Re: How would you solve this task?

OK, now I see what they were after. So, when you have "auto-summary"
enabled (the default) any routes that the router itself auto summarizes will
have a summary route to null0 locally. Disabling auto-summary does get rid
of these. However, if you have a manually created summary route via "ip
summary-address eigrp" on the interface level, the locally generated summary
to null0 will be there regardless of it you have auto-summary disabled or
not.

That makes more sense now. At the end of the day, I still like your
solution better because the task did not state HOW the summary was put into
the routing table (manually or automatically)

HTH

On Tue, Aug 9, 2011 at 1:11 PM, Joe Astorino <joeastorino1982_at_gmail.com>wrote:

> It seems there is quite a bit of information out there saying if you
> disable auto-summary in EIGRP that the summary routes to null0 go away. To
> double check my sanity I have just labbed this up, and again the common
> belief is not consistent with my test
>
> R2#sh ip int brie | exc unass
> Interface IP-Address OK? Method Status
> Protocol
> FastEthernet0/0 12.12.12.2 YES NVRAM up
> down
> Serial0/1/0.204 24.24.24.2 YES NVRAM up
> up
> Serial0/1/0.205 25.25.25.2 YES NVRAM down
> down
> Loopback0 2.2.2.2 YES NVRAM up
> up
>
> R2#sh run | b router eigrp
> router eigrp 1
> passive-interface default
> no passive-interface Serial0/1/0.204
> network 2.2.2.2 0.0.0.0
> network 24.24.24.2 0.0.0.0
> no auto-summary
>
> interface Serial0/1/0.204 point-to-point
> ip address 24.24.24.2 255.255.255.0
> ip summary-address eigrp 1 2.2.0.0 255.255.0.0 5
> snmp trap link-status
> frame-relay interface-dlci 204
>
> R2#sh ip ro e
> 2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
> D 2.2.0.0/16 is a summary, 00:00:38, Null0
>
>
>
>
>
> On Tue, Aug 9, 2011 at 12:50 PM, Joe Astorino <joeastorino1982_at_gmail.com>wrote:
>
>> Good question. My view with EIGRP is that there is absolutely no reason
>> to NOT disable auto summarization unless you have a really really good
>> reason (i.e. the lab says so). Disabling auto-summary should be a given
>> every time you type "router eigrp". With that being said, I think the
>> solutions guide you have is wrong. Disabling auto-summarization in EIGRP
>> does not disable summary routes to null0, at least in the recent experiments
>> I have done.
>>
>> I think your solution of changing the AD on the summary to 255 is a fine
>> solution and it meets the requirements of the task.
>>
>> Check out this blog:
>> http://astorinonetworks.com/2011/07/20/summary-routes-to-null0-the-protocols-that-love-them/
>>
>>
>>
>>
>> On Tue, Aug 9, 2011 at 12:46 PM, Daniel Dib <daniel.dib_at_reaper.nu> wrote:
>>
>>> On ti, aug 09, 2011 at 17:31:46, Joe Astorino wrote:
>>> > Cc: ccielab_at_groupstudy.com
>>> > Subject: Re: How would you solve this task?
>>> >
>>> > Lots of great advice in this thread, but here is my two cents. I like
>>> > your solution better. It is more specific and in my opinion more
>>> > technically correct. However, that is not the point of my post. The
>>> > point is, this is a task that is a great example of when to clarify
>>> > with the proctor. Make sure you choose your words carefully. I might
>>> > have said something like "This task wants me to log successful and
>>> > unsuccessful telnet attempts. I believe there are multiple ways to
>>> > define a telnet attempt. For example, I could simply log all packets
>>> > destined for the well known telnet port of TCP 23, or I could be very
>>> > specific and log login success/failures using the login feature set.
>>> > Could you clarify which would be more acceptable, or does it matter?"
>>> >
>>> > HTH
>>> >
>>>
>>> Hi Joe,
>>>
>>> Great advice. What would you recommend for the task below:
>>>
>>> 1.10 TROUBLE TICKET 10
>>> R1's routing table has a summary pointing to Null0. Modify R1 so that
>>> there
>>> are no routes to Null0.
>>>
>>> SG solution: Turn off auto-summary under EIGRP.
>>>
>>> My solution: Announce summary with AD of 255 on Ethernet interface which
>>> meant it is not installed locally with the ip summary address eigrp
>>> command.
>>> If the task had said something like make sure that classless routing is
>>> used
>>> or anything like that I would definitely have removed auto-summary. Maybe
>>> it
>>> is a safe assumption that auto-summary should not be used unless a task
>>> tells you to, guess that is one more for the proctor.
>>>
>>> Also one of those tasks that could easily get misinterpreted.
>>>
>>> Once again, thanks for your input.
>>>
>>>
>>> /Daniel
>>>
>>>
>>
>>
>> --
>> Regards,
>>
>> Joe Astorino
>> CCIE #24347
>> Blog: http://astorinonetworks.com
>>
>> "He not busy being born is busy dying" - Dylan
>>
>>
>
>
> --
> Regards,
>
> Joe Astorino
> CCIE #24347
> Blog: http://astorinonetworks.com
>
> "He not busy being born is busy dying" - Dylan
>
>

-- 
Regards,
Joe Astorino
CCIE #24347
Blog: http://astorinonetworks.com
"He not busy being born is busy dying" - Dylan
Blogs and organic groups at http://www.ccie.net