From: Raghav Bhargava (raghavbhargava12@gmail.com)
Date: Sun Mar 29 2009 - 19:14:03 ART
yup thanks guys..will do it
thanks all
raghav
On Sun, Mar 29, 2009 at 3:12 PM, Divin Mathew John <divinjohn@gmail.com>wrote:
> yeah lab it up.... read up on the 2 URLs i send you.! Hope that makes it
> easy.!
> Thanking You
>
> Yours Sincerely
>
> Divin Mathew John
> divinjohn@gmail.com
> divin@dide3d.com
> +91 9945430983
> +91 9846697191
> +974 5008916
> PGP PUBLIC KEY BLOCK @ http://www.dide3d.com/divin_Public_PGP_key.txt
> Sent from: Bangalore KA India.
>
> On Mon, Mar 30, 2009 at 3:41 AM, Salah ElShekeil <
> salah.elshekeil@gmail.com> wrote:
>
>> you have to lab it up Raghav you will understand,
>>
>> if you have questions just ping :)
>>
>>
>>
>>
>> On Mon, Mar 30, 2009 at 1:09 AM, Divin Mathew John <divinjohn@gmail.com>wrote:
>>
>>> yeah. salah just put it Small and Simple!
>>> Thanking You
>>>
>>> Yours Sincerely
>>>
>>> Divin Mathew John
>>> divinjohn@gmail.com
>>> divin@dide3d.com
>>> +91 9945430983
>>> +91 9846697191
>>> +974 5008916
>>> PGP PUBLIC KEY BLOCK @ http://www.dide3d.com/divin_Public_PGP_key.txt
>>> Sent from: Bangalore KA India.
>>>
>>> On Mon, Mar 30, 2009 at 3:37 AM, Salah ElShekeil <
>>> salah.elshekeil@gmail.com> wrote:
>>>
>>>> if the router who is generating the summary have no longer match in its
>>>> routing domain then it will discard it
>>>>
>>>>
>>>> On Mon, Mar 30, 2009 at 1:03 AM, Raghav Bhargava <
>>>> raghavbhargava12@gmail.com> wrote:
>>>>
>>>>> Hi divin/salah,
>>>>>
>>>>> Can you guys please answer my questions that I requested for in my
>>>>> mail..I understand in EIGRP wen we create a summary address it creates a
>>>>> Null 0 route but my question is if a packet comes in for a different network
>>>>> what happens then..
>>>>>
>>>>> raghav
>>>>>
>>>>>
>>>>> On Sun, Mar 29, 2009 at 3:00 PM, Salah ElShekeil <
>>>>> salah.elshekeil@gmail.com> wrote:
>>>>>
>>>>>> yep in rip it won't creat route to Null you have to do it manually
>>>>>>
>>>>>> ip route xxxx xxxx null0
>>>>>>
>>>>>> On Mon, Mar 30, 2009 at 12:56 AM, Divin Mathew John <
>>>>>> divinjohn@gmail.com> wrote:
>>>>>>
>>>>>>> and i do think its only in OSPF and EIGRP when u do summarize routes
>>>>>>> internal or external that creates a NULL route automatically.! for
>>>>>>> rip i
>>>>>>> guess will have to create a static route pointing to the Null0 with a
>>>>>>> higher
>>>>>>> administrative distance than any other routing protocol....to avoid
>>>>>>> loops/!
>>>>>>> Thanking You
>>>>>>>
>>>>>>> Yours Sincerely
>>>>>>>
>>>>>>> Divin Mathew John
>>>>>>> divinjohn@gmail.com
>>>>>>> divin@dide3d.com
>>>>>>> +91 9945430983
>>>>>>> +91 9846697191
>>>>>>> +974 5008916
>>>>>>> PGP PUBLIC KEY BLOCK @
>>>>>>> http://www.dide3d.com/divin_Public_PGP_key.txt
>>>>>>> Sent from: Bangalore KA India.
>>>>>>>
>>>>>>> On Mon, Mar 30, 2009 at 3:25 AM, Divin Mathew John <
>>>>>>> divinjohn@gmail.com>wrote:
>>>>>>>
>>>>>>> > The Null interface is typically used for preventing routing loops.
>>>>>>> Enhanced
>>>>>>> >> Interior Gateway Routing Protocol (EIGRP), for instance, always
>>>>>>> creates a
>>>>>>> >> route to the Null0 interface when it summarizes a group of routes.
>>>>>>> Whenever
>>>>>>> >> a routing protocol summarizes, this means that the router might
>>>>>>> receive
>>>>>>> >> traffic for any IP address within that summary. Because not all IP
>>>>>>> addresses
>>>>>>> >> are always in use, there is a risk of looping packets in case
>>>>>>> default routes
>>>>>>> >> are used on the router which receives the traffic for the summary.
