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Home > Archive > alt.certification.network-plus > December 2003 > Does HTTP use UDP , TCP, or both?
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| Author |
Does HTTP use UDP , TCP, or both?
|
|
|
| Hi,
Does the HTTP protocol uses UDP, TCP, or both as the transport
protocol?
I have recently read an article that said the HTTP uses UDP. However,
the HTTP rfc on the W3C.org website stated the following:
"On the Internet, HTTP communication generally takes place over TCP/IP
connections."
I also ran a utility that trace the communication of the TCP and UDP
protocol, and the utility showed that HTTP used UDP initially, but
then switches to TCP.
Could someone clearify this for me?
Thanks,
Tommy
| |
| Charles M. Kozierok 2003-11-24, 2:25 pm |
| In article <aa725729.0311241029.729ff0c2@posting.google.com>,
Tommy <Tommy@WebSoftwares.net> wrote:
} Hi,
}
} Does the HTTP protocol uses UDP, TCP, or both as the transport
} protocol?
} I have recently read an article that said the HTTP uses UDP. However,
} the HTTP rfc on the W3C.org website stated the following:
}
} "On the Internet, HTTP communication generally takes place over TCP/IP
} connections."
}
} I also ran a utility that trace the communication of the TCP and UDP
} protocol, and the utility showed that HTTP used UDP initially, but
} then switches to TCP.
}
} Could someone clearify this for me?
HTTP uses TCP. If you saw your browser using UDP initially, it was
probably for a DNS resolution request, which uses UDP. The port numbers
will tell the tale, if you recorded them...?
peace,
-*-
charles
| |
| hootnholler 2003-11-24, 6:25 pm |
| Hey Tommy,
Charles is, of course, correct. Just to try and clear the air up a
little...
TCP is a 'routable protocol'. UDP is not. In a nutshell, this means that
tcp will resend data that is found to be corrupt by the receiving machine,
udp does not.
Soo, http does use both tcp and udp. TCP is the main protocol, for most
work you do, but streaming media, audio, etc.. is udp, since it's a bit
quicker (doesn't do error checking and control).
Just to add, I never realized that dns was udp, but hey, that's what you
love about these newsgroups, learn something new every day. :-)
Hoot
"Tommy" <Tommy@WebSoftwares.net> wrote in message
news:aa725729.0311241029.729ff0c2@posting.google.com...
> Hi,
>
> Does the HTTP protocol uses UDP, TCP, or both as the transport
> protocol?
> I have recently read an article that said the HTTP uses UDP. However,
> the HTTP rfc on the W3C.org website stated the following:
>
> "On the Internet, HTTP communication generally takes place over TCP/IP
> connections."
>
> I also ran a utility that trace the communication of the TCP and UDP
> protocol, and the utility showed that HTTP used UDP initially, but
> then switches to TCP.
>
> Could someone clearify this for me?
>
> Thanks,
> Tommy
| |
| Charles M. Kozierok 2003-11-24, 8:25 pm |
| In article <ddwwb.61557$Vu6.42305@twister.rdc-kc.rr.com>,
hootnholler <nospam@goaway.com> wrote:
} TCP is a 'routable protocol'. UDP is not. In a nutshell, this means that
} tcp will resend data that is found to be corrupt by the receiving machine,
} udp does not.
Well... 
Actually, both TCP and UDP are layer 4, transport protocols. They both
are encapsulated in IP datagrams, which are routable. So in effect both
are routable, but that term is not normally used to describe either.
Routing is a layer 3 concept.
Both TCP and UDP have a checksum that can be used to detect corrupted
data. TCP of course has a lot of other additional features.
} Soo, http does use both tcp and udp. TCP is the main protocol, for most
} work you do, but streaming media, audio, etc.. is udp, since it's a bit
} quicker (doesn't do error checking and control).
HTTP does not use UDP. Streaming media is accomplished using other
protocols.
