TCP vs UDP - Explaining Facts and Debunking Myths - TCP Masterclass

Summary

In this educational video, Ed Harmush delves into the core differences between TCP and UDP, two fundamental layer 4 protocols of the internet. He clarifies misconceptions, explains the concepts of connection orientation, reliability, flow control, and overhead, and dispels myths like the speed and security of the protocols. The video serves as a foundational guide for understanding the intricacies of TCP's features and UDP's straightforward approach to data transmission.

Takeaways

• 🔌 TCP and UDP are both Layer 4 protocols that have been essential to the internet for around 40 years.
• 🔗 TCP is connection-oriented, requiring an official start and end to a connection, unlike UDP which does not.
• 📥 TCP provides reliable service with confirmation of data delivery, while UDP does not confirm whether data has been received.
• 🔄 TCP ensures data is delivered in the correct order with sequence numbers, whereas UDP does not guarantee order and leaves it to the application.
• 💧 TCP offers flow control to manage data transmission rates based on available bandwidth, but UDP transmits data as fast as possible.
• 🚫 The term 'UDP is faster' is a myth; latency is the same for both protocols and 'faster' likely refers to UDP's less overhead.
• 🛡️ Contrary to a common myth, TCP does not provide more security; both protocols are equally insecure without additional security measures.
• ❌ The statement 'UDP is unreliable' is a myth; UDP doesn't provide reliability features at Layer 4 but doesn't make data less likely to arrive.
• 🚫 Saying 'TCP provides guaranteed delivery' is a myth; TCP can only confirm delivery, not ensure it.
• 📊 TCP headers are larger due to additional features like sequence numbers and acknowledgment numbers, adding more overhead compared to UDP.
• 📚 Understanding the four major differences and myths about TCP and UDP is crucial for anyone looking to deepen their knowledge of networking protocols.

Q & A

What are the two primary protocols discussed in the video?

The two primary protocols discussed in the video are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), both of which are layer 4 protocols in the OSI model.

What does the term 'service to service delivery' refer to in the context of TCP and UDP?

In the context of TCP and UDP, 'service to service delivery' refers to the process of multiplexing and demultiplexing of traffic, which is the technical term for the main purpose of these protocols to deliver data from one service to another.

What are the four dimensions in which TCP and UDP are compared in the video?

The four dimensions in which TCP and UDP are compared are connection orientation, reliability, flow control, and overhead.

What is the main difference between TCP being connection-oriented and UDP not being connection-oriented?

The main difference is that TCP has an official start and end to a connection, requiring a special packet to initiate and another to terminate the connection, while UDP does not have an official start or end and simply sends data onto the wire without such signaling.

How does TCP provide reliability in terms of data delivery?

TCP provides reliability by offering confirmation of data delivered through acknowledgments, ensuring that the sending host knows when data has reached the receiving host. UDP does not provide such confirmations.

What does it mean for TCP to provide 'informed delivery'?

Informed delivery in TCP means that the protocol provides confirmations when data is successfully delivered, allowing the sender to be aware of the data's arrival at the receiver, which UDP does not offer.

How does TCP ensure the correct order of data delivery to the application?

TCP ensures the correct order of data delivery by labeling packets with a sequence number, which allows the receiver to reorder packets if they arrive out of sequence before handing them to the application.

What is flow control and how does TCP provide it?

Flow control is the regulation of data transmission to prevent data loss by adjusting the rate of transmission based on the available bandwidth. TCP dynamically adjusts its transmission rate to use the maximum available bandwidth without exceeding it, unlike UDP which transmits data as fast as possible.

What is the difference in overhead between TCP and UDP?

The difference in overhead is the size of the header each protocol adds to the data. TCP adds a larger header with more information to support its features, while UDP adds a smaller header with fewer fields.

What are some common myths about TCP and UDP that the video aims to dispel?

The video aims to dispel myths such as UDP being faster, TCP being more secure, UDP being unreliable, and TCP providing guaranteed delivery. These myths are clarified with explanations that highlight the actual functionalities and characteristics of the protocols.

Why does the instructor dislike the phrase 'TCP is more secure'?

The instructor dislikes the phrase 'TCP is more secure' because it is misleading. Neither TCP nor UDP provides inherent security features at the transport layer. Security measures must be applied at other layers, such as using IPSec, SSL/TLS, or SSH.

