, 2010 4:28 PM
To: Carlos Valero
Cc: CCIE_RS OnlineStudyList
Subject: Re: [OSL | CCIE_RS] Route tagging with redistribution
Carlos,
You are very likely to find a scenario that is
"best" solved using route tagging in your lab exam.
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
Telephone: +1.810.326.1444
On Fri, Dec 10, 2010 at 12:00, Carlos Valero <[email protected]> wrote:
|
Hello,
I have a general question about Route Tagging.
Although the general idea seems pretty simple,
the actual implementation can be VERY complex and it
usually leads to BIG mess!
How likely are we to find
Route Tagging Lab scenarios in the real CCIE Lab Exam?
I had been told that it is very unlikely that we'll have
to deal with it in the Exam.
Is that true? Should I not pay too much
attention to it and basically "gamble" on the possibility of NOT
finding it in the real Lab Exam?
Does anyone really mess with these Tags in real life?
Or is it a seldom use feature as so many obscure IOS
features?
I hope somebody can shed some light on this.
--- On Mon, 11/2/09, Vikas Sharma <[email protected]>
wrote:
From: Vikas Sharma <[email protected]>
Subject: [OSL | CCIE_RS] Route tagging and redistribution between an IGP and
EGP
To: "CCIE_RS OnlineStudyList" <[email protected]>
Date: Monday, November 2, 2009, 7:13 PM
Hi Guys,
I need your help out here. I have created a lab in GNS as
follows:
R0 - R1 - R2 - R3 all run EIGRP.
R2 - R3 - R4 run BGP as well.
R2 - R3 redistribute EIGRP into BGP and vice versa.
I am attaching a zip file with the drawing plus configs
and the NET file.
The intention of this lab is as follows.
- R0 and R1 simulate 2 client sites
connected together.
- We have a route map on each router that
sets tags on routes that are not local to that particular site.
- This route map is applied to a distribute
list in the direction of routers R2 and R3 respectively.
- I managed to get the EIGRP part working.
- However, as far as tagging routes is
concerned, for some reason R1 has stopped tagging routes to send them
onwards to R3. It worked yesterday and not today and I wonder if this is
a GNS thing.
- On R2 and R3 there is another route map
that looks for tags and then does an as-prepend to make tagged routes
more expensive and send them to R4 which is like a remote site router.
The idea is that BGP must see 2 paths which we influence, in its routing
table and should one of the sites (either R0 or R1) goes off the air it
should automatically be able to use the second path to reach that
network.
- When I apply the redistribute statement
with the route map in BGP on routers R2 and R3, I find that the BGP
routing table has only a few networks learnt and no alternative path.
- I then took off the redistribute eigrp
statement off the BGP config and re-added it in without the route-map
and lo and behold, I see all the routes on R4 and each have an
alternative path. Result is exactly as I want but I want to influence
the routes in BGP. So, basically, if routes originating on R0 and seen
on R2, the routing on R4 for those networks should be via R2 and not R3.
Right now I'm not able to influence these routing decisions.
However, without the route-map, it works beautifully but I
want to use route tagging to influence how BGP decides where to route and
have an alternative path.
I look forward to your feedback.
Cheers,
--
Vikas Sharma
Network Specialist
Fujitsu Australia
(M): 0421 052 117
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