need help: IP subnetting and connectivity problem

[makie]

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i'm trying to simulate a network made up of 5 subnetworks using a class b 172.100.18.0/18 address. i need to further subdivide such ip address into 5 to accommodate all 5 subnetworks. here's what i came up so far with.

sub-subnetworks needed: 5
available subnetwork divided into 8

current subnet mask: 255.255.192.0 (11111111.11111111.11000000.00000000)
new subnet mask: 255.255.248.0 (11111111.11111111.11111000.00000000)

what i did was this subdivide the network into this IP ranges

172.168.18.0-172.168.25.255
172.168.26.0-172.168.33.255
172.168.34.0-172.168.41.255
172.168.42.0-172.168.49.255
172.168.50.0-172.168.57.255
172.168.58.0-172.168.65.255
172.168.66.0-172.168.73.255
172.168.74.0-172.168.81.255

the problem now is that somewhere in the network upon configuring the router, it says that it overlaps with another IP range. pretty sure there is something wrong with how i divided the network (or maybe my subnetting is all wrong after all).

my question now is, how can if further subdivide such network (given the /18 subnet mask) properly/correctly?

[netcommando]

asa ra man tong mga ccna? diay subnetting diri mga bai, tabang... he he he

[netcommando]

bro, murag wa pa sila, ako sa sulay...

1st - 172.100.18.0/18 is not network add
2nd - /18 (.192.0) has 4 subnetworks in 172.100.0.0, 172.100.64.0, 172.100.128.0, 172.100.192.0
3rd - therefore 172.100.18.0 is a host belong to 1st subnet
4th - check again if this ip 172.168.18.0 255.255.248.0 is network or a host, remember ur in class B
and /21 has 4 bits subnetted, so start with 172.168.0.0, 172.168.8.0, 172.168.16.0 and so on...

i hope i'm correct, it has been 4 yrs+ ago then dealing subnets and supernets. Thanks i'm awaken.

[netcommando]

pahabol lang, ur doing it diay thru' binaries well it's good for great understanding the theory but as you go on, try the shortcuts. Let's just wait others to post theirs... para ma refresh pud ko

[coolnezz]

these are public IP addresses. are you running an ISP or a private network?

[makie]

@netcommando:

i really need some clarifications. i'm really not sure if i got this right but considering the 172.100.18.0/18 add, i think it is a network address because of the 255.255.192.0 mask (18 network bits and 14 host bits). i got the network up and running starting with a 172.168.0.0/16 add. my concern now is how to further subnet/subdivide the 172.100.18.0/18 subnet. or is this possible really in this scenario?

these are public IP addresses. are you running an ISP or a private network?

nope. im just simulating a network through packet tracer.

[netcommando]

so u hav no probs re 172.168.0.0/16, it's a legit class B.
it's the 172.100.18.0/18 the problem. from these data, i assumed that u have a router with 2 eth ports, 1serving the 172.168.0.0/16 and the other serving the 172.100.18.0/18.(mayb u can post the net scen)
we will start at d base network add class B for 172.100.18.0/16. from there you want to have subnetted network of 172.100.18.0/18. and practically u borrowed 2 bits on the 3rd octate that's why u hav now subnet mask of 255.255.192.0.
looking at this subnet 255.255.192.0, when u compute u will have 64 per subnet so,
1st subnet - 172.100.0.0. 255.255.192.0
2nd subnet - 172.100.64.0 255.255.192.0
3rd subnet - 172.100.128.0 255.255.192.0
4th subnet - 172.100.192.0 255.255.192.0
therefore, if u use subnet mask of 255.255.192.0, the IP add 172.100.18.0/18 is not a network but a host belong to 1st subnet. dili ta maka subnet ug host ip, pwedi i subnet ang network add lang.

Tnx bro, na refresh ko hinay2. he he he

[netcommando]

cont...
if u really insist of having a network 172.100.18.0, don't use /18 but /24. U can further subnet the 172.100.0.0/18 to 172.100.0.0/24, therefore below are ur network addresses.
1. 172.100.0.0/24
2. 172.100.1.0/24
3. 172.100.2.0/24
4. 172.100.3.0/24
..
19. 172.100.18.0/24 - mao na ni.....
..
64. 172.100.63.0/24
--------------------- diha ra kutob kay the next ana, overlap na ka sa 2nd subnet 172.100.64.0/18

i could be wrong but that's what i recall regarding subnetting. again, tnx, medyo na refresh ko.

[makie]

@netcommando:

tama diay, if i have to subnet 172.100.18.0/18, i have to use the /24 mask. i can only further subnet the subnets 172.100.18.0/18, 172.100.18.64/18, 172.100.18.0/128, and 172.100.18.0/192. i got confused with the "network bits" thinking that having a 255.255.192.0 subnet mask makes the whole 172.100.18.0/18 a subnetwork. bale 172.100.18.0/18 is within the 172.100.18.0-172.100.163.255 range, so such range is the one that can be subdivided. thanks a lot.

[netcommando]

Thanks a lot bro, na refresh jud ko, he he he