RE: [FW1] Nokia RIPv1 and subnets

["Felicetti, Stephen A." <SA_Felicetti@FW1-NOSPAMfccc.edu>]

Thanks for the clarification Andrew, maybe you can expand it a bit for me.
Here was the scenario:

e0	x.x.1.0/20
e1	x.x.16.0/20
e2	x.x.64.0/20
e3	x.x.80.0/28

x.x is a class B network. I was not receiving RIP broadcasts about e3 until
I changed the mask to 20, to match the others.
If RIPv1 assumes the mask from the class, why would it then care that I used
different masks on the interfaces.

Thanks,
Steve

-----Original Message-----
From: andrew.2.shore@bt.com [mailto:andrew.2.shore@bt.com]
Sent: Thursday, February 22, 2001 9:06 AM
To: SA_Felicetti@fccc.edu; fw-1-mailinglist@lists.us.checkpoint.com
Subject: RE: [FW1] Nokia RIPv1 and subnets


This is not quite right.

RIP version 1 is a classfull protocol ie 1.0.0.0 - 126.255.255.255 is a
class A network with mask 255.255.255.0 etc. Therefore, RIP V1 does not
support subnet masks at all the mask is assumed by the class.

RIP V 2 is classless which means it does not use the address to determine
the mask it carries it.

Regards


Andrew Shore
BTcd 
Information Systems Engineering
Internet & Multimedia 


-----Original Message-----
From: Felicetti, Stephen A. [mailto:SA_Felicetti@fccc.edu]
Sent: 22 February 2001 13:43
To: 'fw-1-mailinglist@lists.us.checkpoint.com'
Subject: [FW1] Nokia RIPv1 and subnets


This is more of an informational message about something I encountered while
configuring RIPv1. As it turns out this problem is a limitation of the RIPv1
protocol, not the Nokia or FW-1 product. I thought it would be useful in
case anyone try's what I did, and spent a day trying to figure it out....

I have an IP440 with 4 ethernet interfaces. In order to cut down the amount
of available networks on each leg, I had originally used different subnet
masks for each interface.
I then found out that RIPv1 doesn't support different subnet masks on the
same router, so I had to make them all the same. This wasn't a problem, as
we have plenty of IPs to go around. Once I made the change, everything
worked nicely together.

However, if your situation is different and you must subnet, you have to use
a different routing protocol, or switch to RIPv2. Due to our existing
network setup, we weren't able to switch.

Thanks,
Steve Felicetti


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