The default MTU sizes for different network topologies

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Article ID: 314496 - View products that this article applies to.
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Summary

The maximum transfer unit (MTU) specifies the maximum transmission size of an interface. A different MTU value may be specified for each interface that TCP/IP uses. The MTU is usually determined by negotiating with the lower-level driver. However, this value may be overridden.

More information

Each media type has a maximum frame size. The link layer is responsible for discovering this MTU and reporting the MTU to the protocols above the link layer. The protocol stack may query Network Driver Interface Specification (NDIS) drivers for the local MTU. Upper-layer protocols such as TCP use an interface's MTU to optimize packet sizes for each medium.

If a network adapter driver, such as an asynchronous transfer mode (ATM) driver, uses local area network (LAN) emulation mode, the driver may report that its MTU is larger than expected for that media type. For example, the network adapter may emulate Ethernet but report an MTU of 9180 bytes. Windows accepts and uses the MTU size that the adapter reports even when the MTU size exceeds the usual MTU size for a particular media type.

The following table summarizes the default MTU sizes for different network media.
   Network             MTU (bytes)
   -------------------------------
   16 Mbps Token Ring        17914
   4 Mbps Token Ring          4464
   FDDI                       4352
   Ethernet                   1500
   IEEE 802.3/802.2           1492
   PPPoE (WAN Miniport)       1480
   X.25                        576
				

Properties

Article ID: 314496 - Last Review: June 19, 2014 - Revision: 3.0
Applies to
  • Windows Server 2008 R2 Standard
  • Windows Server 2008 R2 Enterprise
  • Windows Server 2008 R2 Datacenter
  • Windows Server 2008 Standard
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  • Microsoft Windows Server 2003 R2 Standard Edition (32-bit x86)
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  • Microsoft Windows Server 2003 R2 Datacenter Edition (32-Bit x86)
  • Microsoft Windows Server 2003 R2 Standard x64 Edition
  • Microsoft Windows Server 2003 R2 Enterprise x64 Edition
  • Microsoft Windows Server 2003 R2 Datacenter x64 Edition
  • Microsoft Windows Server 2003, Standard Edition (32-bit x86)
  • Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
  • Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
  • Microsoft Windows Server 2003, Standard x64 Edition
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  • Microsoft Windows Server 2003, Datacenter x64 Edition
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Keywords: 
kbinfo kbnetwork KB314496

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