Yes. Thanks. That helps. I have been doing more research and see that
Ethernet II is the one to use in most cases these days.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Priscilla Oppenheimer
Sent: Tuesday, May 29, 2001 2:19 PM
To: [EMAIL PROTECTED]
Subject: Re: Which Ethernet Frame Does Everyone Use [7:6179]
IPv4 and IPv6 use the Ethernet II frame format. Some server and desktop OSs
support changing the frame format to 802.3, although there's no reason to
do this usually. In the past, some OSs defaulted to 802.3. But most
implementations these days use Ethernet II.
If a Cisco IOS router receives IP frames encapsulated in an 802.3 header
from a device, the router sends to that device in 802.3 also. You can't
configure the Ethernet frame format for IP with Cisco IOS. But you can
configure the frame format for ARP. Can you think why?
IP isn't the only thing out there, though! :-)
AppleTalk Phase 2 uses IEEE 802.3 with 802.2 and SNAP.
Novell supports four frame types. This is configurable on Cisco IOS routers
in interface mode with the IPX network command, and it is configurable on
clients and servers, of course.
NetBEUI uses 802.3 with 802.2.
SNA uses 802.3 with 802.2.
DECnet uses Ethernet II.
IS-IS uses 802.3 with 802.2.
The question of why some books say there are 4 frame formats and some say 2
frame formats has to do with orientation (Novell orientation versus IP) and
is really a matter of wording.
The other two frame formats, other than the two you mentioned, are a subset
of IEEE 802.3 and are as follows:
Novell raw
Preamble
Start Frame Delimiter
Destination Address
Source Address
Length
Data (no 802.2)
CRC
Preamble
Start Frame Delimiter
Destination Address
Source Address
Length
802.2
SNAP
Data
CRC
Hope that helps.
Priscilla
At 12:36 AM 5/29/01, Ken Chipps wrote:
>I am confused about which Ethernet frame type everyone uses with TCP/IP
>today. I understand that there are four different types. I see from the
>Cisco website that they talk about only two of these four. The two they
>discuss are called Ethernet and IEEE 802.3. The one Cisco calls Ethernet
has
>the following fields
>
> Preamble
> Destination Address
> Source Address
> Type
> Data
> CRC
>
>The one Cisco calls IEEE 802.3 has
>
> Preamble
> Start Frame Delimiter
> Destination Address
> Source Address
> Length
> Data and 802.2 Header inside the data area as best I can tell
> CRC
>
>Why do they mention these two only? Who uses what?
>FAQ, list archives, and subscription info:
>http://www.groupstudy.com/list/cisco.html
>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
________________________
Priscilla Oppenheimer
http://www.priscilla.com
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