CCNP - Changing IP schemes

Author

Changing IP schemes

biljen

2002-05-29, 1:32 pm

I work at a school district in New Jersey and was wondering, I have a router that connects to a network with the Network address of 172.16.30.0/24 via 172.16.3.2/32, If I were to change the Network Address 172.16.30.0/24 to 172.16.8.0/21 on the destination router to give me more host addresses would I still be able to accomplish this without changing the the other network Addresses and still have them communicate. And will the routing tables pick up that new information on all the other routers in the district?

Thanks for any help you can give me, this could mean a promotion

LANlord

2002-05-29, 3:31 pm

What routing protocol are you using? Remember, RIP1 and IGRP don't do VLSM, they are classful. If you're using EIGRP or some other protocol that support VLSM, I see no reason why it wouldn't work... based on the information you gave. That is the basic functionality of routing...moving data from one network to another. So, as long as these two networks are aware of each other, it should be fine. If you have a test lab, do it there first.

biljen

2002-05-29, 4:16 pm

But if it's reaching that network via 172.16.3.2/32 wouldn't the /32 indicate that it is using EIGRP or a protocol that supports VLSM, Because the destination Network is /24 dissimilar subnet masks?
and RIP only supports identical subnet masks right?

subnet__zero

2002-05-30, 9:03 am

The /32 mask is interesting. . . how is it going to work??

LANlord

2002-05-30, 9:39 am

The /32 mask just defines a specific host or interface(usually a loopback address).

Detour

2002-05-30, 11:32 am

quote:
Originally posted by biljen
I work at a school district in New Jersey and was wondering, I have a router that connects to a network with the Network address of 172.16.30.0/24 via 172.16.3.2/32, If I were to change the Network Address 172.16.30.0/24 to 172.16.8.0/21 on the destination router to give me more host addresses would I still be able to accomplish this without changing the the other network Addresses and still have them communicate. And will the routing tables pick up that new information on all the other routers in the district?

Thanks for any help you can give me, this could mean a promotion

i'm a bit confused by your description. 172.16.30.0/24(via 172.16.3.2) wouldn't be a directly connected network. That's at least a hop away.

doctorcisco

2002-05-30, 1:33 pm

quote:
Originally posted by biljen
I work at a school district in New Jersey and was wondering, I have a router that connects to a network with the Network address of 172.16.30.0/24 via 172.16.3.2/32, If I were to change the Network Address 172.16.30.0/24 to 172.16.8.0/21 on the destination router to give me more host addresses would I still be able to accomplish this without changing the the other network Addresses and still have them communicate. And will the routing tables pick up that new information on all the other routers in the district?

Thanks for any help you can give me, this could mean a promotion

Are you SURE it's not via 172.16.3.2/30 instead? What are the other interface addresses on your router that attaches to the LAN network 172.16.30.0/24?

It's possible what we have here is a serial or whatever interface using IP unnumbered and a static route to take traffic offsite. It is also conceivable that they're using the "new" /31 bit masks for the serial connections (see rfc 3021 and http://www.cisco.com/univercd/cc/td...tm#xtocid104194 ).

In any case, you'd want to make sure the 172.16.8.0/21 address space is completely unused throughout the network. If so, and if you are using a VLSM-capable routing protocol, and there are no static routes to or from the current 172.16.30.0/24 network, the change should work regardless of the nature of the other connections or addressing.

HTH,
doc

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