} Just to add, I never realized that dns was udp, but hey, that's what you
} love about these newsgroups, learn something new every day. :-)
DNS mostly uses UDP but also uses TCP for certain functions, such as
zone transfers.
peace,
-*-
charles
| |
| Steven L Umbach 2003-11-24, 9:24 pm |
| HTTP uses only TCP. UDP is used for dns queries and for a lot of internet media. TCP
is considered reliable while UDP is considered unreliable or connectionless. While
TCP may seem the way to go, it has a lot more overhead than UDP and therefore UDP has
a performance advantage. You can use netstat -an to view the various connections or
listening ports on your computer. See link below for some info in common Windows
ports. --- Steve
http://www.microsoft.com/WINDOWS200...fc_por_simw.asp
"Tommy" <Tommy@WebSoftwares.net> wrote in message
news:aa725729.0311241029.729ff0c2@posting.google.com...
> Hi,
>
> Does the HTTP protocol uses UDP, TCP, or both as the transport
> protocol?
> I have recently read an article that said the HTTP uses UDP. However,
> the HTTP rfc on the W3C.org website stated the following:
>
> "On the Internet, HTTP communication generally takes place over TCP/IP
> connections."
>
> I also ran a utility that trace the communication of the TCP and UDP
> protocol, and the utility showed that HTTP used UDP initially, but
> then switches to TCP.
>
> Could someone clearify this for me?
>
> Thanks,
> Tommy
| |
| FireSword 2003-11-24, 9:24 pm |
| What are you talking about???
Do you have an idea of what is a routable protocol??
TCP and UPD are Layer 4 protocols to start with.
Routing occurs at Layer 3, not at Layer 4.
IP is a routable protocol. And both TCP and UDP are carried by IP packets.
The difference between TCP and UDP is that TCP is "connection oriented",
which means that before sending any data the devices need to "talk" to each
other first and agree on flow control. TCP also guarantees delivery of the
packets. UDP does not establish connections before sending data, and if the
packet fails to reach the destination nothing is done to resend it (at least
not in layer 4). Some UDP applications do some error recovery, but at the
application layer(7).
"hootnholler" <nospam@goaway.com> wrote in message
news:ddwwb.61557$Vu6.42305@twister.rdc-kc.rr.com...
> Hey Tommy,
>
> Charles is, of course, correct. Just to try and clear the air up a
> little...
>
> TCP is a 'routable protocol'. UDP is not. In a nutshell, this means that
> tcp will resend data that is found to be corrupt by the receiving machine,
> udp does not.
>
> Soo, http does use both tcp and udp. TCP is the main protocol, for most
> work you do, but streaming media, audio, etc.. is udp, since it's a bit
> quicker (doesn't do error checking and control).
>
> Just to add, I never realized that dns was udp, but hey, that's what you
> love about these newsgroups, learn something new every day. :-)
>
> Hoot
>
>
> "Tommy" <Tommy@WebSoftwares.net> wrote in message
> news:aa725729.0311241029.729ff0c2@posting.google.com...
>
>
| |
|
| Thanks for the reply.
I have another question based on your comment.
Would the following examples be correct:
1. Accessing http://www.somewebsite.com from the browser. Use both UDP and TCP.
UDP
Browser -----> HTTP -----> convert www.somewebsite.com to 213.186.1.1
TCP
Browser -----> HTTP -----> access 213.186.1.1
2. Accessing http://213.186.1.1 from the browser. Use only TCP.
TCP
Browser -----> HTTP -----> access 213.186.1.1
Thanks,
Tommy
"Steven L Umbach" <n9rouz@nscomcast.net> wrote in message news:<Afywb.97475$Dw6.483922@attbi_s02>...[color=blue]
> HTTP uses only TCP. UDP is used for dns queries and for a lot of internet media. TCP
> is considered reliable while UDP is considered unreliable or connectionless. While
> TCP may seem the way to go, it has a lot more overhead than UDP and therefore UDP has
> a performance advantage. You can use netstat -an to view the various connections or
> listening ports on your computer. See link below for some info in common Windows
> ports. --- Steve
>
> http://www.microsoft.com/WINDOWS200...fc_por_simw.asp
>
> "Tommy" <Tommy@WebSoftwares.net> wrote in message
> news:aa725729.0311241029.729ff0c2@posting.google.com...
| |
| FireSword 2003-11-25, 9:24 am |
| Tommy,
Do not confuse DNS with HTTP, those are two different application protocols.
If you wnat to reach a WebSite, the brower needs an IP Address; because all
you know is the name, the browser needs to use DNS to find the Address
BEFORE using HTTP.
