802.2 vs. 802.3

chmars53

Can someone please explain - all the books say that 802.3 ='ethernet' when talking about networks. However, 802.2 is stated to be the default for Netware 4.x & higher, and has the LLC field, which would seem (though can't confirm yet) to be the reason multiple browser windows get the correct information.

Sure, 802.3 sets out the architectures (10Base2, 100BaseVG, 10Broad36, etc), and connectors, segment specs (length, # of nodes, etc), so it has 'everything else'.

However, the 802.3 was the original Netware version, and lacks the LLC field - so why is it the 'standard'?? :

"Course Technology ILT" (a course I took last year) book downplays 802.3 with only 1 paragraph, while 802.2 is a page long. In fact it says 802.3 only supports early IPX/SPX versions.

Webmaster

Creepy... I was just doing some background research on this minutes ago... for our soon to be released Network+ - Netware OS and Protocols TechNote.

I'm still not exactly sure what your question is, and I'm sure it's more detailed than you need to know for the Network+ exam. But...

However, 802.2 is stated to be the default for Netware 4.x & higher,

802.2 is the default frame type for Netware 3.12 and 4.x, 802.3 is used for Netware 3.11 and earlier.

and has the LLC field, which would seem (though can't confirm yet) to be the reason multiple browser windows get the correct information.

LLC is not responsible for that... read our OSI model TechNote for more info about LLC. IPX uses the concept of sockets, similar to TCP/IP sockets, to allow multiple processes to communicate over the same link. A socket is a 16-bit number which is appended to the source and destination address in an IPX datagram.

In the context of IPX frametypes, 802.3 and 802.2 do not refer directly to physical architectures, merely to the format of the layer 2 Ethernet frame, in which the IPX packet is encapsulated.
Novell's 802.3 is Novell's Ethernet specification (actually named Novell 802.3 raw) A couple of years later IEEE came with its Ethernet specifcation which is IEEE 802.3 (which is a bit like Novell 802.3 raw + 802.2 LLC) So, 802.3 is Ethernet, 802.2 is LLC.

I hope this helps,

Johan

chmars53

Yes, much of your reply was in the books I read, and I just reviewed your OSI Technote. I have never found any comment yet saying that IEEE 802.3 is like having .2 & .3 combined. It makes sense, but no book said it.

Clearly there must be another source so I can get this straight. I believe what you say because it is in my books too. It made no sense that the book stated about 802.3 "It supports only the IPX/SPX protocol" except that though they may have started on the spec for this first, they finished what became 802.2 first, hence the numbering system. (recalling that I was told 802.11a is faster than 802.11b)

Maybe I will have to go read the spec at an IEEE site. While I can accept some things and just memorize for a test, contradictory information really bothers me, as does anything I have problems with (like getting SAMBA/NFS to work in Linux/Windows linkup; that took awhile, but I got it, even though I should have let it go. MAN pages & 'Linux Bible" are great sources).

Know a good IEEE site adress?

Sorry about the 'creepy' - I do that sort of thing a lot.

Mars

Webmaster

I have never found any comment yet saying that IEEE 802.3 is like having .2 & .3 combined. It makes sense, but no book said it.

That's not exactly what I said... I also mentioned 'a bit', I just said that for "illustration purposes".

There are four major frame types in this context:

- Ethernet_II (Ethernet version 2, released in 1982 by DIX, replacing Ethernet version 1. Uses a typefield (ethertype)in the frame to specify upper layer protocol)
- Ethernet_802.3 (Novell 802.3 raw frame format, based on Ethernet_II, runs on CSMA/CD, support only IPX/SPX because the type field is replaced by a length field .
- Ethernet_802.2 (IEEE 802.3 frame format, also based on Ethernet_II, adds LLC layer, hence header.)
- Ethernet_SNAP (IEEE 802.3 SNAP frame format, adds SNAP field for backwards compatibility with Ethernet Version 2, SNAP field contains Ethertype info)

It's your choice to take my words for it it's free...
(I don't consider myself an expert on this matter, but I started my networking career with Novel 3.12 9 years ago, I experienced the all to common frame type problem, I had to learn about frame types for my Novell CNA, Networking Essentials exam for MCSE NT 4, and extensively for the CCNA and CCDA exams, while IPX was still a major topic in Cisco exams at that time. I'm also doing extensive research about this for an article I'm writing "History of Networking"... so, I'm not making things up here, nevertheless I could be wrong )

Clearly there must be another source so I can get this straight. I believe what you say because it is in my books too. It made no sense that the book stated about 802.3 "It supports only the IPX/SPX protocol"

Actually they are correct, when they are talking about Novell's 802.3 (frame format and frame type). It does only support the IPX/SPX protocol, that is exactly why the IEEE included LLC (defined in 802.2) in their version of 802.3. LLC adds an extra header to the frame which contains 3 fields of which 2 are used to indicate the upper-layer protocol of the source (SSAP field) and the destination (DSAP field).
It think the only reason that Novell decided to call the frame type, that needs to be configured to use the frame format IEEE 802.3, 802.2 to indicate it uses LLC (which their own 802.3 spec does not) and because they created their own frame format Novell 802.3 raw which they named 802.3 already (frame type)...

www.standards.ieee.org
http://standards.ieee.org/getieee802

Another good place to find out more about this is www.cisco.com but you can also try www.novell.com to try and get the history from their perspective and other details about the frame types, since it is really Novell we're talking about.
But again, this is way beyond the scope of the Network+ exam, and you will have to go trough a lot of trouble to find just 1 corporation that still uses 3.11 or earlier, neither 3.12 as a matter of fact, since Netware became millenium proof with version 3.2....

Johan

chmars53

Johan, please don't mistake my questioning with not believing your word; When faced with contradictory information, it can take a while for the right stuff to sink in.

The problem seems to be that you say "Novell 802.3" but the book is supposedly talking only "IEEE 802.3", so I hope you can see my confusion.

In fact, you have MORE qualifications than the people writing the books I am reading - Mike Meyers is only A+ Net+ MCP, and clearly has made mistakes in his books (like the sound card looking for frequencies with an A/D converter instead of voltage levels - for freq. you use filters and pulse counters for specified time, or analyze an input stream recording with SW).

You are right - I am probably trying to get more-detailed information than I need - but with there being things on the A+ tests not covered in 3 books, I am erring on the side of caution.

I will study your response, and hope to soon understand this as well as you.

Thanks for the help,
Mars