802.3 frames naming conventions ether.

Goal

The difference between the types of framing 3/4.

Frames

There are therefore four types of frames of the ether.

a. Moose Ethernet frame "aka" Ethernet 10

b. framework IEEE 802.3 LLC "aka" Ethernet 802.3

c. IEEE 802.3 with SNAP

d. Eternet 2 "aka" revised IEEE 802.3

I get this what throw me is that every book is calling it something different, I need clarity here with good names for these different frame types. For example (b.) is called IEEE 802.3 LLC, Ethernet 802.3 or something else?

What do you call the 4 types to distinguish the difference between them?

And what does it matter in the preamble? Do I just need to know what size of 8 bytes, or should I understand used signs?

CCIE written prep.

Hello Samuel,.

I get this, whats throwing me is that each book is calling them  something different, I need clarity here with the correct names for  these different frame types. For example is (b.) called IEEE 802.3 LLC,  Ethernet 802.3 or something else?

Well, we will look at individual types and let me grab that from my point of view, not to comment on the options at first.

The original Ethernet 1 frame was the initial implementation of Xerox Ethernet and according to Wikipedia, it has never been commercially deployed. In fact, I have trouble finding any specification on this prehistoric Ethernet format. You shouldn't bother with that much, because this type of frame is completely obsolete.

The second generation of Ethernet, also called Ethernet II, 2 Ethernet or Ethernet DIX, was developed by Xerox in cooperation with the digital and Intel. These three names - Ethernet II, 2 Ethernet and Ethernet 10 refer all the same frame format - one that we are now using:

DstMAC, SrcMAC, EthType, data, FCS.

When TEN approached IEEE with the request to standardize the Ethernet, IEEE taken and made a little twist on the frame format, making it a little closer to HDLC which is a format of popular base at that time frame. What resulted has a skeleton base chassis:

DstMAC, SrcMAC, length, data FCS

Note that the only difference is in the redefinition of the EthType field for the field "length". There was also a change of format in the preamble but that pass for now. This Ethernet IEEE base frame skeleton is standardized in 802.3.

I call the 802.3 a skeleton for a reason. It isn't really a format usable frame because this frame structure is absent of any identification payload. Simply, not sure what is the framework. IEEE obviously did not intend this skeleton 802.3 frame to be used just that clearly, but rather, they reused the HDLC logical link control and they adapted for Ethernet in their standard 802.2. This adaptation of the LLC consisted of adding at least three bytes of the header (flight bytes of the data section because the frame was not allowed to grow bigger): bytes DSAP, PAAS and control. So, when we take the skeleton 802.3 and composed it with the fields 802.2 LLC derived, we get

DstMAC, SrcMAC, length, DSAP, PAAS, control, data, FCS

This format of image in its entirety should be called 802.2 LLC. Note that if you call it 802.3 LLC, you say nothing wrong - you have the basic skeleton 802.3 more the 802.2 LLC. Personally, I like to call it 802.2 LLC, however.

Soon, the limits of this frame format is apparent, as the DSAP/SSAP fields to describe the Protocol within the framework are just 1 byte of length, including half of the values being reserved for private/group dealing with service and the remaining values are too few to describe all protocols with realism of existing top level (not even mention a rigid process to get an official SAP for a protocol value). Therefore, IEEE came with the snap-snap-IN image format that retains the basic structure of the 802.2 LLC, but steals another 5 bytes of the data field for the Protocol provider number YES and Protocol. The entire frame would then become

DstMAC, SrcMAC, length, DSAP, PAAS, control, YES, ProtoID, data, FCS

Curiously, this component extension snap-in is described in the document 802 Basic (no matter what 802.x additive). Therefore, this format of frame must be called simply SNAP 802.

So to summarize:

DstMAC, SrcMAC, EthType, FCS data: Ethernet II, Ethernet 10 Ethernet 2

DstMAC, SrcMAC, length, data FCS: IEEE 802.3 (not really usable, just a basic container)

DstMAC, SrcMAC, length, DSAP, PAAS, control, data, FCS: IEEE 802.3 AND IEEE 802.2 LLC

DstMAC, SrcMAC, length, DSAP, PAAS, control, YES, ProtoID, data, FCS: IEE 802 SNAP

And how important in the preamble field? Do I just need to know that  it's 8 bytes in size, or do I need to understand the signalling used?

