Re: RIP V1 VLSM

Hi Roy,

Yeah it's not in the lab any more But this behavior made me curious &
wanted to share it with the group, In your lab you have use /24 for all the
interfaces then yes it works. But if you use /16 on the physical interface &
/24 in the loopback interface does it work?

Sara

On Tue, Feb 16, 2010 at 11:14 PM, Roy Waterman <roy.waterman_at_gmail.com>wrote:

> Sarad
>
> By definition RIPv1 does not support VLSM.
> Hence routes are sent out (subject to conditions) without the mask..i.e
> subnet 10.2.0.0 & subnet 10.3.0.0
> VLSM only came into play with RIPv2.
> Yes it does send it (please check my last post), as 10.2.0.0 & 10.3.0.0
> without a mask.
> So the receiving router needs to select which mask to use, & i believe it
> does this based on the mask thats configured on the receiving interface (/24
> here).
> So in this case a /24 mask is assumed.
> Hence you will see:
>
> 10.2.0.0/24 on R2
> 10.3.0.0/24 on R1
>
> Now there are quite a few rules regarding RIPv1 and autosummary.
> Jeff Doyle covers RIPv1 v well.
>
> However, again, to reiterate Tyson Scott, you really dont need to concern
> yourself with this stuff unless you use RIPv1 in production ( I would hope
> not). Its not in the lab.
>
> The proof of the pudding is in the eating.
> I ran a similar topology with 10.1.1.1/24 on R1 and 10.2.2.2/24 on R2.
> Check the RIB:
>
> R1#sh ip ro rip
> 10.0.0.0/24 is subnetted, 6 subnets
> R 10.2.2.0 [120/1] via 10.1.12.2, 00:00:06, Serial0/0.12
> <--------------------------------------------
> R 10.1.200.0 [120/1] via 10.1.12.2, 00:00:06, Serial0/0.12
>
> R2#sh ip ro rip
> 10.0.0.0/24 is subnetted, 4 subnets
> R 10.1.1.0 [120/1] via 10.1.12.1, 00:00:12, Serial0/0.21
> <-------------------------------------
>
>
> Its all based on the assumption of what mask to apply to the route coming
> in.
> You can see that R1 & R2 decided upon apply a /24 mask.
>
> Regards
> Roy
>
>
>
> On 16 February 2010 17:30, Sarad <tosara_at_gmail.com> wrote:
>
>> 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.
>> > >
>> > > R1
>> > > R2
>> > > S0 - 10.1.0.1/16 <---------------------------> S0 -10.1.0.2/16
>> > > L0 - 10.2.0.1/24 L0 -
>> > 10.3.0.1/24
>> > >
>> > > Regards
>> > > Sara
>> > >
>> > >
>> > > 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
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>>
>>
>>
>>
>>
>>
>>
>
>
> --
> Regards
> Roy

Blogs and organic groups at http://www.ccie.net
Received on Tue Feb 16 2010 - 23:24:13 ART