router configuration and subnetting

hello,
plz i need somebody help about this router configuration
I have 192.168.1.0 has been allocated for my network . I need to use 4 routers and 4 switchs beacuse we have four different departments
library: 59 hosts machines
account; 54 hosts machines
payroll 17 host
warehouse 8 host
so i had configured all the fastethernet routers using these addreses below.
routers 1 fastethernet for the library, 192.168.1.62 /26
routers 2 , for the account, 192.168.1.66 /26
routers 3, for the payroll, 192.168.1.158/27
router 4, for the warehouse.192.168.1.161 /28
they all connects to four switches as well as computers
in this scenario routing protocol is using for all the routers like eigrp
i have got two questions , which addresses am i going to use for my serial interface wan links , and also which addresses to be advertised on each routers ? i hope u understand my questions. plz a bit of explanations will be needed just like to compare it to what i have got beacause im not really sure about it . it would not allow me to ping to another serial interfaces which i really think it could be wrong.

which addresses am i going to use for my serial interface wan links , and also which addresses to be advertised on each routers ? i hope u understand my questions. plz a bit of explanations will be needed just like to compare it to what i have got beacause im not really sure about it . it would not allow me to ping to another serial interfaces which i really think it could be wrong.

Hello terryboob,

Your addressing scheme seams OK. For serial (point to point) links. It is optimal to use a range with the /30 mask since it consumes the minimum number of IPs 2. For example:

192.168.1.176/30
192.168.1.180/30
192.168.1.184/30
192.168.1.188/30

These all fall just after your last subnet (warehouse). You could also use a different range changing the 3rd octet, for example:

192.168.2.4/30
192.168.2.8/30
192.168.2.12/30
....
and so on.

I personally prefer the second scheme since it makes it more obvious for administrators to figure out that these IPs are for serial links, and it also isolates there ranges from your 4 department subnets which could increase/change in future.

By the way, 192.168.x.x is not the only private range. you could use 10.x.x.x, or 172.16.x.x to 172.31.x.x.

For EIGRP configuration, advertise the classfull networks you have and the router will take care of the rest. I'm assuming that you will use 192.168.2.x range. So you need to do the following (in every router):

[code:1]
Router(config-router)# network 192.168.1.0
Router(config-router)# network 192.168.2.0
[/code:1]

In general, Also, don't forget to turn OFF auto-summary:

[code:1]
Router(config-router)# no auto-summary
[/code:1]

EIGRP works best without auto-summary. Thats as far as I know.

thanks for your time ........solo.

so when configuring serial interface (wan links) is it advisable to use private addresses rather than using ip address allocated for the entire network design ? thats what i dont really understand because i thought that i can use ip allocated address for my serial interface.
and also i assuming im using the second address for my serial interface 192.168.2.xx so my network advertised can be 192.168.1.0 and 192.168.2.0 in each routers ? thanks i will try that

so when configuring serial interface (wan links) is it advisable to use private addresses rather than using ip address allocated for the entire network design ? thats what i dont really understand because i thought that i can use ip allocated address for my serial interface.

I'm not sure I understand what is an "ip allocated address"? Do you mean a public IP?

You can allocate either a private range or a public range. If your WAN link is connected to an ISP or an external network, then you typically assign it a PUBLIC ip that was assigned to the network, this is because you need the internet to be able to reach your network. If the WAN link is internal to your network, you can use a private range. If you use a public range for that (assuming you own this range) then your consuming your public addresses, it better be for a reason, for example, if one of the sides of the WAN link is running say a web server that you want to be accessible from the internet.

To make it simple. Private addresses are free but not reachable from outside. Public addresses are costly but are reachable from outside.

what i mean about ip allocated address is the address i have been given to design my network it could be private or public.......i havent got much time to configure the addresses you gave to me i hope it will work on my routers so that i can be able to ping serial interfaces thanks

solo.yes i wanna ask you one question.........my router must connect to external network like isp......like u said.so which address could be best to use on the routers serial interface .......these department is remotely connect to network via router... i need to perform vslm on which subnets address ? and also i need to advertise the addresses