What does the instructor suggest is a better way to describe the reliability of UDP compared to TCP?

The instructor suggests that a better way to describe it is to say that UDP doesn't provide reliability features at layer 4, rather than labeling it as 'unreliable'. This is because the actual odds of packet delivery over the network are the same for both TCP and UDP; it's the confirmation of delivery that differs.

Why does the instructor dislike the phrase 'TCP provides guaranteed delivery'?

The instructor dislikes this phrase because it implies that TCP can ensure packets will always reach their destination, which is not true. TCP provides acknowledgments and can retransmit lost packets, but it cannot guarantee delivery if there are physical issues with the network connection.

Outlines

00:00

🔌 Introduction to TCP and UDP

This paragraph introduces the topic of TCP (Transmission Control Protocol) and UDP (User Datagram Protocol), two fundamental layer 4 protocols that have been pivotal to the internet's operation for decades. The video aims to provide a comprehensive understanding of these protocols, starting with clarifying what they are and are not. The presenter, Ed Harmush, references previous discussions on the OSI model and service to service delivery, and sets the stage for a series that will delve into the specifics of TCP. The focus is on establishing a foundational understanding before exploring TCP's depth, and viewers are directed to previous content for background information.

05:00

🔗 Connection-Oriented vs. Connectionless Communication

The second paragraph delves into the distinction between TCP being connection-oriented and UDP being connectionless. It explains that TCP requires an official start and end to a connection, involving a handshake process where hosts communicate their readiness to send and receive data. This is contrasted with UDP, which does not have a formal connection setup or termination; data is simply sent without such signaling. The paragraph also discusses how UDP 'connections' are conceptualized based on shared attributes like IP addresses and port numbers within a certain time frame, rather than through official connection signals.

10:01

📥 Reliability and Data Delivery Confirmation

This section examines the concept of reliability in TCP, which is broken down into three subparts. Firstly, TCP provides confirmation of data delivery, meaning that an acknowledgment is sent by the receiving host, allowing the sender to know the data has arrived. UDP lacks this feature, offering no guarantee or acknowledgment of delivery. Secondly, if data is not delivered over TCP, the sender is informed of the transmission error, which can be communicated to the application for user notification. UDP does not provide this error notification at the transport layer. Lastly, TCP ensures data is delivered in the correct order by using sequence numbers, which is crucial given the potential for packets to take different paths across the internet. UDP does not guarantee order, leaving it to the application to manage if necessary.

15:04

💧 Flow Control and Bandwidth Management

The fourth paragraph discusses the flow control mechanisms of TCP, which adjusts the transmission rate to match the available bandwidth without data loss, in contrast to UDP's approach of transmitting data as quickly as possible. This can lead to packet loss with UDP when the network path's bandwidth varies. TCP dynamically adjusts to the lowest bandwidth available across the entire path, ensuring efficient use of bandwidth and minimizing packet drops. The paragraph illustrates how TCP starts with a conservative transmission rate and increases it while monitoring for packet loss, adjusting accordingly to maintain optimal transmission without exceeding the available bandwidth.

20:04

📤 Overhead Comparison: TCP vs. UDP

This paragraph compares the overhead of TCP and UDP, focusing on the size of the headers added to data packets. The UDP header is minimal, consisting of source and destination ports, a length field, and an optional checksum, totaling only eight bytes. In contrast, the TCP header is significantly larger, with a minimum of 20 bytes and potentially expanding up to 60 bytes with options. The larger TCP header is necessary due to the additional features TCP provides, such as sequence and acknowledgment numbers, control flags, window size, and a mandatory checksum. The concept of 'more overhead' versus 'less overhead' is clarified, highlighting the trade-offs between TCP's reliability and control features and UDP's simplicity and lower overhead.

🛡️ Debunking Myths About TCP and UDP

The final paragraph addresses and dispels four common myths about TCP and UDP. The first myth, that UDP is faster, is clarified by explaining that latency is unaffected by the protocol used; 'faster' in this context likely refers to UDP's lower overhead. The second myth, that TCP is more secure, is refuted by stating that neither protocol provides inherent security; security must be implemented at other layers. The third myth, that UDP is unreliable, is nuanced by explaining that while UDP does not provide reliability features at layer 4, it does not inherently make it unreliable, as reliability can be managed by the application. Lastly, the myth that TCP provides guaranteed delivery is corrected to clarify that TCP offers acknowledgment of delivery but cannot ensure delivery in the face of network issues; it can only inform of delivery status.

