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Rip - Classful subnets

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Rip - Classful subnets

neuralping
Using Boson NetSim 6 simulator - Lab 6 RIP. The simulator clearly states RIP has to have classful network number. However,There are a couple of classless network numbers being used on routers 3 and 4. Router 3 would not advertise routes when using a classful network of 197.10.0.0. What am I missing. Can rip use classless network numbers?

Router1
network 160.10.0.0
network 175.10.0.0

Router2
network 160.10.0.0

Router3
network 175.10.0.0
network 180.10.0.0
network 197.10.1.0

Router4
network 180.10.0.0
network 195.10.1.0
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    CG IT

    Version 1 doesn't. Version1 is stricktly classful.

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    neuralping

    I saw documentation where RIPv1 does not send subnet mask information when advertising routes which is the reason why you need to use classful networks numbers. The strange thing is Router 4 advertising network 195.10.1.0 gets sent out to the other routers with no problem. Just router 3 with network 197.10.1.0 won't advertise when it's classless. I watched using debug ip rip and it never got sent out but on router 4 195.10.1.0 gets advertised.

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    CG IT

    RIP version 2 is classless and supports VLSM. So if you have IP classess command in the configuration, use RIP 2 to advertise.

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    neuralping

    OK. I got it. Thanks for the help.

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    neuralping

    I also noticed both networks are ethernet.

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    NetMan1958

    Why you say "However, There are a couple of classless network numbers being used on routers 3 and 4"

    I'm not saying you are wrong as I don't have that NetSim you are using so I can't see everything you see. I am curious though.

    Also, you might be interested in this article:
    http://www.cisco.com/application/pdf/paws/13724/55.pdf

    The take-away is that if RIPv1 advertises a route across a major network boundry then it automatically summarizes it. However, if it advertises the route across a link that is part of the same major network, then it sends the subnet mask also.

    For example:
    172.16.1.0/24 -> 172.20.1.0/24 -> 172.16.2.0/24
    The router advertising 172.16.1.0/24 summarizes the route to 172.16.0.0

    However:
    172.16.1.0/24 -> 172.16.3.0/24 -> 172.16.2.0/24
    The router advertising 172.16.1.0 sends the route as 172.16.1.0 255.255.255.0

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    CG IT

    if he's doing VLSM, RIPv2

  • +
    0 Votes
    CG IT

    Version 1 doesn't. Version1 is stricktly classful.

    +
    0 Votes
    neuralping

    I saw documentation where RIPv1 does not send subnet mask information when advertising routes which is the reason why you need to use classful networks numbers. The strange thing is Router 4 advertising network 195.10.1.0 gets sent out to the other routers with no problem. Just router 3 with network 197.10.1.0 won't advertise when it's classless. I watched using debug ip rip and it never got sent out but on router 4 195.10.1.0 gets advertised.

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    0 Votes
    CG IT

    RIP version 2 is classless and supports VLSM. So if you have IP classess command in the configuration, use RIP 2 to advertise.

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    0 Votes
    neuralping

    OK. I got it. Thanks for the help.

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    0 Votes
    neuralping

    I also noticed both networks are ethernet.

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    0 Votes
    NetMan1958

    Why you say "However, There are a couple of classless network numbers being used on routers 3 and 4"

    I'm not saying you are wrong as I don't have that NetSim you are using so I can't see everything you see. I am curious though.

    Also, you might be interested in this article:
    http://www.cisco.com/application/pdf/paws/13724/55.pdf

    The take-away is that if RIPv1 advertises a route across a major network boundry then it automatically summarizes it. However, if it advertises the route across a link that is part of the same major network, then it sends the subnet mask also.

    For example:
    172.16.1.0/24 -> 172.20.1.0/24 -> 172.16.2.0/24
    The router advertising 172.16.1.0/24 summarizes the route to 172.16.0.0

    However:
    172.16.1.0/24 -> 172.16.3.0/24 -> 172.16.2.0/24
    The router advertising 172.16.1.0 sends the route as 172.16.1.0 255.255.255.0

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    0 Votes
    CG IT

    if he's doing VLSM, RIPv2