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RFC 872 September 1982
M82-48
TCP protocol on the LAN
(RFC872 TCP-ON-A-LAN)
M.a. Padlipsky
The Mitre Corporation
Bedford, Massachusetts
One: Summary
In this document, we prove that those TCP and IP protocols that consider DOD (US Department of Defense) standards
The viewpoint of the General Area Network is incorrect. This document is closely related to M82-47, M82-49, M82-50, And M82-51.
of.
2: The main purpose
The main purpose of this paper is to negate that the TCP protocol is used in the LAN for a WOOZLE. To achieve
At this point, we need to know what is woozle, what is LAN, what is TCP.
1: Woozles (a terrible animal)
The first question is quite simple [1]:
A sunny winter day, Piglet is swepting the snow in front of its family. He suddenly found that Pooh is in the wind circle, it seems to be
What is the problem. So Piglet said to him: "
"Hey, what are you doing?"
"Hunt."
"What is hunted?"
"Tracking puzzles." Pooh mysteriously said.
"What is a problem?"
"This is what I am thinking, what is I followed?"
"Do you think there is an answer?"
"Not yet. See that." Pooh pointed at the ground in front of it: "What is it?"
"Snow, animal claws" Piglet excited screams, ", don't you think this is a woozle!"
So they are mutually believed in this is a WOOZLE, a terrible animal. They are afraid, until
Christopher Robin tells them that they are just their own footprints.
In fact, this is like we are afraid that the TCP protocol is used in a local area network. We misunderstand the agreement and the environment, the non-technical
Not allowed in operation.
2: LAN
The second question is not that simple. In general, the LAN is a short distance (km), high transmission rate (greater than
Hundreds of kbps), low-error rate communication mechanism (subnet). It first makes it possible to communicate between computer (host), second, allowing network
The printer and TCP protocol terminal communicate with the host, although this is not necessary.
In this way, in principle, the host is heterogeneous. They are not overlapping in the same operating system. In order to achieve ArpaNet
"Resource Sharing" and ISO are called "open system interconnect" targets, and communication between hosts through hierarchical protocol. Communication method
It is the host to the host (point-to-point) or broadcast mode. (In some special environments, such as Ethernet, the attractive way is broadcast;
Other environments, such as ARPA- and ISO-standard "Internet", broadcast ways so expensive, it is not possible to be
achieve.)
For the realization of the local area network, we did not make any assumptions. Local area network media may be twisted pair, CATV,
Coaxial cable, fiber, etc. If the medium uses the processor to the processor bus, then this system is more like distributed multi-operating system.
The microprocessor cannot be used in ARPANET or ISO level agreement. Like "PDSC" (The Pacific Data Service Center)
And the "NMIC" system is not a local area network. The topology of the LAN may be bus, ring network, or star. From this point, digital PBX is a local area network, because
For its transport medium, it provides resources to share and open interconnections, although it is not guaranteed to guarantee the transmission rate and the error rate. From the topology,
It is a central star structure.
For us, the seductive nature of the LAN is its high data transfer rate and low error rate. Expect, achieve this nature
The transmission medium cannot be used as a TCP protocol designed for a long-distance communication network (we did not attribute the bandwidth waste)
According to Baotou. [2] .pp.1509f, the refutation of the traditional communication method is provided.) If you want to do it, only some terminals are connected
Some hosts, you don't need any network protocol at all, you can only be called LCN, not the LAN we discussed.
3: TCP
The third one we need to know is directly subtle. Rely on our understanding of the ArpaNet standard protocol: intuitive
It's up to say that Figure 1 and figure 2 need to express it, which means that the Arpanet standard agreement is not a whole.
But hierarchical. In order to explain this problem, we believe that the TCP protocol is a host to host protocol (approximate
Equivalent to the fifth layer of the ISO standard protocol). Its most significant nature is to provide a reliable logical connection. (This is slightly
It will be mentioned.) Another significant nature of the TCP protocol protocol is designed for CateNet (or an Internet),
That is to say, between the hosts connected to different communication subnets can communicate the .TCP protocol in the hosts on the Catenet
Its nature, like data stream control, logical connection management, etc. is easy to design.