There are more important things on the R & S of CCIE written that the preamble of Ethernet, but just in case:

10 = 802.3 preamble preamble + 802.3 start Frame delimiter

Preamble: 7 bytes of 10101010 binary (0xAA or 170)

Delimiter of start-of-Frame = 1 byte of binary 10101011 (0xAB 171 or)

IEEE comes officially divided the 8 b 10 terrainpour 7 b preamble they call preamble and 1 b called SOF field.

Welcome to ask for more!

Best regards

Peter

Tags: Cisco Network

Similar Questions

  • Snapshot, Naming Convention

    Is it possible to change the snapshots naming convention?

    Work on a shared storage system uses NTFS on the back end so "/" is a character not consistent therefore generate snapshots fail.

    Not as far as I know. You should certainly file a feature request for this because by default immediately uses the date/time stamp, which really should not use the /.

  • Naming Convention for LabVIEW

    Hello

    What naming convention should be followed in LabVIEW? I will use typical CamelCase (MyNewProgram.vi) or underscore (My_New_Program.vi) or with spaces (my new Program.vi)? In most standard LabVIEW programs, I have observed that different is with spaces (my new Program.vi) but most of the text language programmers prefer without convention spaces. What is the best way to name VI or variable in LabVIEW and what is the reason for this?

    I went through the guidelines and a different post, but they mention just not to use a special character. Nowhere I found the naming convention in LabVIEW.

    Kindly Guide.

    Thank you.

    The case of camel hails from the days of DOS when you were allowed only 8 characters for a file name.  Windows allow spaces in file names.  Linux does not work.  Due to the limitation of Linux/Unix, you will often see text language programmers to use the underscore character.  Almost all my code is on Windows, so I use spaces in the names of my files simply because I find it easier to read than the underscore.

  • VMDK File Naming Conventions

    Hello

    I've attached a screenshot of one of the virtual machine. I need to understand these vmdk naming conventions. Snapshot of this virtual machine was created.

    Thank you

    Mihir

    By default, the hard files have the name of the virtual machine. The first virtual disk is named hard, the second _1.vmdk of ...

    For snapshots, a 6-digit number is appended to the name (e.g. - 000001.vmdk).

    André

  • How to maintain the availability of the data store after the upgrade to ESXi 5.1 with the new IP address and the naming convention?

    How can we maintain access to the presented LUNS and VMFS data store after we improve the ESX in ESXi with the new naming convention and the new model of IP addressing?

    My back-end SAN EMC Clariion is VNX

    Thanks in advance.

    How are the hosts connected to storage systems. With FC HBA for example, there is basically nothing you need to do since the WWN will remain the same and so LUN presentation of the zoning on the switch and storage system does not need to be reconfigured.

    André

  • Naming Convention Document request

    Hello CH team,

    If you can please provide a table with all the codes and naming conventions that we can use in Ps and AI for quick reference.

    Thank you very much.

    Jerry is correct. (x) ! will do a skin of brothers and sisters keyboard trigger. Currently, there is no code for the lock.

    In general we recommend to make the most of the rigging in character animation, because it is easier to see the live results and does not need to memorize codes. That's why you can not do things like sticks in a PSD.

  • The datastore Naming Convention

    Does anyone have a good set of recommendations for a data store naming convention?

    This is why we did it.

    And Yes, it can cause problems if you are replicating, because the name duplicate on the other side

    In this case, you could do arrayIDpair like this:

    DMX-0595_0445-T1-R to say that it is a level 1 to replicate on DMX device between table 0595 and 0445.

  • Group of port and the naming convention for vLAN

    What is the naming convention better for groups of ports on vSwitches?  This naming convention should match how we name them VLAN on the physical switches and how important is that?

