Re: RIP V1 VLSM

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
> > >
> > >
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-- 
Regards
Roy
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