DNS uses UDP port 53, HTTP uses TCP port 80.
Your diagram would be like this:
1. Accessing http://www.somewebsite.com from the browser. Use both UDP and
TCP.
UDP
Browser -----> DNS -----> convert www.somewebsite.com to 213.186.1.1
TCP
Browser -----> HTTP -----> access 213.186.1.1
2. Accessing http://213.186.1.1 from the browser. Use only TCP.
TCP
Browser -----> HTTP -----> access 213.186.1.1
"Tommy" <Tommy@WebSoftwares.net> wrote in message
news:aa725729.0311250439.4fe55384@posting.google.com...
> Thanks for the reply.
>
> I have another question based on your comment.
>
> Would the following examples be correct:
>
> 1. Accessing http://www.somewebsite.com from the browser. Use both UDP and
TCP.
>
> UDP
> Browser -----> HTTP -----> convert www.somewebsite.com to 213.186.1.1
>
> TCP
> Browser -----> HTTP -----> access 213.186.1.1
>
> 2. Accessing http://213.186.1.1 from the browser. Use only TCP.
>
> TCP
> Browser -----> HTTP -----> access 213.186.1.1
>
> Thanks,
> Tommy
>
> "Steven L Umbach" <n9rouz@nscomcast.net> wrote in message
news:<Afywb.97475$Dw6.483922@attbi_s02>...[color=blue]
internet media. TCP[color=blue]
connectionless. While[color=blue]
therefore UDP has[color=blue]
connections or[color=blue]
common Windows[color=blue]
http://www.microsoft.com/WINDOWS200...fc_por_simw.asp[color=blue]
| |
|
| Thanks. Now the picture becomes more clear.
From other Google groups, I have read that HTTP uses UDP when
downloading streaming data? Is that correct?
Thanks,
Tommy
"FireSword" <joxel-spamguard-@hotmail.com> wrote in message news:<1069766959.355466@r02.usenetserver.com>...[color=blue]
> Tommy,
> Do not confuse DNS with HTTP, those are two different application protocols.
> If you wnat to reach a WebSite, the brower needs an IP Address; because all
> you know is the name, the browser needs to use DNS to find the Address
> BEFORE using HTTP.
> DNS uses UDP port 53, HTTP uses TCP port 80.
>
> Your diagram would be like this:
>
> 1. Accessing http://www.somewebsite.com from the browser. Use both UDP and
> TCP.
>
> UDP
> Browser -----> DNS -----> convert www.somewebsite.com to 213.186.1.1
>
> TCP
> Browser -----> HTTP -----> access 213.186.1.1
>
> 2. Accessing http://213.186.1.1 from the browser. Use only TCP.
>
> TCP
> Browser -----> HTTP -----> access 213.186.1.1
>
>
>
> "Tommy" <Tommy@WebSoftwares.net> wrote in message
> news:aa725729.0311250439.4fe55384@posting.google.com...
> TCP.
> news:<Afywb.97475$Dw6.483922@attbi_s02>...
> internet media. TCP
> connectionless. While
> therefore UDP has
> connections or
> common Windows
> http://www.microsoft.com/WINDOWS200...fc_por_simw.asp
| |
| FireSword 2003-11-25, 3:25 pm |
| No, HTTP serves only as the means to start a video stream using a hyperlink,
but the streaming itself is using another protocol.
This is also true with FTP downloads, you start the download from a link
that was transfered using HTTP, but the link starts the download using the
FTP protocol.
"Tommy" <Tommy@WebSoftwares.net> wrote in message
news:aa725729.0311251100.35e642b4@posting.google.com...
> Thanks. Now the picture becomes more clear.
>
> From other Google groups, I have read that HTTP uses UDP when
> downloading streaming data? Is that correct?
