CIDR is compatible with RIPv1? I think not ... Why RIPv1supernets learning?

hilbert69hilbert69 Registered Users Posts: 4 ■□□□□□□□□□
in CCNA & CCENT
I have a question .... if you have 2 routers directly connected. The first configured with RIPv1.The second configured with RIPv2.
The router configured with RIPv2 redistribute a static route 172.16.0.0/12, as it is possible that the router configured with RIPv1 learn this route? I've checked with Packet Tracer and GNS3 ... Someone can explain me.Thank you.
Raul.
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  • ehndeehnde Member Posts: 1,103
    172.16.0.0/12 is a classful route, that is why RIPv1 can understand it. If you break down that /12 to, say, a /23 - then your RIPv1 router will still see it as 172.16.0.0/12.
    Climb a mountain, tell no one.
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  • sasprosaspro Member Posts: 114
    172.16.0.0 is a class B address. Shouldn't that be a /16?
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  • ehndeehnde Member Posts: 1,103
    saspro wrote: »
    172.16.0.0 is a class B address. Shouldn't that be a /16?

    Yes, you're right. I got my bit boundaries bass ackwards. Sorry hadn't had enough coffee yet.
    Climb a mountain, tell no one.
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  • sasprosaspro Member Posts: 114
    ehnde wrote: »
    Yes, you're right. I got my bit boundaries bass ackwards. Sorry hadn't had enough coffee yet.

    It's afternoon over here so I'm wired on coffee by now (whilst running through practice exams at work)
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  • hilbert69hilbert69 Registered Users Posts: 4 ■□□□□□□□□□
    ehnde wrote: »
    172.16.0.0/12 is a classful route, that is why RIPv1 can understand it. If you break down that /12 to, say, a /23 - then your RIPv1 router will still see it as 172.16.0.0/12.
    I do not agree with that 172.16.0.0/12 is a classfull route,Notice that the /12 mask (255.240.0.0) is less than the default classful mask /16 (255.255.0.0).Classfull routes have /8,/16 or /24.The route 172.16.0.0/12 is the summarization of the following networks:from 172.16.0.0/16 to 172.31.0.0/16.Conclusions:172.16.0.0/12 is a "supernet".Thank you.
    Raul.
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  • sasprosaspro Member Posts: 114
    hilbert69 wrote: »
    I do not agree with that 172.16.0.0/12 is a classfull route,Notice that the /12 mask (255.240.0.0) is less than the default classful mask /16 (255.255.0.0).Classfull routes have /8,/16 or /24.The route 172.16.0.0/12 is the summarization of the following networks:from 172.16.0.0/16 to 172.31.0.0/16.Conclusions:172.16.0.0/12 is a "supernet".Thank you.
    Raul.

    Maybe I do need more coffee as well (or to finish up reading about some of this).

    Doesn't redistribution "translate" to other protocols? This would mean the v2 router would send it to the v1 router in a format the v1 router understands.

    What does the routing table on Router 1 show?
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  • hilbert69hilbert69 Registered Users Posts: 4 ■□□□□□□□□□
    This is the resultat:
    R2#sh ip route
    1.0.0.0/30 is subnetted, 1 subnets
    C 1.1.1.0 is directly connected, FastEthernet0/0
    R 172.16.0.0/12 [120/1] via 1.1.1.1, 00:00:26, FastEthernet0/0
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  • MrRyteMrRyte Member Posts: 347 ■■■■□□□□□□
    hilbert69 wrote: »
    This is the resultat:
    R2#sh ip route
    1.0.0.0/30 is subnetted, 1 subnets
    C 1.1.1.0 is directly connected, FastEthernet0/0
    R 172.16.0.0/12 [120/1] via 1.1.1.1, 00:00:26, FastEthernet0/0
    If RIPv1 is the routing protocol then shouldn't that be /16?
    NEXT UP: CompTIA Security+ :study:

    Life is a matter of choice not chance. The path to your destiny will be paved by the decisions that you make every day.
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  • Excellent1Excellent1 Member Posts: 462 ■■■■■■■□□□
    ehnde wrote: »
    Yes, you're right. I got my bit boundaries bass ackwards. Sorry hadn't had enough coffee yet.

    From reading some of the replies in this thread, I get the feeling you won't be living this one down for a while... icon_wink.gif

    Just giving you a hard time, man. It's all in good fun. :)
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  • hilbert69hilbert69 Registered Users Posts: 4 ■□□□□□□□□□
    MrRyte wrote: »
    If RIPv1 is the routing protocol then shouldn't that be /16?
    I think so too. But I have tried in the Packet Tracer and GNS3 and achieving the same result. It's very strange assuming that RIPv1 does not support CIDR.
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  • MrRyteMrRyte Member Posts: 347 ■■■■□□□□□□
    hilbert69 wrote: »
    I think so too. But I have tried in the Packet Tracer and GNS3 and achieving the same result. It's very strange assuming that RIPv1 does not support CIDR.
    According to this link:
    Cisco IOS IP and IP Routing Command Reference, Release 12.1 - RIP Commands  [Cisco IOS Software Releases 12.1 Mainline] - Cisco Systems


    Command

    Description



    ip rip receive version

    Specifies a RIP version to receive on an interface basis.



    ip rip send version

    Specifies a RIP version to send on an interface basis.



    show ip protocols

    Displays the parameters and current state of the active routing protocol process.





    It's possible to have a router send/receive two different RIP versions.
    Can you post us the "show protocols" from the RIPv1 configured router?
    NEXT UP: CompTIA Security+ :study:

    Life is a matter of choice not chance. The path to your destiny will be paved by the decisions that you make every day.
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