>>>>>>> >
>>>>>>> >
>>>>>>> >
>>>>>>> http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a00801c9a6e.shtml
>>>>>>> > refer that doc. u will know why null0 is created
>>>>>>> > and
>>>>>>> >
>>>>>>> >
>>>>>>> http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a00801c9a6e.shtml
>>>>>>> >
>>>>>>> > However, in IOS levels 12.1(6) and higher, this discard route is
>>>>>>> generated
>>>>>>> > by default, and you don't need to create it. If you want to disable
>>>>>>> creation
>>>>>>> > of the discard route, use the *no discard-route* command:
>>>>>>> >
>>>>>>> >> Router1(config)#*router ospf 55*
>>>>>>> >> Router1(config-router)#*no discard-route internal*
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> Router1(config-router)#*no discard-route external*
>>>>>>> >>
>>>>>>> >> With the *internal* keyword, this command prevents the router from
>>>>>>> > automatically generating discard routes for internal summary
>>>>>>> routes.
>>>>>>> > Similarly, the *external *keyword is for external routes. However,
>>>>>>> we urge
>>>>>>> > caution with this command because the absence of a discard route
>>>>>>> can cause
>>>>>>> > loops.
>>>>>>> >
>>>>>>> >
>>>>>>> >
>>>>>>> > Thanking You
>>>>>>> >
>>>>>>> > Yours Sincerely
>>>>>>> >
>>>>>>> > Divin Mathew John
>>>>>>> > divinjohn@gmail.com
>>>>>>> > divin@dide3d.com
>>>>>>> > +91 9945430983
>>>>>>> > +91 9846697191
>>>>>>> > +974 5008916
>>>>>>> > PGP PUBLIC KEY BLOCK @
>>>>>>> http://www.dide3d.com/divin_Public_PGP_key.txt
>>>>>>> >
>>>>>>> >
>>>>>>> >
>>>>>>> > On Mon, Mar 30, 2009 at 2:27 AM, Raghav Bhargava <
>>>>>>> > raghavbhargava12@gmail.com> wrote:
>>>>>>> >
>>>>>>> >> Hi Experts,
>>>>>>> >>
>>>>>>> >> Have some doubts related to Null 0.
>>>>>>> >>
>>>>>>> >> In EIGRP,
>>>>>>> >>
>>>>>>> >> For example if we have 4 networks:-
>>>>>>> >>
>>>>>>> >> 1.1.0.1/24 , 1.1.1.1/24, 1.1.2.1/24, 1.1.3.1/24
>>>>>>> >>
>>>>>>> >> Now lets say I summarise them all under 1 default route by the
>>>>>>> command ip
>>>>>>> >> summary -address eigrp 10 0.0.0.0 0.0.0.0
>>>>>>> >>
>>>>>>> >> when I do this it creates a Null 0 route in the Routing table. So
>>>>>>> If I
>>>>>>> >> would
>>>>>>> >> have not summarise these networks as a default route and would
>>>>>>> have done
>>>>>>> >> it
>>>>>>> >> like this ip summary-address eigrp 10 1.1.0.0 0.0.3.255 .Then will
>>>>>>> the
>>>>>>> >> Null
>>>>>>> >> 0 route be created.???? I don know..
>>>>>>> >>
>>>>>>> >> As per my understanding of Null 0 , it helps in preventing
>>>>>>> forwarding
>>>>>>> >> Loops
>>>>>>> >> . So does it mean that if i want to reach a network which is
>>>>>>> outside of
>>>>>>> >> these 4 networks for eg - 4.4.4.4/24. The Null 0 will drop the
>>>>>>> route for
>>>>>>> >> this network. Please correct me if I am wrong.
>>>>>>> >>
>>>>>>> >> Secondly like in OSPF also when we do summarisation of internal
>>>>>>> /external
>>>>>>> >> routes a null 0 route is created. I know it is used for preventing
>>>>>>> >> forwarding loops but will it do the same thing . I mean if a route
>>>>>>> for a
>>>>>>> >> different network comes in will it drop it.
>>>>>>> >>
>>>>>>> >> Also in OSPF we can remove this Null 0 via the command---> no
>>>>>>> >> discard-route
>>>>>>> >> internal/external. Why do we do that if Null 0 helps in preventing
>>>>>>> the
>>>>>>> >> loops.
>>>>>>> >>
>>>>>>> >> Last but not the least is there a command to do the same in other
>>>>>>> >> protocols
>>>>>>> >> like RIP, EIGRP, BGP.
>>>>>>> >>
>>>>>>> >> just curiosu to know ....
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> --
>>>>>>> >> Warm Regards
>>>>>>> >> Raghav
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> Blogs and organic groups at http://www.ccie.net
>>>>>>> >>
>>>>>>> >>
>>>>>>> _______________________________________________________________________
>>>>>>> >> Subscription information may be found at:
>>>>>>> >> http://www.groupstudy.com/list/CCIELab.html
>>>>>>>
>>>>>>>
>>>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________________________________
>>>>>>> Subscription information may be found at:
>>>>>>> http://www.groupstudy.com/list/CCIELab.html
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Warm Regards
>>>>> Raghav
>>>>>
>>>>
>>>>
>>>
>>
>
-- Warm Regards RaghavBlogs and organic groups at http://www.ccie.net
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