Start frame delimiter: Difference between revisions
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[[File:ethernet frame.svg|thumb|right|400px|An Ethernet frame inside an Ethernet packet, with SFD marking the end of the packet preamble and indicating the beginning of the frame.<ref name="802.3-2012" />]] |
[[File:ethernet frame.svg|thumb|right|400px|An Ethernet frame inside an Ethernet packet, with SFD marking the end of the packet preamble and indicating the beginning of the frame.<ref name="802.3-2012" />]] |
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The '''Start Frame Delimiter''' ('''SFD''') is the 8-bit (1-byte) value marking the end of the [[Preamble (communication)|preamble]] |
The '''Start Frame Delimiter''' ('''SFD''') is the 8-bit (1-byte) value marking the end of the [[Preamble (communication)|preamble]] and indicating the beginning of the [[Ethernet frame]]. The SFD is immediately followed by the destination [[MAC address]], which is the first field in an Ethernet frame. SFD has the value of 171 (10101011 in binary notation).<ref name="802.3-2012">{{Cite web |
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| url = http://standards.ieee.org/findstds/standard/802.3-2012.html |
| url = http://standards.ieee.org/findstds/standard/802.3-2012.html |
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| title = 802.3-2012 - IEEE Standard for Ethernet |
| title = 802.3-2012 - IEEE Standard for Ethernet |
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Revision as of 21:21, 23 February 2014
The Start Frame Delimiter (SFD) is the 8-bit (1-byte) value marking the end of the preamble and indicating the beginning of the Ethernet frame. The SFD is immediately followed by the destination MAC address, which is the first field in an Ethernet frame. SFD has the value of 171 (10101011 in binary notation).[1]: sections 3.1.1 and 3.2
The preamble of an Ethernet packet consists of a 56-bit (7-byte) pattern of alternating 1 and 0 bits, which allows devices on the network to easily detect a new incoming frame. The SFD is designed to break this pattern and signal the start of the actual frame.[1]: section 4.2.5
See also
References
- ^ a b c "802.3-2012 - IEEE Standard for Ethernet" (PDF). ieee.org. IEEE Standards Association. 2012-12-28. Retrieved 2014-02-08.