🎬 Conclusion and Future Lessons

In conclusion, the video outlines the main takeaways, which include understanding the four major differences between TCP and UDP and the myths surrounding them. The presenter expresses a desire to continue the series in-depth, covering additional TCP features such as flags, sliding windows, checksum calculations, flow control algorithms, and TCP options. However, the continuation of the series is contingent upon viewer engagement, urging viewers to like, comment, subscribe, and share the video to ensure its visibility and the production of further content.

Keywords

💡TCP

TCP, or Transmission Control Protocol, is a core protocol of the Internet Protocol Suite. It is connection-oriented, meaning it requires a handshake process to establish a connection before data can be transferred and a termination process after the data is sent. TCP ensures reliable data transmission by confirming the delivery of packets and correcting any errors. In the script, TCP is described in detail, including its features like reliability and flow control.

💡UDP

UDP, or User Datagram Protocol, is another core protocol of the Internet Protocol Suite, but unlike TCP, it is connectionless. This means that data can be sent without establishing a connection, making it faster but less reliable. UDP does not confirm data delivery or correct errors, which can lead to data loss. The script explains that UDP transmits data without an official start or end to the connection and does not ensure data order or reliability.

💡Connection-oriented

A connection-oriented protocol, like TCP, establishes a connection before transmitting data and ensures that the connection is properly terminated after the data is sent. This involves a handshake process at the beginning and an acknowledgment process for each packet sent. The script uses the term to explain one of the fundamental differences between TCP (connection-oriented) and UDP (not connection-oriented).

💡Reliable

Reliability in networking refers to the guarantee that data is delivered accurately and in the correct order. TCP is considered reliable because it confirms the receipt of data packets and ensures that any lost or out-of-order packets are retransmitted. The script explains that TCP's reliability includes confirmation of data delivery, error notification, and correct data ordering, in contrast to UDP's lack of these features.

💡Multiplexing and Demultiplexing

Multiplexing is the process of combining multiple signals or data streams into one, while demultiplexing is the reverse process, separating a combined signal back into individual streams. TCP and UDP use these processes to manage data streams between applications and the network. The script mentions these concepts to explain how TCP and UDP handle service-to-service delivery.

💡Flow Control

Flow control is a feature of TCP that adjusts the rate of data transmission based on the network's capacity to prevent congestion and packet loss. TCP dynamically adjusts its transmission rate to use the available bandwidth efficiently. The script contrasts this with UDP, which sends data as fast as possible without considering network capacity, leading to potential data loss.

💡Overhead

Overhead refers to the additional data (headers) added to a packet to manage and control the data transmission process. TCP has more overhead than UDP because it includes extra fields in its header to ensure reliability, flow control, and other features. The script explains the difference in overhead between TCP (20-60 bytes) and UDP (8 bytes) and how this impacts their performance.

💡Latency

Latency is the time it takes for a data packet to travel from the source to the destination. The script dispels the myth that UDP is faster than TCP by explaining that the transmission speed (latency) is identical for both protocols; what differs is the overhead and reliability features, not the inherent speed of packet delivery.

💡Checksum

A checksum is a value used to verify the integrity of a data packet. TCP includes a mandatory checksum in its header to ensure that data is not corrupted during transmission. UDP also has a checksum, but it is optional. The script mentions checksums when comparing the headers of TCP and UDP and their roles in data integrity.

💡Sequence Number

A sequence number is a part of the TCP header used to ensure that data packets are delivered in the correct order. Each packet is assigned a sequence number, allowing the receiving host to reassemble the data in the correct order, even if packets arrive out of sequence. The script explains how TCP uses sequence numbers to provide reliable data delivery, unlike UDP, which does not use sequence numbers.

Highlights

Introduction to TCP and UDP as the workhorses of the internet for the last 40 years.

Exploration of TCP and UDP within the context of the OSI model and their roles in service to service delivery.

Clarification of the terms 'connection-oriented' and 'not connection-oriented' in relation to TCP and UDP.

Explanation of the process of establishing a TCP connection through special packets.

UDP's approach to data transmission without an official connection start or end.

The concept of defining a UDP connection based on timeout and packet attributes.

TCP's reliability through confirmation of data delivery and acknowledgments.

