# Route Summarization

Kelvin Wang
Posts:

**11**Member ■□□□□□□□□□
in CCNP

Hi, can anyone explain to me how to solve the following question? I encounter this question in the ciscopress self study book but am stuck. Your help would be much appreciated, thanks!

Your company is assigned four Class C networks:

200.39.32.0/24

200.39.33.0/24

200.39.34.0/24

200.39.35.0/24

Can these network be summarized into one route advertisement? How?

Your company is assigned four Class C networks:

200.39.32.0/24

200.39.33.0/24

200.39.34.0/24

200.39.35.0/24

Can these network be summarized into one route advertisement? How?

0

## Comments

1,745MemberYes, use a /22 mask.

Edit: I'm sorry.

Well, you need to summarize 4 contiguous networks. So, you need a mask that gives you a block size of 4.0 (or, at least, that's my initial hypothesis)

First, you check if that first number is a multiple of 4.0 or not. if not, then you'd have to go up to 8.0.

Since it is a multiple of 4, then you know you can use the mask of 255.255.252.0.

the network is 200.39.32.0

broadcast is 200.39.35.255

first valid host is 200.39.32.1

last valid host is 200.39.35.254

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1,745Member200.39.33.0/24

200.39.34.0/24

200.39.35.0/24

200.39.36.0/24

And asked you to summarize it to the best of your ability, what would you do?

Well, you could take two approaches

Approach 1: give them exactly what they asked for, summarized as much as possible:

200.39.33.0/24

200.39.34.0/23

200.39.36.0/24

Approach2: If they say to use the smallest possible mask that covers all of the networks given in a single line, then you use this:

200.39.32.0/21

Problems like this illustrate why you should give out network assignments according to binary boundaries

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1,745MemberIf you could show how you are attempting to solve the problem, we could then assist you. I thought route summarization was a CCNA topic?

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104MemberRoute summarization is a CCNP topic, not CCNA. It is helpful to know, and is something that you should know moving forward in the networking field. Don't worry about knowing it 100% for the CCNA.

104MemberWell, just saw this on the CCNA topics:

11Member ■□□□□□□□□□hi Instant000, thanks for the explanation. Sorry but i have got no clue on how to attempt the qs therefore not able to provide how i attempt it. Anyway just another clarifications, the first number we talk about here is 32? Which is a multiple of 4. But i dont really get the mask, how does it link to [URL="tel:255.255.252.0"]255.255.252.0[/URL]? Is it because 252(dec) = [URL="tel:11111100"]11111100[/URL](bin) and we use the host bit 2^2 which gives 4?

11Member ■□□□□□□□□□Thanks for the clarification sir. Yes indeed. i have passed my ccna, but somehow i am still unclear about this topic.