ip subnet zero help please

beginner_ccna

sorry all, i know alot has been posted on this subject

got a question where in a topology there are pc's and routers connected, with ip subnet zero configured

if for example theres a wan link using the 192.168.5.1/30 which is connected to a lan which is using 10.22.22.22/13

with the ip subnet zero command configured, will a pc which is connected to the wan on one side be able to ping to other lan side (10.22.22.22/13) through the wan link?

if is was configured with no ip subnet zero, what would be the outcome?

please could someone explain this as im finding it hard to get my head round this concept

Ltat42a

Years ago, IP addressing did not include the first & last subnet of an address range. For instance, using the IP 192.168.0.0/24, you were not able to use the range 192.168.0.0 - 192.168.0.255. Your first useable address range would be 192.168.1.0 - 192.168.1.255. As technology increased, we can now use the first subnet (or the zero subnet) to assign IP addresses. All modern day routers have ip subnet zero turned on by default.
In your question, the answer is yes, as long as you have a routing protocol or static routing configured.

hth

beginner_ccna

thanks for the info

so to confirm, if ip subnet zero was configured, i could use the 192.168.0.0/24 starting at the 192.168.0.0-192.168.0.255 range?

if there was no ip subnet configured, then we would start at 192.168.1.0 subnet?

xXErebuS

beginner_ccna wrote: »

thanks for the info

so to confirm, if ip subnet zero was configured, i could use the 192.168.0.0/24 starting at the 192.168.0.0-192.168.0.255 range?

if there was no ip subnet configured, then we would start at 192.168.1.0 subnet?

I think the wording is kind of fuzzy since 192.168.0.0/24 is classful

Breaking 192.168.1.0/24 into /30 you cannot use 192.168.1.0-3 you have to start with 192.168.1.4/30 network; if you were to break it into /25 you cannot use 192.168.1.0-127 you have to start with 192.168.1.128/25 network


You are correct on how the ip subnet zero commands work (ip subnet zero allows the 0 subnet to be used)

Ltat42a

beginner_ccna wrote: »

thanks for the info

so to confirm, if ip subnet zero was configured, i could use the 192.168.0.0/24 starting at the 192.168.0.0-192.168.0.255 range?

if there was no ip subnet configured, then we would start at 192.168.1.0 subnet?

Yes...you are correct.