hello everyone, im just new here. i need some help regarding cisco PKT. i was configuring a router and getting this error.

i configured f0/0 with an ip add of 172.16.1.0 255.255.252.0 and f0/1 with 172.16.4.1 255.255.252.0. i ran show run command and got the right output....but...

when i ran the show ip route command, the output was different... i think it should be 172.16.1.0/22 instead of 172.16.0.0/22. i was confused and thinking which is right between me and the cisco pkt. ehehe. i hope someone could tell me if it's just a bug or what. THANKs.

Looks like it's trying to do classful routing. Have you put in an IP classless command?

it doesn't work in pkt. i think routing behavior has nothing to do here. i havent put any routing protocol yet. these are just directly connected network. i reconfigured f0/0 with the same ip but with a mask of /24 and i got the right output in show ip route which is 172.16.1.1/24. The problem is, i dont have any real router to try it.

That's normal behaviour. 172.16.1.1 /22 starts from 172.16.0.0 to 172.16.3.255 and it will display 172.16.0.0 on the table.

but i have already used the 172.16.0.0 with a /25 in other router. meaning to say i cant use any ip ranging from 172.16.0.0 -254 anymore in this router. i think, it should start with 172.16.1.1.

Baybars is correct.
The net id for 172.16.1.1/22 is 172.16.0.0/22.
Also the 172.16.0.0/25 you mention is only to 126 not 254. (i did not include the broadcast ip)
Do you really need a /22? Perhaps use 172.16.0.128/25, or do you really need 1000+ hosts on that subnet?

These subnets overlap

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@matgar, well i just wanted to borrow 1 bit from network add, but i couldn't use 255.255.254.0 mask. it wouldn't match the leftmost bits of the network add, i think.

if you guys have some time, could you please check this PKT . particularly the routing table, running config in R1 n R3. Thank you.

I don't have PT so i cant check your file, but I'm not sure why you won't accept what we are telling you.
172.16.0.0/25 will conflict with 172.16.0.0/22 or /23 /25 /21 as well for that matter.

I would suggest you use an online subnet calculator if your doubting us or need to have it visual before your eyes.

Try adding 172.16.1.0/22 and you will see that it states the net id 172.16.0.0 and that valid ip is 172.16.0.1 to 172.16.3.254 which means that you cannot use a subnet/ip that falls within that range on another place.

i believe in you. yea you're right. thanks. my fault was, i should have started the assigning of ip add with the network which has the largest number of hosts. sorry and thank you very much. it's all clear now.