ip address

[dave dave]

hi! i;ve been assigned an

ip range of 10.10.18.x/24 to be used. I'm thinking of dividing the IPs into the ranges below with one vlan in each segment, but for now i only need to use the 10.10.18.192/27, the rest will only be use in the future. Can i just configure a vlan in an L3 switch and use that 10.10.18.192/27 segment only? or it must start from 10.10.18.0/25? Will there be any issue later? is there any best pratices for using and dividing thes IP ranges? Thanks.

Network               Host Range

10.10.18.0/25      10.10.18.1-126
10.10.18.128/26  10.10.18.129-190
10.10.18.192/27  10.10.18.193-222
10.10.18.224/27  10.10.18.225-254

[thiland · Accepted solution]

No, there is no requirement to start at the beginning of a network range (e.g., 10.10.18.0/25 in your case).

In a given IP scheme there many variables to consider.  If there are no restrictions I prefer to use a /24 mask for every segment since that is a common and well understood mask.  It also prevents IT staff from having to remember a bunch of different masks, which tens to confuse things.

Another advantage is that you can match your VLAN ID with the 3rd octet in your subnet (10.10.18.0/24 is VLAN 18, etc.)

For the 10.10.18.192/27 segment in your case, you could do something like:

10.10.18.193     L3 SVI gateway IP (future HSRP VIP)

10.10.18.194     Reserved for primary gateway (HSRP physical)

10.10.18.195     Reserved for standby gateway (HSRP physical)

10.10.18.196-222     Everything else