03-20-2002 11:14 AM - edited 03-01-2019 08:57 PM
Greetings. I have a lab that now requires a routed interface. The setup works like this. A router with a class A address and 24 bit mask (ex. 21.6.225.254/24) has an attached Catalyst 4006 with a L3 card. All lab nodes were configured on the same network, same subnet mask. Static routing. If I change the router mask to 30 bits (21.6.225.254/30) and assign 21.6.225.253/30 to one subinterface on the catalyst - what happens?
That is, I'd like to avoid changing the subnet masks on each lab node. So if they remain at a 24 bit mask, is this a problem? I would need to give the lab vlan an interface, so I'd be adding a 21.6.225.x/24. So the catalyst would have, for example, int Gig3.1 21.6.225.253/30 and int Gig3.2 21.6.225.250/24. Would this work?
03-20-2002 12:13 PM
"So the catalyst would have, for example, int Gig3.1 21.6.225.253/30 and int Gig3.2 21.6.225.250/24. Would this work?"
No. The 21.6.225.0/24 subnet, and the 21.6.225.252/30 subnet overlap.
I am also not quite sure what you need to do. Do you want to split the 21.6.225.0/24 network? Perhaps 21.6.225.0/25 and 21.6.225.128/25?
03-20-2002 12:31 PM
Trouble is, the upstream router isn't mine, and neither are the lab nodes. So I have to try and fix their problems in my limited sphere. I know the 24 and 30 bit networks overlap, I just didn't know if I could trick the box into letting me do it..
03-22-2002 10:41 AM
on the same box, you can not have address/mask overlapping. The device won't accept it and will give you an error message.
03-24-2002 12:06 PM
you would still need to change the default gateway of all the lab nodes, wouldn't you?
Is this what you have:
router(.254)-------/24-------cat4006-------/24-------(.x)labnodes
and labnode's default gateway is the router right?
so the catalyst 4006 is working only at layer 2.
now you want the cat4006 to route, right?
solution 1:
change router ip
router(y.z)-------/30-------(y.z-1)cat4006(.254)-------/24-------(.x)labnodes
if you can't change the router ip then you could:
router(.254)-------/30-------(.253)cat4006(.126)-------/25-------(.x)labnodes
but restricted to 0 < x < 126
is that clear???
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