CODEWITHSUNDEEP
network-programmingtcpudpprotocols
Samuel Neff
Samuel Neff

Reputation: 74899

Are there any protocol specifications that allow either TCP or UDP to be utilized?

Are there any networking protocols that are not strictly TCP or UDP but can be used with either one?

For example, HTTP, FTP, STMP, RTMP are always TCP.

DNS, SNMP, DHCP, RIP are always UDP.

Is there anything that can be either TCP or UDP? Or am I wrong in the above assertions?

RTSP is one weird one I know of that uses both, TCP for the control port but UDP for audio/video/quality, but it has strict requirements of what gets sent of each.

I'm asking about standard, published, or at least commonly used protocols, not custom ones.

Upvotes: 4

Views: 860

Answers (5)

Paul Sasik
Paul Sasik

Reputation: 81429

If you examine a Windows' services file you will see a number of protocols registered for both TCP and UDP. Path: C:\Windows\System32\drivers\etc In fact, most of the listings in the services file use both TCP and UDP protocols.

As far as well known apps that use both, I would think that most chat applications use both. sms-chat definitely does but probably most others.

Edit:

From that file, here's a few of the protocols that can be sent over either TCP or UDP (there are exactly 100 listed protocols that use both in the file, many internal MS protocols):

  • echo
  • discard
  • daytime
  • qotd (Quote of the day)
  • chargen (Character generator)
  • time

Upvotes: 2

Pete Wilson
Pete Wilson

Reputation: 8694

SNMP almost always runs over UDP, but it can and does run over TCP. Theory says that it's a bad idea to do SNMP over an error-correcting transport because because some of the very errors that SNMP intends to detect are masked.

Upvotes: 1

more tension
more tension

Reputation: 3342

SIP can use UDP, TCP or SCTP. Using a reliable transport becomes important in SIP if your messages get to be at all large (i.e., significantly larger than the smallest MTU in between user agents). A good example is shared- or bridged-line appearances, which use a form of presence with XML bodies. The larger the number of SIP clients in the shared-line group, the larger the packets are likely to be, making fragmentation and retransmission an issue.

Upvotes: 2

AngryHacker
AngryHacker

Reputation: 61596

SIP can be either UDP or TCP. However, the reality is that UDP is mostly used for this protocol.

Upvotes: 1

Anomie
Anomie

Reputation: 94794

DNS can use either UDP or TCP; TCP is required when the response data exceeds 512 bytes.

Upvotes: 4

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