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classful and classless

workfrom925workfrom925 Member Posts: 196
in CCNA & CCENT
So I've learned there are classful and classless routing protocols, and there are classful and classless routing behavior.

I understand a classless protocol such as RIPv2 can have either classful or classless routing behavior; and a classful protocol such as RIPv1 can have classful routing behavior. But how does a classful protocol such as RIPv1 work with classless routing behavior? How is the routing different from classful routing behavior for RIPv1?
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    chapapachapapa Member Posts: 40 ■■□□□□□□□□
    classful routing doesn't send its subnet mask when sending a routing update
    classless routing sends its subnet mask when sending a routing update

    Example 1:
    lets say we have 3 routers connected and uses RIPv1(classful routing)
    host1 --R1 -- R2 -- R3 -- host2

    Host1's ip address: 172.16.10.10 GW: 172.16.10.1/24
    Host2's ip address: 172.168.11.10/24 GW: 172.16.11.1/24
    R1's serial ip address: 192.168.10.1/30
    R2's serial ip address connecting R1: 192.168.10.2/30
    R2's serial ip add connecting R3: 192.168.10.5/30
    R3's serial ip address: 192.168.10.6/30

    you configure RIPv1 on this network. host 1 and Host 2 will never be able to reach each others network why?
    because R1 would advertise his route with this address 172.16.0.0/16 since it is a major network and it detects he is on a border he will summarize same goes for R3.

    remember split horizon rule? R2 will never advertise R1 and R3's routes because of split horizon rule.

    to fix this issue, configure RIPv2 by typing version 2 on router configuration mode

    I hope this helps :)

    PS:To all, please correct me if I explained something that is wrong
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    workfrom925workfrom925 Member Posts: 196
    chapapa wrote: »
    classful routing doesn't send its subnet mask when sending a routing update
    classless routing sends its subnet mask when sending a routing update

    Example 1:
    lets say we have 3 routers connected and uses RIPv1(classful routing)
    host1 --R1 -- R2 -- R3 -- host2

    Host1's ip address: 172.16.10.10 GW: 172.16.10.1/24
    R1's serial ip address: 192.168.10.1/30
    R2's serial ip address connecting R1: 192.168.10.2/30
    R2's serial ip add connecting R3: 192.168.168.10.5/30
    R3's serial ip address: 172.168.11.10/24 GW: 172.16.11.1/24

    Do you mean PC2'w IP address: 172.168.11.10 GW: 172.16.11.1/24?
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    chapapachapapa Member Posts: 40 ■■□□□□□□□□
    workfrom925 wrote: »
    Do you mean PC2'w IP address: 172.168.11.10 GW: 172.16.11.1/24?

    yes. I updated the post. sorry for the errors
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    workfrom925workfrom925 Member Posts: 196
    chapapa wrote: »
    yes. I updated the post. sorry for the errors

    So you mean with classful routing protocol, classless routing is just impossible?
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