UDP's lack of data delivery confirmation and its implications for error awareness.

The importance of sequence numbers in ensuring the correct order of TCP data delivery.

UDP's lack of intrinsic data ordering and its impact on application-level handling.

TCP's flow control mechanism to dynamically adjust transmission rates based on available bandwidth.

UDP's approach to transmit data as fast as possible without adjusting to bandwidth variations.

The overhead comparison between TCP and UDP, with TCP adding a larger header to data payloads.

Debate on the myth that UDP is faster due to less overhead, and the clarification on latency.

Dispelling the myth that TCP is more secure, emphasizing that neither protocol provides inherent security.

Clarification on the myth that UDP is unreliable, explaining the actual meaning of reliability in protocols.

Debate on the phrase 'TCP provides guaranteed delivery,' explaining the limits of TCP's reliability.

Invitation to the audience to engage with the content for further exploration of TCP's features.

Transcripts

it's time to explore TCP and UDP in the

true practical networking style get

ready to really understand how and why

these two layer 4 protocols have been

the workhorses of the internet for the

better part of the last 40 years

[Music]

hello everyone my name is Ed harmush and

in this video we'll be kicking off what

will likely be a pretty thorough series

on TCP but before we get into the depth

of TCP we have to start on the same page

so in this video we're going to be

covering TCP and UDP specifically we're

going to be talking about what TCP and

UDP are and what they are not

now if you're looking for some

background information before we get

into TCP and UDP we first mentioned the

concepts of TCP and UDP back in our

networking fundamental Series in the

lesson on the OSI model in that lesson I

showed you this slide and I told you

that the main purpose of DCP and UDP is

what I like to call service to Service

delivery the technical term for this is

multiplexing and demultiplexing of

traffic

in any case in that slide I told you

that there are two strategies for how

this is done that's where TCP and UDP

come into play so if you're looking for

some context or background information

I'd point you to this video there'll be

a link in the description

what we're going to do in this video is

unpack TCP or the transmission control

protocol and UDP or the user datagram

protocol across four different

dimensions we'll first start by talking

about four important differences between

TCP and UDP and then I'm going to dispel

four common myths about TCP and UDP that

I keep hearing about

with that said let's get into the first

difference that we're going to be

talking about and that has to do with

TCP being connection oriented and UDP

being not connection oriented now if

you're anything like me when I first

read that about TCP and UDP I had no

idea what they meant it actually took a

few years before I finally understood

what they mean by this and I'd like to

communicate that to you now what they

mean by connection oriented is that

there is an official start and an

official in to a TCP connection

UDP does not have that so what that

means is that before this host can send

TCP data packets to the other host it

first has to send a special packet that

essentially says hey I'd like to start

speaking TCP with you let's start a

connection

and then this host has to respond saying

cool I'm ready to speak and now this

host can actually start sending data

onto the wire

then once that host has finished sending

the data it needs to send it's then

going to send another special packet

indicating that it is now done sending

data on the wire and this host will

respond saying great I've received all

the data I am done with this connection

as well

by comparison UDP does not have an

official start or end to the connection

if this host wants to send UDP data to

that host all it's going to do is simply

put that data onto the wire and hope it

gets to the other side there isn't any

sort of signaling that indicates this is

the start of the UDP connection and this

is the end of a UDP Connection in fact

some people say that there is no such

thing as a UDP connection but in modern

network engineering parlance people

refer to a UDP connection all the time

but if there's no official start or end

how do we determine which set of packets

all belong to the same connection well

with UDP all you can really do is Define

it based upon the timeout any packets

that share the same five double that's

Source IP Source Port destination IP

destination port and protocol in this

case UDP and arrive within the same

certain time period can all be said to

be a part of the same UDP connection

now this timeout is not a constant value

I've seen a lot of different values from

different vendors and different software

two minutes seems to be a pretty common

one but by no means is that a standard

across the internet

in any case that's the first major

difference between TCP and UDP that I

wanted to unpack for you and hopefully

that gives you a much better

understanding of the terms connection

oriented and not connection oriented

than I had when I first started learning

networking which brings us to the second

attribute we're going to discuss

regarding TCP and UDP

the next component that we're going to

discuss about TCP and UDP is that TCP is

said to be reliable but again what do

they actually mean when they say TCP is

reliable well there's actually three

subparts to what is meant by reliable

and I'm going to explore each of them

for you in the next few minutes the

first sub-component of TCP being

reliable is this TCP provides

confirmation of data delivered what that

means is that if this host sends some

data to this host every time this host

receives that data it's going to send an

acknowledgment saying hey I just

received that data this means this host

knows whenever data actually got to the

other side

by comparison UDP does not have that UDP

doesn't provide any sort of confirmation

of data delivery if this host sends UDP

packets of this host it's simply going

to put those packets on the wire and

hope for the best the receiving host

isn't going to do any sort of

confirmation that the data actually got

there

that's the first part of what is meant

by TCP being reliable now the benefit of

this is that if we are confirming every

time data is actually delivered that

means we are aware if something didn't

actually make it through if this host

put TCP packets on the wire and never

receives that confirmation well this

tells this host that something happened

with a transmission

which means this host can then notify

the application which initiated the TCP

connection that some sort of error had

occurred that's useful because then the

application can provide an error message

to the user telling the user that some

sort of error has occurred

UDP doesn't have that since UDP doesn't

have any sort of data delivery

confirmation

UDP is unaware of any errors actually

happen

meaning if this guy sent UDP packets

across the wire and something happened

to those packets this guy is not going

to know anything about it at layer 4.

