RIP |V1y mind open!

Desert_dweller5 · ‎06-14-2010

confused about the title maybe you know how i feel about Rip Version 1.

I think this is the single most confusing thing i've encountered in my short networking career.

i want to see if i understand this correctly.

this is what i think i know :

it seems like inside the 172.16.5.0/24 network everyone’s subnet mask is set to /24 but because RIP v1 can’t deal with sending subnet masks through a foreighn network the router has to summarize to make it fall on the class boundary. (this is about discontiguous networks)

that's why this statement:

Yes: Does the network have the same subnet mask as the interface that sources the update?

from:

http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a0080093fd8.shtml

very much confused me.

in summary of that point.

RIP version one has nothing to do with subnet masks. when rip v1 was invented there wasn't any need of subnet masks.

RIP v1 NOT EQUAL TO Subnet masks

which is why this next part is confusing:

Cisco books and examples consistently use network addresses with the first octet being a class A or class B but using a /16 or /24 for class A instead of the proper /8 and a /24 for class B network addresses instead of the proper /16. why don't they make it easier to understand and use the CORRECT subnet masks or just leave them out of the conversation all together because RIP DOESN'T concern or use subnet masking! My mind is RIPed open. either you USE subnet masks or you DONT USE, subnet masks. Make up your mind and stick to 1 position. Thanks in advance for your help. a quick response will be greatly apreciated as i have a test in roughly 36 hours. Regards to all.

Ganesh Hariharan · ‎06-14-2010

confused about the title maybe you know how i feel about Rip Version 1.
I think this is the single most confusing thing i've encountered in my short networking career.  
i want to see if i understand this correctly.
this is what i think i know :
it
seems like inside the 172.16.5.0/24 network everyone’s subnet mask is
set to /24 but because RIP v1 can’t deal with sending subnet masks
through a foreighn network the router has to summarize to make it fall
on the class boundary.    (this is about discontiguous networks)
that's why this statement:
Yes: Does the network have the same subnet mask as the interface that sources the update?
from:
http://www.cisco.com/en/US/tech/tk364/technologies_tech_note09186a0080093fd8.shtml
very much confused me.  
in summary of that point. 
RIP version one has nothing to do with subnet masks. when rip v1 was invented there wasn't any need of subnet masks. 
RIP v1 NOT EQUAL TO Subnet masks 
which is why this next part is confusing: 
Cisco
books and examples consistently use network addresses with the first
octet being a class A or class B but using a /16 or /24 for class A
instead of the proper /8 and a /24 for class B network addresses
instead of the proper /16.  why don't they make it easier to understand
and use the CORRECT subnet masks or just leave them out of the
conversation all together because RIP DOESN'T concern or use subnet
masking!  My mind is RIPed open.  either you USE subnet masks or you
DONT USE, subnet masks. Make up your mind and stick to 1 position.  
Thanks in advance for your help. a quick response will be greatly
apreciated as i have a test in roughly 36 hours.  Regards to all.

Hi ,

As RIP V1 is classful Routing Protocol that do not send subnet mask information when a route update is sent out. All devices in the network must use the same subnet mask and assume the following assumptions:-

* The classful routing protocols support FLSM (Fixed Length Subnet Masking) and it does not support VLSM (Variable Length Subnet Masking).

* The network can be subnetted but within a given network all subnets will be the same size. This results in a behavior that an interface will advertise subnets of its network that have the same subnet mask as the interface but will not advertise subnets of that network with a different subnet mask. That is the reason that the routing update does not contain subnet mask information.

* The networks are contiguous and that you should be able to get from one subnet of the network to any other subnet of that network without going outside the network. This leads to the behavior that they always automatically summarize at network boundaries.

Hope to Help !!

Ganesh.H

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