Re: RIP V1 VLSM

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
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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
>> >
>> >
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>
>
> --
> Regards
> Roy
>
>
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