Editing Maximum transmission unit (section)

===MTUs for common media===
In the context of [[Internet Protocol]], MTU refers to the maximum size of an [[IP packet (disambiguation)|IP packet]]<!--intentional link to disambig, could be either IPv4 or IPv6 packet--> that can be transmitted without fragmentation over a given medium. The size of an IP packet includes IP headers but excludes headers from the link layer. In the case of an [[Ethernet frame]] this adds a [[protocol overhead]] of 18 bytes, or 22 bytes with an [[IEEE 802.1Q]] tag for VLAN tagging or [[class of service]].

The MTU should not be confused with the minimum datagram size (in one piece or in fragments) that all hosts must be prepared to accept. This is 576 bytes for [[IPv4]]{{Ref RFC|791|rp=24}} and 1280 bytes for [[IPv6]].{{Ref RFC|8200|rp=25}}

{| class="wikitable sortable"
|-
! Media for IP transport
! Maximum transmission unit (bytes)
! Notes
|-
| [[Internet]] IPv4 path MTU
| At least 68,{{Ref RFC|791|rp=24}} max of 64&nbsp;KiB{{Ref RFC|791|rp=12}}
| Systems may use [[Path MTU Discovery]]{{Ref RFC|1191}} to find the actual path MTU. Routing from larger MTU to smaller MTU causes [[IP fragmentation]].
|-
| [[Internet]] IPv6 path MTU
| At least 1280,{{Ref RFC|8200}} max of 64&nbsp;KiB, but optional [[jumbogram]]s go up to 4&nbsp;GiB{{Ref RFC|2675}}
| Systems should use Path MTU Discovery{{Ref RFC|8200}} to find the actual path MTU, unless the minimum MTU (1280 bytes) is not exceeded.{{Break}}Jumbograms are packets with a [[IPv6 header#Hop-by-hop options and destination options|Jumbo Payload option]] to allow transmission of payloads between 65,536 and 4,294,967,295 octets in length.
|-
| [[X.25]]
| Minimal 576 (sending) or 1600 (receiving){{Ref RFC|1356}}
|
|-
| [[Ethernet II framing|Ethernet v2]]
| 1500{{Ref RFC|894}}
| Nearly all IP over Ethernet implementations use the [[Ethernet frame#Ethernet II|Ethernet II frame format]].
|-
| Ethernet with [[Logical link control|LLC]] and [[Subnetwork Access Protocol|SNAP]]
| 1492<ref>[[IEEE 802.3]]{{page needed|date=January 2019}}</ref>
|
|-
|-
| Ethernet [[jumbo frame]]s
| 1501–9202<ref>{{citation |url=http://www.networkworld.com/community/blog/jumbo-frames |title=Jumbo Frames |author=Scott Hogg |date=2013-03-06 |access-date=2013-08-05 |publisher=[[Network World]] |quote=Most network devices support a jumbo frame size of 9216 bytes.}}</ref> or more<ref>{{citation |url=https://www.juniper.net/documentation/en_US/junos/topics/topic-map/physical-interface-properties.html#id-physical-interface-damping-overview|title=Physical Interface Properties |author=Juniper Networks |date=2020-03-23 |access-date=2020-05-01}}</ref>
| The limit varies by vendor. For correct interoperation, frames should be no larger than the maximum frame size supported by any device on the [[network segment]].<ref>{{Cite web
 | url = https://www.stsauver.com/~joe/jumbos/jumbo-frames.pdf
 | title = Practical Issues Associated With 9K MTUs
 | quote = you still need to insure that ALL upstream Ethernet switches, including any switches in your campus core, are ALSO jumbo frame capable
 | date = 2003-02-04 | access-date = 2016-12-15
 | author = Joe St Sauver | publisher = uoregon.edu
 | page = 67
}}</ref>
|-
| [[Point-to-point protocol over Ethernet|PPPoE v2]]
| 1492{{Ref RFC|2516}}
| Ethernet II MTU (1500) less PPPoE header (8); extensions exist
|-
| [[DS-Lite]] over PPPoE
| 1452
| Ethernet II MTU (1500) less PPPoE header (8) and IPv6 header (40)
|-
| PPPoE jumbo frames
| 1493–9190 or more{{Ref RFC|4638}}
| Ethernet Jumbo Frame MTU (1501–9198) less PPPoE header (8)
|-
| [[IEEE 802.11]] Wi-Fi (WLAN)
| 2304<ref>802.11-2012, page 413, section 8.3.2.1; page 381 "The Frame Body field is of variable size. The maximum frame body size is determined by the maximum MSDU size (2304 octets), plus the length of the Mesh Control field (6, 12, or 18 octets) if present, the maximum unencrypted MMPDU size excluding the MAC header and FCS (2304 octets) or the maximum A-MSDU size (3839 or 7935 octets, depending upon the STA’s capability), plus any overhead from security encapsulation."</ref>
|The maximum MSDU size is 2304 before encryption. WEP will add 8 bytes, WPA-TKIP 20 bytes, and WPA2-CCMP 16 bytes. See also [[Frame aggregation]] mechanisms in 802.11n.
|- 
| [[IEEE 802.5|Token Ring (802.5)]]
| 4464
|
|-
| [[FDDI]]
| 4352{{Ref RFC|1191}}
|
|}