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New Member

Which Ethernet are we using today?

Hi All,

I'm learning about Ethernet now.

So,  i know that at first a group called DIX developed ethernet. Later on  IEEE used it and developed the IEEE802.3 Ethernet Standard, which was  again extedned to IEEE802.3u (FastEthernet), IEEE802.3ab (Gigabit  Ethernet) and then finally IEEE802.3ae (10Gbps). Is my understanding  correct ?

But  some where i read that Ethernet II also exists, from where did Ethernet  II come ? And which one are we using today it's IEEE ethernet or  Ethernet II ?

Please help me in this.

Regards,     
Chandu       

Regards, Chandu
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Cisco Employee

Which Ethernet are we using today?

Hi Chandu,

Ethernet was in fact first developed by Bob Metcalfe, David Boggs and a couple of other great minds in Xerox, Palo Alto. The very first Ethernet was an experimental implementation running on a bus topology, with the data transfer capacity of 2.94 Mbps. Xerox later worked on improving this implementation which resulted into creating a so-called

Xerox Wire that already operated on 10Mbps coax. The frame format used in Xerox Wire drafts was not compatible with today's Ethernet: the NIC addresses were only 32 bits long, the type field was only 8 bits long, there was an additional field called Packet Buffer Dispatch Index that basically allowed to select a queue at the receiving host into which the frame was supposed to be stored, and the CRC was only 16 bit long.

Later, when Bob Metcalfe founded the 3Com company, he persuaded Digital, Intel and Xerox to improve the existing Ethernet implementation and promote it as a standard. The DIX consortium took the existing Xerox implementation and turned it into what we know today as Ethernet II. In fact, DIX has produced two versions of Ethernet: Ethernet v1.0 and Ethernet v2.0, also denoted as Ethernet II, but the differences between these two appear to be rather minima,l at least on the data link layer.

Nonetheless, even though the Ethernet II as produced by DIX is often called a standard, it has no binding power for anyone, and it could still be seen as a proprietary technology of these three companies. Therefore, DIX intentionally approached the IEEE and handed the Ethernet II specification over to them to have it openly standardized. IEEE took the Ethernet II specification but they changed it somewhat, obviously being influenced with HDLC-inspired approach to data link layer operation, and gave rise to IEEE 802.3 Ethernet specification with 802.2 LLC (and later came with 802 SNAP), while formally acknowledging the existence of Ethernet II as well.

So the truth is, Ethernet II was there before IEEE 802.3/802.2, and they all exist. You may be interested in reading the following thread as it is also related to this topic:

https://supportforums.cisco.com/thread/2189048

Also, the Wiki page on Wireshark site about Ethernet has an assortment of links to old Ethernet specifications and different sites documenting its history:

http://wiki.wireshark.org/Ethernet?action=show&redirect=Protocols%2Feth#External_links

Regarding your questions of which Ethernet is more used today - in fact, we use all of them. Ethernet II is the most efficient implementation (the least amount of overhead) and is used for majority of traffic. All IPv4 and IPv6 traffic is carried by Ethernet II frames. 802.3 with 802.2 LLC is used by many ISO OSI and IEEE protocols (such as ES-IS, IS-IS, STP, RSTP, MSTP), and often, vendor proprietary protocols are encapsulated into 802 SNAP frames - think Cisco's CDP, VTP, DTP, PAgP, UDLD and (R)PVST.

Also keep in mind that Ethernet II, 802.3, 802.2 LLC, 802 SNAP - they are all only variations in the frame format but they do not directly imply any particular physical layer, at least not today, as there are many physical layers available today.

Best regards,

Peter

2 REPLIES
Cisco Employee

Which Ethernet are we using today?

Hi Chandu,

Ethernet was in fact first developed by Bob Metcalfe, David Boggs and a couple of other great minds in Xerox, Palo Alto. The very first Ethernet was an experimental implementation running on a bus topology, with the data transfer capacity of 2.94 Mbps. Xerox later worked on improving this implementation which resulted into creating a so-called

Xerox Wire that already operated on 10Mbps coax. The frame format used in Xerox Wire drafts was not compatible with today's Ethernet: the NIC addresses were only 32 bits long, the type field was only 8 bits long, there was an additional field called Packet Buffer Dispatch Index that basically allowed to select a queue at the receiving host into which the frame was supposed to be stored, and the CRC was only 16 bit long.

Later, when Bob Metcalfe founded the 3Com company, he persuaded Digital, Intel and Xerox to improve the existing Ethernet implementation and promote it as a standard. The DIX consortium took the existing Xerox implementation and turned it into what we know today as Ethernet II. In fact, DIX has produced two versions of Ethernet: Ethernet v1.0 and Ethernet v2.0, also denoted as Ethernet II, but the differences between these two appear to be rather minima,l at least on the data link layer.

Nonetheless, even though the Ethernet II as produced by DIX is often called a standard, it has no binding power for anyone, and it could still be seen as a proprietary technology of these three companies. Therefore, DIX intentionally approached the IEEE and handed the Ethernet II specification over to them to have it openly standardized. IEEE took the Ethernet II specification but they changed it somewhat, obviously being influenced with HDLC-inspired approach to data link layer operation, and gave rise to IEEE 802.3 Ethernet specification with 802.2 LLC (and later came with 802 SNAP), while formally acknowledging the existence of Ethernet II as well.

So the truth is, Ethernet II was there before IEEE 802.3/802.2, and they all exist. You may be interested in reading the following thread as it is also related to this topic:

https://supportforums.cisco.com/thread/2189048

Also, the Wiki page on Wireshark site about Ethernet has an assortment of links to old Ethernet specifications and different sites documenting its history:

http://wiki.wireshark.org/Ethernet?action=show&redirect=Protocols%2Feth#External_links

Regarding your questions of which Ethernet is more used today - in fact, we use all of them. Ethernet II is the most efficient implementation (the least amount of overhead) and is used for majority of traffic. All IPv4 and IPv6 traffic is carried by Ethernet II frames. 802.3 with 802.2 LLC is used by many ISO OSI and IEEE protocols (such as ES-IS, IS-IS, STP, RSTP, MSTP), and often, vendor proprietary protocols are encapsulated into 802 SNAP frames - think Cisco's CDP, VTP, DTP, PAgP, UDLD and (R)PVST.

Also keep in mind that Ethernet II, 802.3, 802.2 LLC, 802 SNAP - they are all only variations in the frame format but they do not directly imply any particular physical layer, at least not today, as there are many physical layers available today.

Best regards,

Peter

New Member

Which Ethernet are we using today?

Thank you Peter.

The information was clear cut.

Regards,
Chandu

Regards, Chandu
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