    Hi VMinator,

    To answer your question, he has not agreed to 'standard' for names of portgroup.  That's all what you're comfortable with the support and what works for you and your organization.  A bit like server names; Some companies are going hardcore with the naming conventions and others their name after the characters in science fiction or world of warcraft bosses

    Forensic science more you pack in a naming of the control standard more you have (i.e. for scripts, health check, etc. see below).  Also, if the name itself answers questions on his own and allows you to save a phone call that is priceless.  For example - the guys says unix... "Uh which network to choose for my new virtual machine.  My IP is blah blah blah. "Well, with right portgroup name, this question would have answered itself... and maybe even recorded some interruptions of service in other cases by the simple fact of being clear and effective in the communication of how this virtual device should work: purely expressed through an appropriate naming convention.

    Here's another one.  My last concert, we had thousands of virtual machines that had to move data centers and when they landed, they needed to change the IPs and start using 3 vNIC (instead of 1) on each virtual machine.  Each vNIC with a different subnet mask.  All support should be conducted by a team of outsourced with minimum experience of VMware.  The only way to support something like this and be effective is PowerCLI.  With just invited the naming convention only, you can perform various tasks such as query the virtual computer and check its settings of portgroup compared to its actual IP information in the operating system, initiate a ping from .NET to the virtual machine, if there is any questions Act automatically.  Some actions that will have to be performed include, for example, change the portgroup or mask on a set of clients;  Or questioning guests and glean information network (CDP, vSwitch, portgroup of information etc.) and compare observed network vs network expected enumerated in the PG naming convention. etc etc.  The list of actions that you can take are limited only by your creativity.  The naming standards give you effective power both in manual and automatic efforts.

    Still, notice of one man, but every site I care and feeding generally ends with a PG standard similar to what I first described above in my previous post.  Don't forget my example naming convention is Basic.  There are many other attributes that you can add (i.e. in vCloud deployments, in addition to the info network, you can choose to identify various features specific to vCloud org-networks, etc.).

    TBH just most of the companies have appointed VM-network exchanges (ok not bad) or some random shortname which doesn't help troubleshooting.  They are fairly easy to fix and also change over time, if necessary.  You can easily drag and drop a set of virtual machines (although I don't personally do this way) in the new port group (via the page of networking to CTRL + SHIFT + N) or PowerCLI it (Yes!  way to go).  Of course, always the ping tests before and after the change.  There are a lot of scripts out there (or ask master lucd post in PowerCLI VMTN forums).  If this is net-news, then you are ahead of the game and will have a standard to follow, whatever it is.

    Best of luck and have fun!

  • VM naming Convention recommended...

    Dear team,

    I just need your asissatnce on the VM naming convention. Can you please help me with the same best practices.

    concerning

    Mr. VMware

    Yes, you can certainly use the spaces, '-' and '_ '. What you should not use are language specific special characters.

    André

  • names of data files Naming Convention!

    Hello

    My question is maybe stupid, but I'm not sure of the my control/log/dbf file naming convention. I am oracle 11g and asm is configured with active OMF. When I checked the file name, I get filename with certain numbers. What this number means.
    ASMCMD> ls
    EXAMPLE.265.790927371
    ONKAR.267.791219239
    SYSAUX.257.790927221
    SYSTEM.256.790927219
    UNDOTBS1.258.790927221
    USERS.259.790927223
    ASMCMD> 
    Could someone tell me please what these numbers represent? I tried google, but not got reasonable answers.

    -Onkar

    http://docs.Oracle.com/CD/E11882_01/server.112/e18951/asmfiles.htm#i1023283

    First number is the number of folder (not in the database, but in ASM), and as I noticed, the files of 'user' (from ASM instance view) begin 256. 'Progressive', as ASM fichier_parametres and OCR files are less than 256.
    Second number is incarnation, which is derived from the date and time when the file is created.

    These two ensure uniqueness of the names of files in ASM.

  • Naming Convention for user performed at the Complutense University of MADRID

    Hi all

    Are there specific rules for the naming convention for the assignment of user name in the University Complutense of MADRID 11 g? Is there a specific type of some special characters that cannot be used by the UCM in username?