the application might have their own

confirmation of delivery built into the

application but none of that is provided

by UDP at layer 4. those are the first

two subparts to what is meant by TCP

being reliable the third and final part

of that is this guy with TCP data is

delivered to the application in the

correct order so here's what I mean by

that remember that with typical internet

communication it's not like the host is

directly singing data to another host

instead often it's some sort of

application running on this host is

telling this host to put certain packets

on the wire and send it via TCP or UDP

in the case of TCP any packets that the

application say to send TCP will label

with a particular sequence number for

Simplicity I'm just going with one two

and three this sequence number can then

be used to make sure that on the other

side that data is delivered to the

application in the correct order

now if The Two Hosts are literally

connected via same wire then it doesn't

really matter because the order in which

you put these packets on the wire is the

order in which they'll arrive on the

other side

but often when you're speaking to

another host you're speaking to another

host on the other side of the internet

which means on the other side of a bunch

of different routers whose job it is to

hand those packets off to one another to

deliver them to the final host

the issue is that there is no guarantee

that those packets are going to be

delivered using the same path so what

can sometimes happen is maybe the first

packet takes the fastest path and the

second packet takes the scenic route and

the third packet took the fast pass then

on the other side what you have is the

packets arriving in the order one three

two even though on the sending side they

are sent as one two and three

now in the case of TCP since TCP labeled

these packets with a sequence number TCP

can switch the packets around as

necessary before they actually hand

those packets to the application the key

there is that the other application is

definitely going to receive the data in

the correct order

UDP doesn't have any sort of intrinsic

data ordering which means if the packets

arrive on the other host out of order

and it's a UDP connection the

application is going to have to deal

with that in whatever way makes the most

sense

possibly the application has their own

method of sequencing or alternatively

possibly the application doesn't really

care about the order in which the data

writes for instance if I'm downloading a

100 megabyte file I don't necessarily

care that byte1 gets there before byte

100. as long as all the bytes get there

I'll be happy so that wraps up talking

through the three subparts to what is

meant when people say that TCP is

reliable

notice however I didn't say that UDP was

unreliable we'll talk more about that in

a moment the third major component about

TCP and UDP is that TCP is set to

provide flow control and UDP does not

let's talk about what that actually

means in the case of UDP UDP is going to

transmit its data as fast as it possibly

can

whereas TCP is going to dynamically

adjust its transmission rate to use the

maximum available bandwidth safely

without exceeding it so let me show you

what I mean now if you have a situation

where the host in communication are

speaking across the path with pretty

much consistent bandwidth availability

then this difference really isn't all

that important they both end up

achieving about the same transmission

rate however most of the time when

you're speaking to another host

especially another host on the other

side of the internet the available

bandwidth throughout the path is not

consistent often one side of the path

has more available bandwidth than the

other or more realistically you'd have

higher bandwidth here lower bandwidth

here higher here lower here higher here

or something like that in any case if

you were to map out the bandwidth

available across the entire path in this

illustration you would have something

that looks like this

now with UDP sending data as fast as it

can what would end up happening is this

host would look at its local connection

and be like whoa look at all this

available bandwidth I have I'm going to

send data as fast as I possibly can

according to this available bandwidth

but as you can see we have more

available bandwidth here than we do over

here

so with UDP you'd have a situation that

looks like this

UDP would be sending data super fast

over here but then once it got to this

side a lot of that data would be dropped

since this side cannot support the same

bandwidth transmission rate

TCP however would dynamically adjust the

transmission rate to stay within the

bandwidth across the entire path let me

show you with TCP you would have

something that looks more like this TCP

would start out low and then start

increasing the bandwidth but once you

start noticing that certain packets are

dropped it would start to adjust its

bandwidth down to whatever is available

for the entire path

then TCP would bounce around at that Max

available bandwidth

now the details of that are rather

interesting and we can get into how all

