From: Rsharma (cciers09@gmail.com)
Date: Wed Feb 04 2009 - 14:13:22 ARST
Its true that default behavior is for the check to be ON.
I just played with default behavior and disabled Validation check by command
no validate-update-source .
and routers started exchanging routes .but when i disabled spilt horizon on
incoming interface .router started looking for validation check even though
*no validate-update-source *
command exist .
So this caused me to look for a relation with Split Horizon and
Validation-update-source check .
Cheers!!!
Rsharma :-)
On Tue, Feb 3, 2009 at 6:51 PM, ALL From_NJ <all.from.nj@gmail.com> wrote:
> Well ... the cool thing is that the default behavior is for the check to be
> on. I never saw the split horizon comment until I looked this up, so as I
> understand it, with or without split horizon, this check will happen. Did
> you find different?
>
> I forgot all the 'rules and caveats' with this ... but having secondary
> addressing on a peer neighbor can cause some problems.
>
> If updates are sourced from the secondary address, and this secondary
> address is from another network than the peering router, then you would need
> to use the 'no' keyword in order for rip to accept the updates.
>
>
>
>
> On Tue, Feb 3, 2009 at 12:17 PM, Rsharma <cciers09@gmail.com> wrote:
>
>> Hi ,
>>
>> Just want to knw the reason behind it that Disabling split horizon on the
>> incoming interface cause the system to perform this validation check .
>>
>> I tried this with Dynamip lab and its correct but i wasnt able to
>> co-relate Split Horizon with Validate check .
>>
>> Thanks!!!!!!
>> Rsharma :-)
>>
>> ALL From_NJ wrote:
>>
>>> I am learning to search the docs ... I have a feeling I will need
>>> them!!! ;-)
>>>
>>> Here is a link to this command (watch the ugly word wrap):
>>>
>>> http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_rip.html#wp1012874
>>>
>>> Copied and pasted from the link:
>>>
>>> To have the Cisco IOS software validate the source IP address of incoming
>>> routing updates for Routing Information Protocol (RIP) and Interior Gateway
>>> Routing Protocol (IGRP) routing protocols, use the validate-update-source
>>> command in router configuration mode. To disable this function, use the no
>>> form of this command.
>>>
>>> validate-update-source
>>> no validate-update-source
>>>
>>> ---->>>> Usage Guidelines
>>>
>>> This command is applicable only to RIP and IGRP. The software ensures
>>> that the source IP address of incoming routing updates is on the same IP
>>> network as one of the addresses defined for the receiving interface.
>>>
>>> Disabling split horizon on the incoming interface will also cause the
>>> system to perform this validation check.
>>>
>>> For unnumbered IP interfaces (interfaces configured as IP unnumbered), no
>>> checking is performed.
>>> Examples
>>>
>>> The following example configures a router not to perform validation
>>> checks on the source IP address of incoming RIP updates:
>>>
>>> router rip
>>> network 10.105.0.0
>>> no validate-update-source
>>>
>>> HTH,
>>>
>>>
>>>
>>>
>>> On Mon, Feb 2, 2009 at 1:43 PM, Rsharma <cciers09@gmail.com <mailto:
>>> cciers09@gmail.com>> wrote:
>>>
>>> Hi,
>>>
>>> Validate Update source command in RIPv2 n IGRP .
>>> What exactly is being scanned by protocol to validate ....????
>>>
>>> can anyone zoom on Validate action ??
>>>
>>> Thanks
>>> Rsharma
>>>
>>>
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>>> --
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>>>
>>
>>
>
>
> --
> Andrew Lee Lissitz
> all.from.nj@gmail.com
Blogs and organic groups at http://www.ccie.net
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