So, in your case it's:

0 00000000

1 00000001

2 00000010

3 00000011

So, you take 6 bits plus the other 16 and you get the /22.

I think supernetting and summarization are the same thing - summarizing networks by creating a supernet.

Solved

Posted on 2005-04-28

Is the following an example of manual route summarization. Or is it an example of supernetting?

ps: If ripv2 or EIGRP were to summarize this route, it would advertise it as 192.168.1.0/24 right

192.168.0.0/24

192.168.1.0/24

ROUTER-------192.168.0.0/22----------------->

192.168.2.0/24

192.168.3.0/24

thanks

ps: If ripv2 or EIGRP were to summarize this route, it would advertise it as 192.168.1.0/24 right

192.168.0.0/24

192.168.1.0/24

ROUTER-------192.168.0.0/2

192.168.2.0/24

192.168.3.0/24

thanks

6 Comments

So, in your case it's:

0 00000000

1 00000001

2 00000010

3 00000011

So, you take 6 bits plus the other 16 and you get the /22.

I think supernetting and summarization are the same thing - summarizing networks by creating a supernet.

1. So I put the octet of interest in binary, and compare. I find where they are similar.

2. I count the number of bits that are similar (6 bits in our above example).

3. Where do I go from here? Where did the "16" come from?

Supernetting = using fewer mask bits than the "standard" classful mask to expand a network. For example, take a standard class C address, 192.168.0.0 /24. Start running out of addresses and so instead of /24, you use /23 which just doubled your available hosts. That is supernetting. Problem is that not all TCP/IP stacks will recognize anything less than a standard classful mask. Many old printers, etc..

Route summarization is just that, a summary of routes available through you. In your example, you know/have/own 4 Class C subnets and you broadcast to your next hop neighbor a single entry with /22 mask instead of 4 individual /24 entries. Since this is nothing more complicated than a route decision, little intelligence involved. Here, classful boundaries have no meaning. Consider these route entries:

Any and all of them can be used as route summaries, only the Class C could be considered a supernet, if you must label it anything other than what it is - a route summay...

172.16.0.0 /22

192.168.0.0 /22

10.10.0.0 /22

lrmoore:

whats the easiest way to manually summarize?

I got halfway with pseudocyber's method and got stuck.

Convert to binary, find what matches etc...

0 00000000

1 00000001

2 00000010

3 00000011

I understand where the 6 bits came from. But how did we get a /22 mask from this?

Thanks

Supernetting is the opposite of subnetting. So, you can say to yourself, suppose I move the subnet bits some to the LEFT - then would the subnets I have fit inside the supernet I've created.

So, if you have 192.168.1.0 you could subnet it into two with 192.168.1.0/25 and 192.168.1.128/25 right, then, in effect, you could summarize those two with the first network IP - 192.168.1.0/24 (because the range of hosts encompases your two subnets).

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