that works later on in this series

but for now I just want to highlight the

significant difference between flow

control and how TCP will smartly use the

available bandwidth without dropping

packets whereas UDP will transmit

everything as fast as it possibly can

that's what people mean when they say

that TCP provides flow control

and that takes care of our third major

comparison point between TCP and UDP

which brings us to our fourth and our

fourth is that TCP is more overhead and

UDP is less overhead well to understand

this one we have to pull back something

we learned about the OSI model remember

in our lesson on the OSI model we said

that the application layers layer 5 6

and 7 are going to put together some

sort of data that should be sent to the

other side

the application layers are then going to

hand that data to layer 4. and layer 4

is going to add a header to that data in

order to accomplish layer 4's goals of

service to Service delivery

then layer 4 is going to hand that to

layer 3 and layer 3 is going to add its

own header in order to accomplish the

goal of layer 3 of end to end delivery

and then layer 3 is going to hand that

to layer 2 and layer 2 will add its own

header in order to accomplish the goals

of hop delivery and finally this

construct over here known as a frame is

then going to be serialized and put on

the wire and sent to the other side now

if any of that was unfamiliar to you

specifically the terms hop to hop end to

end and service to service I'd recommend

checking out my videos on the OSI model

I promise it'll be one of the best takes

on the OSI model you've ever seen in any

case going back to this comparison Point

what is meant by a more overhead and

less overhead has to do with the size of

the header being added to the data TCP

is going to add a larger header to the

data compared to UDP let me show you

here is what a UDP header would look

like notice the UDP header only includes

four Fields a source port and a

destination port to accomplish the goal

of service to Service delivery a length

which indicates to the other side how

long the entire segment is and finally a

checksum and in the case of UDP this

checksum is optional

notice the entire thing is only eight

bytes

by comparison the TCP header looks like

this notice it is much larger it's

actually 20 bytes at minimum and

sometimes can be larger if options are

included with options the TCP header can

be at most 60 bytes

either way you can see that it's adding

a lot more information to each data

payload well that kind of makes sense

because TCP has more features and to

accomplish these features TCP has to add

more information to the data

TCP also has a source and destination

Port just like UDP TCP doesn't have a

length per se but it does have an offset

which indicates how long the TCP header

is and TCP has a checksum but in the

case of TCP it's actually mandatory

otherwise all of these fields over here

are all new in TCP and don't actually

exist in UDP

these are the fields which accomplish

these features of TCP you're going to be

looking at a lot of these fields in more

detail in the next lesson

for now I just want to really drive home

the point of what is meant by more

overhead versus less overhead with TCP

versus UDP

so that takes care of illustrating the

core attributes of TCP and UDP

next I'd like to discuss and even dispel

a few myths about TCP and UDP there are

four myths that we're going to be

talking through and I'll say at the

outset of this that some of these might

just be subjective aversions to certain

phrases

either way I do want you to be able to

speak to TCP and UDP smartly so with

that said let's talk about the first

myth that we're going to dispel and that

is that UDP is faster this is not true

the speed is actually identical

now I'm guessing what people mean when

they say UDP is faster is that UDP has

less overhead than TCP if that's what

they mean then they should use the term

less overhead saying UDP is faster

implies that a packet sent via UDP will

get to the other side faster than a

packet sent by TCP

the term for how long it takes a packet

to get across to the other host is known

as leads and the latency is actually

completely unaffected whether you're

using TCP or UDP

so the term UDP is faster is not

actually true

yes UDP provides less overhide than TCP

but you can't actually say a UDP packet

is faster and will get to the other side

any quicker than a TCP map

so that is the first myth that I wanted

to spell

the second myth is this guy TCP is more

secure and if I can be honest with you

this is by far the myth that I dislike

the most

as someone who teaches security and

cryptography and SSL and TLS and people

say TCP is more secure it really makes

my blood Bowl TCP is not more secure the

security of both is identical in fact

you can say that either protocol is

equally insecure since neither protocol

provides any sort of security to data

packets that are sent onto the wire

if you actually want security applied to

your data packet you're going to have to

apply them in another layer you'll have

to use something like ipsec at layer 3

or SSL TLS or SSH at layer 5 through 7.