Because the unique address mechanism of the TCP protocol (that is, it uses two-dimensional overall "to represent the external host address because it does not
Know if the host is on the same subnet), it requires an interface (IP protocol) to handle information from different subnets. This connection
The mouth is an IP protocol. Although the IP protocol protocol is designed to be independent of the TCP protocol protocol, it is a data transfer between the main unit.
Founded.
In order to deal with different subnet issues, the IP protocol has the following nature: IP protocol checks a preservation with a host
The table of the recent subnet (such as priority, service level, security tag), which determines that an Internet address is here
On the net; if so, it sends the information to this subnet, otherwise it sends information to the gateway (it has another IP protocol
Module). Visible, IP Protocol Protocol Processes Internet Routing, while TCP Protocols handle Internet addressing. Because some subnet transmission
Poor ability, can only transfer small data packets, IP protocol protocols should also split large data packets into the size of the corresponding subnet. Most
The IP protocol protocol should provide a mechanism that can be identified by other protocols. (This is achieved by hierarchical principles:
You don't need to understand the data transmitted by the IP protocol, just know what IP protocol is going to do.)
It seems to have a bit of trouble, because there are too many mechanisms. (More complete discussion, clear references [4]). But these are already
Enough to prove our point of view. An unapproved protocol is a UDP protocol ----- User Data News Agreement .udp protocol is more powerful
The rate is not the right rate, it is unreliable. For the UDP protocol protocol, any packet creates a logical connection.
Pick up .. This way, if you want multiple channels to transfer data, you should use the UDP protocol instead of the TCP protocol.
Three: TCP protocols on the LAN
Regardless of whether your host belongs to a local area network, no matter whether you understand the TCP / IP protocol, if you want to be with the Internet
Another host communication, you must use the TCP protocol. If you want to do some network applications (on the ISO standard protocol)
Part 5's part of the services and all of the tops 6th, 7th, as needed to TCP / IP protocol because it provides reliability through logical connections.
Data stream control, order control, etc. If your application does not require the nature of the TCP protocol, don't use it, no matter you
What is it? If you want to communicate with the host on the same network, you can design an agreement yourself, but this is usually extremely
It is bad. If you want your network to maintain a natural state, the TCP / IP protocol will not hinder you at all. But you should remind you,
Your application requires the host's protocol to the host, so unless you want to engage a true parallel thing ... Otherwise, the main unit
The protocol is essential.
Now I have to discuss performance issues. This is a very detailed question. It should be pointed out: before considering reliability
Taken, many people (including me) are treated to the TCP protocol. Because research institutions have experiments on many types of mainframes show:
Although the TCP protocol protocol is friendly, it is only 12% efficiency. This makes us consideration and there is no need to change a host to the host's protocol to replace the TCP protocol. (If there is such an agreement, it should also have Reliability of TCP Protocol Agreement
This advantage. Because you are doing TCP protocols, not LCN, just mentioned before.)
Catch this woozle!
Four: Other properties
Other properties of TCP / IP will be explained below:
1. TCP / IP can be used between two completely different operating systems;
2. TCP / IP has been applied for several years;
3. The IP layer does not limit the interface protocol provided by the subnet (although some of them are a waste);
4. The IP layer does not limit its users, as long as the subnet provides routing (unlike X.25);
5. The gateway of the IP protocol also has properties of 3 and 4;
6. TCP / IP meets the DOD standard;
7. Application protocols and file transfer protocols (including email) already exist and used in many different operating systems
on;
8. TCP / IP is supported by the US Department of Defense Agreement;
9. The latest data reported by the research institution is:
Subnet
Subnet
Phone line
Actual value (kb / s)
300
1.2K
9.2
Theoretical value (kb / s)
800
9.2k
9.6
Because of the nature 8, there is no other protocol than TCP / IP. Special pay special attention to the above nature should not be misunderstood as a local area network
A limit on performance analysis of the TCP / IP protocol. (But you should know the difficulties of performance analysis in the local area network: 1.
