Re: RIP V1 VLSM

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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>>>>
>>>>
>>>
>>>
>>> --
>>> Regards
>>> Roy
>>>
>>>
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Received on Tue Feb 16 2010 - 21:17:19 ART