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How does ethernet understand what is the upper layer of a frame? What are the values in Ethernet II field? Ethernet is in data link layer, so the upper layer is network layer.

When processing at physical layer and link layer is completed, I have read that frame data is forwarded towards upper layer protocols for processing according to its Type Field. I am a bit confused by this statement as well.

  • Removed the off-topic request for resources. – Ron Maupin Feb 18 at 2:12
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The values in the Ether Type field tell ethernet to which process to pass the payload of the ethernet frame. Ethernet, itself, has no idea what the network protocol is, or how to read the payload. This allows ethernet to carry any network protocol (IPv4, IPX, IPv6, AppleTalk, etc.).

The Ether Type values are detailed in IEEE 802 Numbers.

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How does the ethernet understands what is the upper layer?

It doesn't (need to).

What are the values in Ethernet II field? Ethernet is in data link layer, so the upper layer is network layer.

Ethernet encompasses the physical and the data link layer. Anything can ride on top of that, even application-layer protocols. The EtherType(?) field indicates the kind of payload an Ethernet frame is carrying. The operating system passes the frame to a registered handler for that EtherType, e.g. 0x0800 goes to the IPv4 stack.

When processing at physical layer and link layer is completed , frame data is forwarded towards upper layer protocols for processing which is shown in Type Field. I am bit confused by this statement as well.

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