Consult a CIDR problem-CodePudding

Recently in Xie Xiren "computer network" fifth edition, read CIDR part, is 137 and 136 in the book,
The author mentions "without using CIDR, in 1994 and 1995, a routing table of the Internet will be more than 70000 projects, and after using the CIDR, in 1996 a number of routing table was only more than 30000",
The meaning of this passage is CIDR sharply reduced the number of routing table project, could you tell me what this mean?

My understanding is that the original routing table to write down each subnet network number, now only need to write a CIDR network number,
But, this how to implement?

For example, a router R1, connected to the R2, the export of R2 1 has three subnet 172.30.1.0, 172.30.2.0, 172.30.3.0
Original routing table wrote three subnet network number, use the CIDR, write a 172.30.0.0?

There is a problem, divided into subnets, must be the same interface is connected to the router?

CodePudding user response:

refer to the original poster vayrrr response:

recently watching Xie Xiren "computer network" fifth edition, read the CIDR section, is 137 and 136 in the book,
The author mentions "without using CIDR, in 1994 and 1995, a routing table of the Internet will be more than 70000 projects, and after using the CIDR, in 1996 a number of routing table was only more than 30000",
The meaning of this passage is CIDR sharply reduced the number of routing table project, could you tell me what this mean?

My understanding is that the original routing table to write down each subnet network number, now only need to write a CIDR network number,
But, this how to implement?

For example, a router R1, connected to the R2, the export of R2 1 has three subnet 172.30.1.0, 172.30.2.0, 172.30.3.0
Original routing table wrote three subnet network number, use the CIDR, write a 172.30.0.0?

There is a problem, divided into subnets, must be the same interface is connected to the router?

To the first question, which is in accordance with your understanding, but should pay attention to use the CIDR subnet mask will be smaller after polymerization, the second question, each of the router interface is a network segment

CodePudding user response:

What's that mean

CodePudding user response:

Division of the subnet, belongs to different network segments, different interfaces need to be configured on the router, but a router interface can be configured to more child interface, each interface is equivalent to a router interface on logic, but physically, it just use the a interface of the router, that is, an interface on the router configuration can be different the IP address of the network segment

CodePudding user response:

Hello, to the first question to you, that the above three 172 class C network segment, the subnet mask is 24, super net, forward network, looking for the same position, should be to shift to the left two, then the book behind the content such as you will see in the static routing routing summary about the related introduction, the other is that the content, if you have any doubt you read a book, give you recommend a teacher speak of, is according to Xie Xiren teacher speaking of this book, I was listening to the teacher before, very detailed, oneself to go B station search Han Ligang
https://www.bilibili.com/video/BV17p411f7ZZ? The from=search& Seid=10729750600823930991

CodePudding user response:

The third paragraph is 1-3, keep the third paragraph 2 host a bit, the third section is divided into network is 6-64, 172.30.0.0/22, network address 172.30.0.0, legal address 172.30.0.1 to 172.30.3.254 went,