>
> Thanks,
> Tommy
>
> "FireSword" <joxel-spamguard-@hotmail.com> wrote in message
news:<1069766959.355466@r02.usenetserver.com>...[color=blue]
protocols.[color=blue]
all[color=blue]
and[color=blue]
213.186.1.1[color=blue]
and[color=blue]
213.186.1.1[color=blue]
http://www.microsoft.com/WINDOWS200...fc_por_simw.asp[color=blue]
transport[color=blue]
However,[color=blue]
TCP/IP[color=blue]
UDP[color=blue]
| |
| Steven L Umbach 2003-11-26, 4:25 pm |
| Hi Tommy. Converting website name to ip address is the name reolution
process that is handled by dns which generally uses UDP on port 53. That has
nothing to do with the HTTP protocol on tcp port 80. If you want to learn
and experience this in more detail then I suggest trying to use the Sygate
or Kerio personal firewall on your computer. I like the way Kerio works
better as far as creating using rules but Sygate has much better logging to
even the packet level. Using either will help in learning tcp/ip.
http://www.robertgraham.com/pubs/firewall-seen.html
"Tommy" <Tommy@WebSoftwares.net> wrote in message
news:aa725729.0311250439.4fe55384@posting.google.com...
> Thanks for the reply.
>
> I have another question based on your comment.
>
> Would the following examples be correct:
>
> 1. Accessing http://www.somewebsite.com from the browser. Use both UDP and
TCP.
>
> UDP
> Browser -----> HTTP -----> convert www.somewebsite.com to 213.186.1.1
>
> TCP
> Browser -----> HTTP -----> access 213.186.1.1
>
> 2. Accessing http://213.186.1.1 from the browser. Use only TCP.
>
> TCP
> Browser -----> HTTP -----> access 213.186.1.1
>
> Thanks,
> Tommy
>
> "Steven L Umbach" <n9rouz@nscomcast.net> wrote in message
news:<Afywb.97475$Dw6.483922@attbi_s02>...[color=blue]
internet media. TCP[color=blue]
connectionless. While[color=blue]
therefore UDP has[color=blue]
connections or[color=blue]
common Windows[color=blue]
http://www.microsoft.com/WINDOWS200...fc_por_simw.asp[color=blue]
| |
| hootnholler 2003-11-27, 1:25 am |
| Gentlemen,
First, an apology to Tommy. I apologize for the misinformation, and can
only thank Charles and Firesword for correcting my mistake. I just started
in the network+ training, and thought I had understood udp, but I can see
now that I am terribly mistaken. I do sincerely apologize for any confusion
caused on my part.
Charles and Firesword, a sincere thank you for redirecting the reply. I did
learn from your posts, and along with Tommy, have a much better
understanding of udp, much more than I had originally professed. It does
make sense that the http protocol would provide the link, and then udp would
be activated. I was just regurgitating my readings, in which they say that
it's not a routable protocol and is used in streaming media. I should have
questioned what I had read.
Hoot
"FireSword" <joxel-spamguard-@hotmail.com> wrote in message
news:1069724399.747106@rh9cache2...
> What are you talking about???
> Do you have an idea of what is a routable protocol??
> TCP and UPD are Layer 4 protocols to start with.
> Routing occurs at Layer 3, not at Layer 4.
> IP is a routable protocol. And both TCP and UDP are carried by IP packets.
> The difference between TCP and UDP is that TCP is "connection oriented",
> which means that before sending any data the devices need to "talk" to
each
> other first and agree on flow control. TCP also guarantees delivery of the
> packets. UDP does not establish connections before sending data, and if
the
> packet fails to reach the destination nothing is done to resend it (at
least
> not in layer 4). Some UDP applications do some error recovery, but at the
> application layer(7).
>
>
> "hootnholler" <nospam@goaway.com> wrote in message
> news:ddwwb.61557$Vu6.42305@twister.rdc-kc.rr.com...
that[color=blue]
machine,[color=blue]
>
>
| |
| ITguy_uk 2003-11-27, 6:24 am |
| Tommy,
Another way to see exactly what is going on at various levels of the
OSI model is to use a packet sniffer. I use the open source software
"ethereal" http://www.ethereal.com/, there is a linux app which has
been ported to windows as well. It lets you view all network traffic
on the host PC and lets you to expand and view all the fields in a
single TCP/IP communication out from the application layer right down
to the data link layer.
Its also very useful for diagnosing more complex networking issues.
