During the initial installation of your network interface card driver your
upper layer protocols like IP or IPX/SPX was binded to a frame type of your
choice , in your case either IEEE 802.3 or Ethernet II. So the packet will
be encapsulated with the frame type of your choice.
-----Original Message-----
From: Billy Monroe <[EMAIL PROTECTED]>
Newsgroups: groupstudy.cisco
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Sunday, February 04, 2001 9:27 PM
Subject: Re: Clarify the differences between Ethernet & IEEE 802.3
>Thanks.
>I mean, during encapsulation how IEEE 802.3 or Ethernet will be selected ?
>"Who" decides that ?
>
>
>"Curtis Call" <[EMAIL PROTECTED]> wrote in message
>4.3.2.7.0.20010204110556.00ab6100@mail">news:4.3.2.7.0.20010204110556.00ab6100@mail...
>> They are different standards for ethernet. They both use CSMA/CD. 802.3
>> was defined by the IEEE and Ethernet was defined by Xerox I believe.
>>
>> The difference is in the packet format:
>>
>> Ethernet:
>> Destination Address (6 octets) - Source Address (6) - Protocol (2) - Data
>> (Variable) - FCS (4)
>>
>> 802.3
>> Destination Address (6 octets) - Source Address (6) - Length (2) - Data
>> (Variable) - FCS (4)
>>
>> A node can tell the difference between the two protocols because the
>Length
>> of a packet can never be more than 1518 bytes so if that value is more
>than
>> 1518 the node can tell that it is an Ethernet packet and that that
>> particular spot is the protocol type field not the length.
>>
>> Given that 802.3 packets don't contain the protocol type field they
cannot
>> transport different network layer protocols without using additional
>> information which is why 802.2 and SNAP was defined. The 802.2 or SNAP
>> fields occur at the beginning of the Data portion of the packet and are
>> used to specify which protocol is sending the packet.
>>
>> Did that answer your question?
>>
>> At 09:43 AM 2/4/01 -0800, you wrote:
>> >I see a description of the differences between them but I can't really
>> >understand that in practical terms.
>> >Is the IEEE 802.3 the CSMA/CD ?
>> >
>> >
>> >
>> >
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>> FAQ, list archives, and subscription info:
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>
>
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