Re: RIP V1 VLSM

Actually that command will disable validating the update source IP
address. Not the mask.

If you have a router which is "off" the network, its update is ignored
until you type "no validate-update-source".

Another thing:
Suppose you are running a RIPv1 and you have different masks on a
link. If you receive an update with "host bits" set, it is recognized
to be a host route then:

R1:fa0/0 --- R2:fa0/0

where

R1:fa0/0 - 10.20.20.1/24
R1:fa0/1 - 10.10.10.1/24

R2:fa0/0 - 10.20.20.2/16
R2:fa0/1 - 10.30.30.2/16

Then you will see the following routes on R1 and R2:

R1 will have a 10.30.0.0/24
R2 will have a 10.10.10.1/32

Lab it, its funny :-))

S pozdravom / Regards,
Miroslav Kosut

On 17.2.2010, at 16:39, Ruhann <groupstudy_at_ru.co.za> wrote:

> The validation done by RIP when a source interface and destination
> interface are using different masks can be disabled with
>
> # router rip
> # no validate-update source
>
> That will work if R1 and R2 has different masks. Not sure though what
> the impact would be with the loopback being whatever.
>
> --
> <ruhann>
> ww.routing-bits.com
>
> On Tue, Feb 16, 2010 at 10:17 PM, miroslav.kosut
> <miroslav.kosut_at_gmail.com> wrote:
>> Oh I had a small typo. The update received on /24 is SENT only via /
>> 24
>> interface.
>>
>> It behaves the same way as if you were running two separate RIP
>> instances in
>> separate VRFs. One VRF includes /16 interfaces and the other one
>> includes
>> /24 only.
>>
>> S pozdravom / Regards,
>> Miroslav Kosut
>>
>> On 16.2.2010, at 19:17, Miroslav Kosut <miroslav.kosut_at_gmail.com>
>> wrote:
>>
>>> Hello,
>>>
>>> I used to lab one scenario with RIPv1 having four interfaces. All
>>> belonging to the same classful network of 10.0.0.0/8. Two of them
>>> were
>>> having the mask /16 and the other ones were having /24.
>>>
>>> Now the interesting part:
>>>
>>> The update I received on /16 interface was sent only through the
>>> other /16
>>> interface AND NOT VIA /24 INTERFACES.
>>> The same is true for /24 interfaces. The update I received on /24
>>> interface I didn't send out the other /24 interface.
>>>
>>> At least subnets of 10.0.0.0/8 have not been forwarded to both /16
>>> and /24
>>> interfaces. I am not sure about different classful networks now..
>>> I forgot
>>> this part, it was even years ago.
>>>
>>> Hth
>>>
>>> Regards,
>>> Miro
>>>
>>> On Feb 16, 2010, at 7:07 PM, Marko Milivojevic wrote:
>>>
>>>> Hello,
>>>>
>>>> You guys are missing an important thing here... RIPv1 does not
>>>> support
>>>> VLSM, but it DOES support subnetting, as long as masks are of equal
>>>> length... So, if you have two /24 subnets from major /8 network,
>>>> they
>>>> will be sent out. Now, the thing here is... if you use RIPv1, it
>>>> cannot handle variable masks, because it's ... classless. Try
>>>> configuring all interfaces on your routers with the same mask and
>>>> see
>>>> what happens.
>>>>
>>>> --
>>>> Marko Milivojevic - CCIE #18427
>>>> Senior Technical Instructor - IPexpert
>>>>
>>>> Mailto: markom_at_ipexpert.com
>>>> Telephone: +1.810.326.1444
>>>> Fax: +1.810.454.0130
>>>> R&S Video on Demand Demo: http://bit.ly/aFyrU4
>>>>
>>>> On Tue, Feb 16, 2010 at 17:55, Roy Waterman
>>>> <roy.waterman_at_gmail.com>
>>>> wrote:
>>>>>
>>>>> Actually all disregard my last post :)
>>>>> Labbed it up exactly and saw this:
>>>>>
>>>>> R1#
>>>>> RIP: sending v1 update to 255.255.255.255 via Serial0/0.12
>>>>> (10.1.0.1)
>>>>> RIP: build update entries - suppressing null update
>>>>> R1#
>>>>>
>>>>> R2#
>>>>> RIP: sending v1 update to 255.255.255.255 via Serial0/0.21
>>>>> (10.1.0.2)
>>>>> RIP: build update entries - suppressing null update
>>>>>
>>>>> ----------------
>>>>>
>>>>> If a /24 mask is used instead of the /16 between R1 & R2, it
>>>>> changes
>>>>> things:
>>>>>
>>>>> RIP: sending v1 update to 255.255.255.255 via Loopback0 (10.2.0.1)
>>>>> RIP: build update entries
>>>>> B B B B subnet 10.1.0.0 metric 1
>>>>> B B B B subnet 10.3.0.0 metric 2
>>>>>
>>>>> R1#sh ip ro rip
>>>>> B B 10.0.0.0/24 is subnetted, 5 subnets
>>>>> R B B B 10.3.0.0 [120/1] via 10.1.0.2, 00:00:06, Serial0/0.12
>>>>>
>>>>>
>>>>> Gotta love RIPv1.
>>>>>
>>>>>
>>>>> Regards
>>>>> Roy
>>>>>
>>>>>
>>>>>
>>>>> On 16 February 2010 17:46, Tony Schaffran (GS)
>>>>> <groupstudy_at_cconlinelabs.com>wrote:
>>>>>
>>>>>> I am not sure. B This is not what I would expect of RIPv1.
