Editing Transport layer (section)

==Protocols==
This list shows some protocols that are commonly placed in the transport layers of the [[Internet protocol suite]], the [[OSI protocols|OSI protocol suite]], [[NetWare]]'s [[IPX/SPX]], [[AppleTalk]], and [[Fibre Channel]].

{{Div col|colwidth=30em}}
* ATP, [[AppleTalk|AppleTalk Transaction Protocol]]
* CUDP, [[Cyclic UDP]]<ref>{{citation |url=https://www.cs.cornell.edu/zeno/Papers/cyclicudp.pdf |title=Cyclic-UDP: A Priority-Driven Best-Effort Protocol |author=Brian C. Smith |access-date=2020-02-23}}</ref>
* DCCP, [[Datagram Congestion Control Protocol]]
* FCP, [[Fibre Channel Protocol]]
* IL, [[IL Protocol]]
* MPTCP, [[Multipath TCP]]
* NORM, [[NACK-Oriented Reliable Multicast]]
* [[QUIC]]
* RDP, [[Reliable Data Protocol]]
* RUDP, [[Reliable User Datagram Protocol]]
* SCTP, [[Stream Control Transmission Protocol]]
* SPX, [[IPX/SPX|Sequenced Packet Exchange]]
* SST, [[Structured Stream Transport]]
* TCP, [[Transmission Control Protocol]]
* UDP, [[User Datagram Protocol]]
* [[UDP-Lite]]
* μTP, [[Micro Transport Protocol]]
{{div col end}}

=== <span class="anchor" id="COMPARISON1"></span><span class="anchor" id="Comparison of transport layer protocols"></span>Comparison of Internet transport layer protocols ===
{| class="wikitable" style="text-align:center"
|-
! scope="col" | Feature
! scope="col" | [[User Datagram Protocol|UDP]]
! scope="col" | [[UDP-Lite]]
! scope="col" | [[Transmission Control Protocol|TCP]]
! scope="col" | [[Multipath TCP]]
! scope="col" | [[SCTP]]
! scope="col" | [[DCCP]]
! scope="col" | [[RUDP]]{{efn|RUDP is not officially standardized. There have been no standard-related developments since 1999.}}
|-
| style="text-align:left" | Packet header size
| 8 bytes
| 8 bytes
| 20–60 bytes
| 50–90 bytes
| 12 bytes{{efn|Excluding data chunk headers and overhead chunks. Without embedded chunks, an SCTP packet is essentially useless.}}
| 12 or 16 bytes
| 14+ bytes<!--Including 8-byte UDP header-->
|-
| style="text-align:left" | Typical data-packet overhead
| 8 bytes
| 8 bytes
| 20 bytes
| ?? bytes
| 44–48+ bytes{{efn|Counted as follows: 12 bytes SCTP header + 16 bytes DATA chunk header or 20 bytes I-DATA chunk header + 16+ bytes SACK chunk. Additional non-data chunks (e.g. AUTH) and/or headers for additional data chunks, which might easily increase the overhead with 50 bytes or more, not counted.}}
| 12 or 16 bytes
| 14 bytes
|-
| style="text-align:left" | Transport-layer packet entity
| Datagram
| Datagram
| Segment
| Segment
| Datagram
| Datagram
| Datagram
|-
| style="text-align:left" | Connection-oriented
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| style="text-align:left" | Reliable transport
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{No}}
| {{Yes}}
|-
| style="text-align:left" | Unreliable transport
| {{Yes}}
| {{Yes}}
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| style="text-align:left" | Preserve message boundary
| {{Yes}}
| {{Yes}}
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| style="text-align:left" | Delivery
| Unordered
| Unordered
| Ordered
| Ordered
| Ordered / Unordered
| Unordered
| Unordered
|-
| style="text-align:left" | Data [[checksum]]
| {{Optional}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Optional}}
|-
| style="text-align:left" | Checksum size
| 16 bits
| 16 bits
| 16 bits
| 16 bits
| 32 bits
| 16 bits
| 16 bits
|-
| style="text-align:left" | Partial [[checksum]]
| {{No}}
| {{Yes}}
| {{No}}
| {{No}}
| {{No}}
| {{Yes}}
| {{No}}
|-
| style="text-align:left" | Path [[Maximum transmission unit|MTU]]
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{dunno}}
|-
| style="text-align:left" | [[Flow control (data)|Flow control]]
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{No}}
| {{Yes}}
|-
| style="text-align:left" | [[Congestion control]]
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{dunno}}
|-
| style="text-align:left" | [[Explicit Congestion Notification]]
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{dunno}}
|-
| style="text-align:left" | Multiple [[Stream (computing)|streams]]
| {{No}}
| {{No}}
| {{No}}
| {{No}}
| {{Yes}}
| {{No}}
| {{No}}
|-
| style="text-align:left" | [[Multi-homing]]
| {{No}}
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{No}}
| {{No}}
|-
| style="text-align:left" | Bundling / [[Nagle's algorithm|Nagle]]
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{No}}
| {{dunno}}
|}
{{notelist}}

=== {{Anchor|COMPARISON2}}Comparison of OSI transport protocols ===
ISO/IEC 8073/ITU-T Recommendation X.224, "Information Technology - Open Systems Interconnection - Protocol for providing the connection-mode transport service", defines five classes of connection-mode transport protocols designated class 0 (TP0) to class 4 (TP4).  Class 0 contains no error recovery and was designed for use on network layers that provide error-free connections. Class 4 is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the session layer.  All OSI connection-mode protocol classes provide expedited data and preservation of record boundaries.  Detailed characteristics of the classes are shown in the following table:<ref>{{cite web
| title = ITU-T Recommendation X.224 (11/1995) ISO/IEC 8073
| url = http://www.itu.int/rec/T-REC-X.224-199511-I/en/
| website = Itu.int
| access-date=2017-01-17
}}</ref>

{| class="wikitable"
|-
! scope="col" | Service
! scope="col" | TP0
! scope="col" | TP1
! scope="col" | TP2
! scope="col" | TP3
! scope="col" | TP4
|-
| Connection-oriented network
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| Connectionless network
| {{No}}
| {{No}}
| {{No}}
| {{No}}
| {{Yes}}
|-
| Concatenation and separation
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| Segmentation and reassembly
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| Error recovery
| {{No}}
| {{Yes}}
| {{No}}
| {{Yes}}
| {{Yes}}
|-
| Reinitiate connection (if an excessive number of [[Protocol data unit|PDUs]] are unacknowledged)
| {{No}}
| {{Yes}}
| {{No}}
| {{Yes}}
| {{No}}
|-
| Multiplexing and demultiplexing over a single [[virtual circuit]]
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| Explicit flow control
| {{No}}
| {{No}}
| {{Yes}}
| {{Yes}}
| {{Yes}}
|-
| Retransmission on timeout
| {{No}}
| {{No}}
| {{No}}
| {{No}}
| {{Yes}}
|-
| Reliable Transport Service
| {{No}}
| {{Yes}}
| {{No}}
| {{Yes}}
| {{Yes}}
|}

There is also a connectionless transport protocol, specified by ISO/IEC 8602/ITU-T Recommendation X.234.<ref>{{cite web
| title = ITU-T Recommendation X.234 (07/1994) ISO/IEC 8602
| url = http://www.itu.int/rec/T-REC-X.234-199407-I/en/
| website = Itu.int
| access-date=2017-01-17
}}</ref>