Having Problem Advertising IP Range on the Internet

[ahmed-ejaz]

Dear Experts,

I am advertising an IP range 175.106.20.0/20 on the Internet for my company. I would like to divide this range into smaller chunks to easily manage it. Please advice any software or a utility which can give me the exact mask as well as the chunk ranges to advertise.

Thank You.

[John Peek]

They are called subnet calculator's. I would recommend googling for one. There are plenty of free ones out there on the internet. I would try looking for the one that best fits your purpose.

[Jon Marshall · Accepted solution]

Just to add to John's post.

Subnet calculators are useful for working out ranges with a specific subnet mask applied but it is really up to you to decide how you want to break it down ie.  175.106.20.0 255.255.240.0 could be subnetted in many ways to give many different individual subnets so you need to start with an idea of how many subnets you need and how many hosts per subnet you need.

Bear in mind also that there are limits on how small a range can be advertised to the internet.

Jon

[ahmed-ejaz]

Thank you for your reply.

Kind regards.

[JORGE RODRIGUEZ · Accepted solution]

Adding to Jon,  that single /20 block  is a huge block   , you could brake  for example to  16     /24 networks,  254 ip host per /24 network.

Example :

175.106.16.0/24
172.106.17.0/24
x.x.18.x/24
x.x.19.x/24
x.x.20.x/24
x.x.21.x/24

and so on...

The key to keep in mind  is  how you would want these blocks be announce,  I suggest you do thorough analysis  of your company internet architecture , present and future and come  up with proper  allocation of your blocks to minimize the re-addressing and re-advertizing nightmares.     

another example could be out of a /24 off your /20 block say 175.106.18.0/24  can be  further brake  down to smaller blocks to be announced in various sites , again , like Jon indicated in his post, it all depends on your company's requirements for example such as branch offices having their own internet ISP where you may have public web servers  requiring public IP addresses, or even requiring public IP pool blocks  for various purposes etc.. 

Another example of further braking  down your /24  you can have two /26's off that 175.106.18.0/24 that is still part of the /20 network , which could be 175.106.18.0/25 and 175.106.18.128/25 allowing 126 public IP addresses per network , and have these blocks being announced by  different  office branches  that have their own ISP , this is just an example , or announce both and separate  the routing at the perimeter device, there are so many variables in allocating and braking down that huge /20 block.

Here is a freeware subnet cal if you are still looking for one.

http://www.solarwinds.com/register/registration.aspx?program=92&c=70150000000CcHV&INTCMP=DLIndexA_FreeTools_freeSubnetCalculator

my 2 censt

Regards

[Julio Garcia · Accepted solution]

how many breakout points to the Internet do you have?

when advertising to the internet -- i recommend you advertise the whole range /20  (via BGP) to your transit provider.

Internally you should use an IGP  and split (and do whatever you want)  without affecting your global internet route.

[ahmed-ejaz]

Thank you all, it has been sorted out.

Kind Regards,

Ahmed Ejaz