>>>>>>
>>>>>> Maybe somebody with a more technical answer can chime in.
>>>>>>
>>>>>> As this has not been a topic of the CCIE blueprint for some
>>>>>> time now
>>>>>> and I
>>>>>> have not come across this in an actual network for even longer,
>>>>>> I just
>>>>>> do
>>>>>> not have any more knowledge of it.
>>>>>>
>>>>>> Sorry.
>>>>>>
>>>>>> Tony Schaffran
>>>>>> Sr. Network Consultant
>>>>>> CCIE #11071
>>>>>> CCNP, CCNA, CCDA,
>>>>>> NNCDS, NNCSS, CNE, MCSE
>>>>>>
>>>>>> CCOnlineLabs
>>>>>> Your #1 choice for online Cisco rack rentals.
>>>>>>
>>>>>>
>>>>>> From: Sarad [mailto:tosara_at_gmail.com]
>>>>>> Sent: Tuesday, February 16, 2010 9:42 AM
>>>>>> To: groupstudy_at_cconlinelabs.com
>>>>>> Cc: Nadeem Rafi; Cisco certification
>>>>>> Subject: Re: RIP V1 VLSM
>>>>>>
>>>>>> Hi tony,
>>>>>>
>>>>>> But as it is a contiguous network it should advertise /16 isnt
>>>>>> it? . I
>>>>>> initially thought it should also advertise /24 :(. I am trying
>>>>>> to catch
>>>>>> what
>>>>>> happen with the debug but it doesnt show much pls share if you
>>>>>> can
>>>>>> capture
>>>>>> anything on debug which shows why it is not advertising.
>>>>>>
>>>>>> Sara
>>>>>> On Tue, Feb 16, 2010 at 11:05 PM, Tony Schaffran (GS)
>>>>>> <groupstudy_at_cconlinelabs.com> wrote:
>>>>>> Interesting. B I would not even expect the /16 to be
>>>>>> advertised, but it
>>>>>> is
>>>>>> as
>>>>>> you describe.
>>>>>>
>>>>>> Also as you describe, the /24 definitely does not get advertised.
>>>>>>
>>>>>> Tony Schaffran
>>>>>> Sr. Network Consultant
>>>>>> CCIE #11071
>>>>>> CCNP, CCNA, CCDA,
>>>>>> NNCDS, NNCSS, CNE, MCSE
>>>>>>
>>>>>> CCOnlineLabs
>>>>>> Your #1 choice for online Cisco rack rentals.
>>>>>>
>>>>>>
>>>>>> From: Sarad [mailto:tosara_at_gmail.com]
>>>>>> Sent: Tuesday, February 16, 2010 9:31 AM
>>>>>> To: groupstudy_at_cconlinelabs.com
>>>>>> Cc: Nadeem Rafi; Cisco certification
>>>>>>
>>>>>> Subject: Re: RIP V1 VLSM
>>>>>>
>>>>>> Yes I have set it up, as per theory of RIP as it is a contiguous
>>>>>> network
>>>>>> (10
>>>>>> range) it should send it. When the loopback is a /16 it sends the
>>>>>> loopbacks
>>>>>> but when I change it to /24 it doesnt send it. So is this a
>>>>>> illustration of
>>>>>> RIPV1 does not support VLSM ?
>>>>>>
>>>>>>
>>>>>> On Tue, Feb 16, 2010 at 10:39 PM, Tony Schaffran (GS)
>>>>>> <groupstudy_at_cconlinelabs.com> wrote:
>>>>>> I do not think RIPv1 will be sending /16
>>>>>>
>>>>>> RIPv1 is classless and 10.x.x.x is /8
>>>>>>
>>>>>> Have you configured this in a lba to see for yourself?
>>>>>>
>>>>>> Tony Schaffran
>>>>>> Sr. Network Consultant
>>>>>> CCIE #11071
>>>>>> CCNP, CCNA, CCDA,
>>>>>> NNCDS, NNCSS, CNE, MCSE
>>>>>>
>>>>>> CCOnlineLabs
>>>>>> Your #1 choice for online Cisco rack rentals.
>>>>>>
>>>>>>
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On
>>>>>> Behalf Of
>>>>>> Nadeem Rafi
>>>>>> Sent: Tuesday, February 16, 2010 8:53 AM
>>>>>> To: Sarad
>>>>>> Cc: Cisco certification
>>>>>> Subject: Re: RIP V1 VLSM
>>>>>>
>>>>>> you will not be able to see /24 as rip v1 will be sending /16
>>>>>> major
>>>>>> network
>>>>>> only.
>>>>>>
>>>>>> HTH
>>>>>>
>>>>>> On Tue, Feb 16, 2010 at 7:39 PM, Sarad <tosara_at_gmail.com> wrote:
>>>>>>
>>>>>>> Hi Expert,
>>>>>>>
>>>>>>> If I have the following scenario, that is two routers
>>>>>>> connected back
>>>>>>> to
>>>>>>> back
>>>>>>> with a 10 range /16 ip & there are two loopbacks configured on
>>>>>>> each
>>>>>>
>>>>>> router
>>>>>>>
>>>>>>> with the same class IPs. If I run RIPV1 on this. Will it
>>>>>>> advertise my
>>>>>>> loopbacks to each other.
>>>>>>>
>>>>>>> B B B R1
>>>>>>> R2
>>>>>>> S0 - 10.1.0.1/16 <---------------------------> S0 -10.1.0.2/16
>>>>>>> L0 - 10.2.0.1/24 B B B B B B B B B B B B B B B
>>>>>>> B B B
>>>>>>> B B L0 -
>>>>>>
>>>>>> 10.3.0.1/24
>>>>>>>
>>>>>>> Regards
>>>>>>> Sara
>>>>>>>
>>>>>>>
>>>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________________________________
 

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>>
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>>
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>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Regards
>>>>> Roy
>>>>>
>>>>>
>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>
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Received on Wed Feb 17 2010 - 19:30:17 ART