but at layer 4 the choice of TCP and UDP

is equal security or rather equally

insecure

so the myth that TCP is more secure is

completely untrue

anybody that says otherwise is wrong

that is the second myth that I wanted to

spell for you

the third myth is this one UDP is

unreliable that's also not true

but for this one I actually have some

sympathy for it people say that TCP has

reliability so wouldn't it make sense to

then say UDP is unreliable

I get it but a better way of saying that

would be something like this

UDP doesn't provide a reliability at

layer 4.

saying it like this tends to give UDP a

bad reputation the odds of a packet

getting through the wire to the other

side are identical whether you're using

TCP or UDP the only difference is TCP

actually provides confirmation of data

delivery whereas UDP does not

UDP in fact allows the application to

provide any sort of reliability that the

application needs it simply doesn't

provide any magically at layer 4 like

TCP does that's a better way of saying

this myth and that is also why I dislike

the phrase UDP is unreliable and is also

why I avoided saying it earlier in this

lesson

which brings us to the fourth myth that

I want to dispel and that is this one

and I'll be honest this one might just

be a syntax issue but one way or another

the myth is TCP provides guaranteed

delivery that is also not true

TCP simply provides informed delivery in

the sense that TCP provides confirmation

of data delivery

but TCP cannot guarantee that delivery

of packets will get to the other side

if something is wrong with the wire

Between Two Hosts whether you put a TCP

packet on the wire or a UDP packet on

The Wire the odds of it getting through

or not getting through are identical so

TCP can't actually guarantee that

anything is actually going to be

delivered all TCP is going to do is

provide reliability in the sense of we

know when data is delivered and

therefore we know when data is not

delivered TCP cannot magically make data

arrive that's why I dislike this phrase

of TCP is a guaranteed delivery but

again that could just be a phrase that I

personally am not a big fan of

either way those are the four myths that

I wanted to talk through in this video

and that in fact wraps up the main

things I wanted to cover in this lesson

in the next lesson we're going to unpack

exactly how TCP provides all these cool

features we just got done illustrating

and if you understood all the things you

went through in this lesson and you'll

follow along with everything we're going

to go through in the next lesson then

you can safely say that you understand

TCP better than most but even then these

first two lessons are really only

scratching the surface with TCP

there is so much more to TCP that we

could be discussing for instance we

could talk through different flags we

could talk through the sliding window we

could talk through how the checksums are

actually calculated we could discuss the

different flow control algorithms like

TCP Reno and TCP Tahoe we could talk

through ecn and cwr and various TCP

options some of which exist in pretty

much every single TCP connection of the

modern era and I am absolutely willing

to take the time to create the videos

teaching through each of these

additional items but if I'm going to do

that I need you to do me a favor

I put a lot of time and effort into the

content I produce my goal is to always

create the best possible training

content for you but unfortunately that

means I can't really keep up with a

YouTube weekly delivery schedule which

means regrettably my content will never

be favored by the YouTube algorithm

so if you want me to continue making

this TCP series I need you to help me

blow up these first two videos

do the usual like comment and subscribe

but also share links to this amongst

your peers or post it on Twitter

LinkedIn or Reddit or whatever social

media platform you prefer if these two

videos get a wide following then I'll

happily create content covering the rest

of these concepts for you

with that said we bring this lesson to a

close the main takeaways from this

lesson are understanding the four major

differences between TCP and UDP and what

is actually meant by each of them and

also understanding the four myths we

dispelled and why each of them might be

wrong

in the next lesson we're going to go

further with TCP and I'll show you how

TCP actually provides each of these

features

but that's it for this lesson I hope you

enjoyed this video thank you for

watching and I'll see you in the next

one

thank you

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foreign

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