The selection protocol is more difficult; 2. Most hosts cannot produce the high data generating rate as you envisage.) This is like a limit
The use of TCP / IP protocols.
Five: Other useful data
Here, we have already discussed the problem, but further analyzing the performance of the host is reasonable. If you just want to get
The previous discussion. The host terminal is a refresh mode, and each screen is 16ms. So how many times is interrupted 1 second? I
We know that the hard disk finding time is 17ms, the data is extracted from the hard disk to 2ms, if the data is transferred to the network, there is 1 ms, then
Add up to 20ms, although the host has nothing. If the I / O rate of the local hard disk is 16kb, then 1 second, the host only
Can provide 50-screen / second refresh rate, approximately 800kb / s, this rate meets the rate of TCP protocol (see nature 9). In an actual
In the system, the host does not meet this rate. (The analysis of the host data transfer rate is difficult because it relies on the system
The internal performance. Because of the essence of the classic operating system, if the needs of shared stacks between processes, the input data occupies the needs of memory.
It is impossible to get the data transfer rate than the transmission rate you can generate.)
Six: Conclusion:
It is considered that the TCP protocol agreement cannot be used for the LAN, which is not available .TCP protocol agreement
For the local area network, the communication between the host is implemented.
Seven: References
[1] Milne, A. A., "Winnie-The-Pooh", Various Publishers.
[2] The lan description is based on Clark, D. D. et al., "AN
Introduction to Local Area Networks, "IEEE Proc., V. 66, N.
11, November 1978, PP. 1497-1517, Several Year's Worth of
Conversations with Dr. Clark, and The Author's Observations
Of Both the Open Litrate and The Oral Tradition (Which
Were Sufficiently Well-Thought of to Have Prompted The Mitre
Corporation / NBS / NSA Local Nets "Brain Picking Panel" to have
Solicited His Testimony During The Year HE Was in Facc's
EMPLOY. *)
[3] The TCP / IP DESCRIPTIONS Are Based on Postel, J. B.,
"Internet Protocol Specification", "Transmission Controlspecification" in Darpa Internet Program Protocol
Specifications, USC Information Sciences Institute,
September, 1981, And ON More Than 10 Years' Worth of
Conversations with Dr. Postel, Dr. Clark (now Darpa
"Internet Architect") and Dr. Vinton G. Cerf (Co-Originator
Of TCP), And ON Numerous Discussions with Several Other
MEMBERS of the TCP / IP Design Team, on Having Edited THE
Referenced Documents for the PSTP, AND, For That Matter, ON
Having Been One of the Developers of the arpanet "Reference
"MODEL."
[4] Padlipsky, M. A., "a atpective on the arPanet Reference
Model ", M82-47, The Mitre Corporation, September 1982; Also
Available in proc. infocom '83.
_________________
* In All Honesty, AS Far As I Know I Started The Rumor That TCP
Might Be overkill for a lan at what meetings. at the next tcp
Design Meeting, HoWever, They Separated IP Out from TCP, AND
Everything's BEEN Alright for About Three Years now - Except
For getting the rumor killed. (i'd Worry About Woozles
Turning Into Roosting Chickens if it beches
That: 1. People Tend to Ignore Their Local Guru; 2. I WAS
Trying to Encourage The IP Separation; and 3. All i Ever
Wanted Was Some Empirical Data.)
NOTE: Figure 1. ARM in the Abstract, And Figure 2. ARMS,
Somewhat particularized, may be obtained by Writing to: mike
Padlipsky, Mitre Corporation, P.O. Box 208, Bedford,
Massachusetts, 01730, or sending computer mail
Padlipsky @ USC-ISIA.
RFC872 TCP protocol on the local area online TCP-ON-A-LAN
1
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