Comments on: Frame or Packets – Make Sure You Get It Right!

By: Soft Switching Fails at Scale

Soft Switching Fails at Scale — Sat, 09 Jul 2011 18:32:16 +0000

[...] switching is that you can develop some software on in the hypervisor platform that performs all the frame forwarding. The folks over at Network Heresy have pumped out a number of self-serving and bombastic articles [...]

By: tbourke

tbourke — Tue, 05 Jul 2011 17:16:00 +0000

It’s interesting, I’ve been using frames almost exclusively for about a year now. I only deal in Ethernet switching for the most part, or TCP segments. I hardly ever talk about packets anymore.

Fear of a flat planet.

By: Tharak Abraham

Tharak Abraham — Fri, 21 Aug 2009 08:47:46 +0000

For IPx and Appletalk i wont mind calling a IPx Frame or an Appletalk Frame anologous to the IP Frame term.

But that was new about the IBM SNA framing that you mentioned.
Then its indeed confusing.

Appreciate deeper thoughts like that Gregg !!

By: Greg Ferro

Greg Ferro — Fri, 21 Aug 2009 06:39:52 +0000

It’s a common mistake, some people just never take the time to think through the differences between frame and packets.

It’s really annoying though. Correct terminology is vital in our business, one mistake can leads to a lot of wasted money.

By: Greg Ferro

Greg Ferro — Fri, 21 Aug 2009 06:38:27 +0000

IPX and Appletalk are Layer3 of the IETF model and therefore are packets and move across the network inside Ethernet, ATM, FrameRelay, X25 or SMDS or some other type of frame.

If you want to have an interesting discussion, what about IBM SNA traffic which uses Ethernet as a Network / Layer 3 protocol with a full signalling capability and session management layer. That gets confusing.

By: Tharak

Tharak — Thu, 20 Aug 2009 14:32:53 +0000

IMHO, the usage of IP Frame can be compromised if you think that the frame carries IP protocol.

What if it was IPx or Appletalk ?

By: Greg Ferro

Greg Ferro — Sat, 08 Aug 2009 11:01:00 +0000

Yeah. At that point in time, the whle networking industry wasn’t very stable, and the ITU/IEEE hadn’t stabilised their debates. Because the OSI standard used the concept of a Protocol Data Unit (PDU) to encompass anything that was a modular data segment, it took a few more years for frames/packets to stabilise into what we use today.

I think its important to the use the same buzzwords when we communicate, that why it is accepted practice to use frames at L2, packets at L3. Even modern OSI definitions for IS-IS now use this convention.

By: Pavel Stefanov

Pavel Stefanov — Fri, 07 Aug 2009 19:17:38 +0000

Greg, your post reminds me of a recent interview I went to where I was filling in some basic test and corrected a couple of their questions with terms like IP Frame and Ethernet packet. When I was being interview by the guy that wrote the test the next day, he kept on saying “Ethernet packet”.

By: Marko Milivojevic

Marko Milivojevic — Fri, 07 Aug 2009 14:34:52 +0000

Interesting to bring that up… According to general understanding of OSI (I haven’t read actual documents, just books referring to it), L3 packet is carried in L2 frame. I.e. L3 PDU’s are considered to be payload part of L2 PDU. We call this process call data encapsulation.

Now, if you look at Figure 3-1 in IEE 802.3-2008 (page 49), frame is actually carried in the packet . Confused, already?

By: Dmitri

Dmitri — Thu, 06 Aug 2009 22:44:31 +0000

He-he, if it all was so simple.

Have a look at the IEEE 802.3as-2006, Page 6 (or clause 3.1.1 in the complete 802.3 which is newer than 2006), and you’ll see that they call “Frame” something between DA and FCS (inclusive both) and “Packet” something between Preamble and Extension (if any), inclusive both – see “Figure 3-1: Packet format”.

By: Marko Milivojevic

Marko Milivojevic — Thu, 06 Aug 2009 21:50:00 +0000

How are MPLS PDU’s called, then? Or, for example PPPoE PDU’s carried in EWS pseudowire over cell-mode MPLS, transported in SDH that has an underlying lambda-switched DWDM? .

OSI model is fine and I agree that people shouldn’t mix frames and packets, but somtims… just sometimes, there is an argument in everything