    Thank you
    Saurabh Anand

    It is the same for the user name. This is a limitation of the underlying directory server. So your restrictions will be the result of the restrictions in the underlying system (AD or LDAP). in general, stick with single-byte characters and using something like the first initial and the name or rating first.last is fairly reliable

  • Technical question about the naming conventions used in the API

    What does the prefix 'PF_' rest in all the function names in the SDK of EI?  It is not immediately obvious to me and was just curious.  I would like to have an idea of how the naming conventions came when I learn a new code.

    Thank you!

    Interesting question.  PF stands for package of plug-in filter in After Effects.

  • The physical layer Naming Convention

    Hello

    I am trying to install my physical layer and see the reference to name them correctly. When I look at the examples of sales, I see they use A01, A02, etc..

    But I have others indicate that I should their name:
    fact_sales
    dim_customers

    Anyone has any good advice on how to put in place a naming convention that is appropriate to the physical layer.

    And that I should just using this naming convention in names for the alias tables?

    Thank you
    Kathy

    Use as
    SALES_F and CUSTOMERS_D

    _F made
    _D for Dimensions
    At the top of case

    For Alias, use DATE (W_DAY_D) closing

    Shud be useful

  • naming conventions of schema in the oracle database

    Hello gurus,

    In some workplaces, I saw the names of patterns being called as
    "ABC_ADMIN "
    "ABC"
    "XYZ_ADMIN"
    "XYZ"
    Just curious, is recommended for this naming convention or is this standard practice?

    Any advice is greatly appreciated!

    Thank you

    If the names are significant (that will depend on what are the objects in the different schemas) and the underlying architecture is reasonable, then the naming convention would be a good practice.

    -How the objects in the schema of the CBA relate to objects in the ABC_ADMIN schema?
    -What, exactly, the _ADMIN suffix indicates?

    My unfounded guess, is that you have two related schemas because you create a schema that has objects and another scheme that has limited access to these objects (ideally just through views, procedures and functions) for applications to use to connect. If this is the case, it is not clear to me that ABC and ABC_ADMIN hold the objects in the application of the CBA. But if you are actually separate objects for other reasons, then _ADMIN can give its full meaning.

    Justin

  • Naming Convention for Flash? _mc, instances

    Im a bit bogged down in the denomination in Flash.

    IM pretty new to the clips in the film clips as well as grant shares to the buttons to assign said film clips...

    I've been naming my calendar of video clips, but then I have to put a clip in the clip... I've exhausted the names.

    So going for an instance name makes even more twisted.

    No one cares to share their naming conventions? As you name case or anything action verbs?

    I use the btn, the mc, the format of gs to name things, but it becomes overwhelming for simple actions already, so I guess that there is a better nomenclature...

    Personally I don't like Hungarian notation or notations of postfix. Fix _mc or _array post for example come a hold on before typing data and allowed the ActionScript editor guess that something was class and provide code hinting. Now with the best document you can always get the code hinting without using this notation. I always found it difficult to read and type.

    And that's why I don't like Hungarian notation of mcClip or bBoolean. Find it me difficult to read again.

    I recommend that people find their own conventions and pretty much stick to them. It is a very personal matter of how to find the meaning and order and it's so different for each person.

    I think that part of what you are experiencing is that you have difficulties with the library and naming of instances?

    In the library, I use capital letters and spaces. For instance names, I use camelBackCaseWithNoSpaces.

    Often if I have something nested in the library I have something like:

    Control Panel

    Panel arrow up

    Scroller Control Panel

    that holds together in the library. If I have a lot of assets, I'll do a folder

    Control Panel

    Assets of Control Panel

    Panel arrow up

    etc...

    Then for the instances I would probably call the control panel

    Control Panel

    Or if there are several of them:

    controlPanel0, controlPanel1, etc.

    Don't start ever and with a number of instance and learn to start counting from zero!

    Then, inside, I would give the name of instances as

    up arrow

    scroller

    Are other popular names that I use a lot

    work

    background

    content

    holder

    Does this help?

Maybe you are looking for