"Steven L Umbach" <sumbach55@ameritech.net> wrote in message news:<vZ7xb.5769$aw2.2285413@newssrv26.news.prodigy.com>...[color=blue]
> Hi Tommy. Converting website name to ip address is the name reolution
> process that is handled by dns which generally uses UDP on port 53. That has
> nothing to do with the HTTP protocol on tcp port 80. If you want to learn
> and experience this in more detail then I suggest trying to use the Sygate
> or Kerio personal firewall on your computer. I like the way Kerio works
> better as far as creating using rules but Sygate has much better logging to
> even the packet level. Using either will help in learning tcp/ip.
>
> http://www.robertgraham.com/pubs/firewall-seen.html
>
> "Tommy" <Tommy@WebSoftwares.net> wrote in message
> news:aa725729.0311250439.4fe55384@posting.google.com...
> TCP.
> news:<Afywb.97475$Dw6.483922@attbi_s02>...
> internet media. TCP
> connectionless. While
> therefore UDP has
> connections or
> common Windows
> http://www.microsoft.com/WINDOWS200...fc_por_simw.asp
| |
| qa monkey 2003-12-05, 1:24 am |
| According to Ethereal, HTTP uses TCP.
According to my Network+ book HTTP "uses UDP as a transport protocol"
sigh...
btw using: "Network+ Traing Guide" (Que, Bird/Harwood, ISBN 0-7897-2830-3)
"Tommy" <Tommy@WebSoftwares.net> wrote in message
news:aa725729.0311241029.729ff0c2@posting.google.com...
> Hi,
>
> Does the HTTP protocol uses UDP, TCP, or both as the transport
> protocol?
> I have recently read an article that said the HTTP uses UDP. However,
> the HTTP rfc on the W3C.org website stated the following:
>
> "On the Internet, HTTP communication generally takes place over TCP/IP
> connections."
>
> I also ran a utility that trace the communication of the TCP and UDP
> protocol, and the utility showed that HTTP used UDP initially, but
> then switches to TCP.
>
> Could someone clearify this for me?
>
> Thanks,
> Tommy
| |
| Charles M. Kozierok 2003-12-05, 9:24 am |
| In article <vt06l03igdb055@corp.supernews.com>,
qa monkey <byeaw@hotmail.com> wrote:
} According to Ethereal, HTTP uses TCP.
} According to my Network+ book HTTP "uses UDP as a transport protocol"
Time to get a new Network+ book.
peace,
-*-
charles
| |
| James Atkinson 2003-12-24, 3:24 pm |
|
"Charles M. Kozierok" <ixlu@PCGuide.com> wrote in message
news:bqq2h1$h78$1@reader2.panix.com...
> In article <vt06l03igdb055@corp.supernews.com>,
> qa monkey <byeaw@hotmail.com> wrote:
> } According to Ethereal, HTTP uses TCP.
> } According to my Network+ book HTTP "uses UDP as a transport protocol"
>
> Time to get a new Network+ book.
>
> peace,
>
> -*-
> charles
Network+ from ExamCram2 series makes the same statement (in in table showing
HTTP uses UDP/TCP). Later in the book drops the UDP and says HTTP uses TCP.
It's not the only inconsistency I have found in this book. Similar problems
I found in Sybex book, too.
| |
| Frederic 2003-12-25, 9:24 am |
| http://www.mcse.ms/message108937.html
--
Frederic
MCP, IT Project+, i-Net+, CIWA, A+
member of: CompTIA-ITPRO, HDI, IETF
------------------------------------------------------
http://fredsfastcram.netfirms.com
------------------------------------------------------
"Charles M. Kozierok" <ixlu@PCGuide.com> wrote in message
news:bsd3mm$2lt$1@reader2.panix.com...
> In article <rgmGb.235897$Ec1.8315063@bgtnsc05-news.ops.worldnet.att.net>,
> James Atkinson <James__@yahoo.com> wrote:
> } Network+ from ExamCram2 series makes the same statement (in in table
showing
> } HTTP uses UDP/TCP). Later in the book drops the UDP and says HTTP uses
TCP.
> } It's not the only inconsistency I have found in this book. Similar
problems
> } I found in Sybex book, too.
>
> The only reasonable justification I can come up with for claiming this
> is the fact that well-known port number 80 is reserved for HTTP in both
> TCP and UDP. But that's done with most of the common port numbers; it
> doesn't mean that the protocol actually uses both TCP and UDP.
>
> peace,
>
> -*-
> charles
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