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Home > Archive > CCNA > October 2001 > IP TAGGING and FRAME TAGGING
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IP TAGGING and FRAME TAGGING
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| ahpama 2001-10-02, 11:18 am |
| Hi guys,
I am happy because I am applying my knowledge in CCNA study in a real world scenario. 
We will be setting a netscreen firewall in our network and netscreen firewall doesn't support IP tagging. I just like to ask what is the main difference between IP tagging and MAin Tagging?or when is frame tagging a frame tagging and when is IP tagging an IP tagging?
Need help.
thanks a lot. | |
| dmaftei 2001-10-02, 6:09 pm |
| quote:
Originally posted by ahpama
when is frame tagging a frame tagging and when is IP tagging an IP tagging?
Frame tagging is a frame tagging when a frame is tagged, and IP tagging is an IP tagging when an IP packet is tagged.
Seriously, I doubt you will apply any CCNA knowledge to IP tagging. AFAIK IP tagging has to do with MPLS, ATM networks and such, and it's used (or poposed to be used, because it's a very new technology) to improve IP routing performance.
As for frame tagging, it's defined in two IEEE standards, 802.1p and 802.1q. To the best of my knowledge, 802.1p has to do with prioritizing frames, while 802.1q is used VLAN identification.
What's "MAin Tagging"?! Is it a typo, or something I never heard of? | |
| strikeattack 2001-10-02, 7:17 pm |
| 802.1Q is an IEEE standard for identifying frames by inserting a VLAN identifier into the header of the frame. This process uses frame tagging, which modifies the existing frame. This is opposite of frame encapsulation (ISL), in which the original frame is not modified. This format helps to ensure interoperability between switch vendors, because ISL is Cisco Proprietary. This process allows VLANs to work on both Access and trunk links. A frame tagged with 802.1Q adds 4 bytes of overhead, and ISL adds 30 bytes of overhead. This may put the frame over the 1518-byte limit, which may of course cause problems for some switch manufacturers.
802.1Q is sometimes used by Cisco to label an FDDI frame's VLAN association. I suspect that you would use this if you needed to connect a Cisco switch to a non-Cisco switch with a trunk link, but I have always used ISL because it is obviously better practice to stick with one infrastracture vendor. | |
| AndrewH 2001-10-06, 4:13 am |
| Hiya, Is it ISL adds 26 bytes of overhead or 30 bytes?
I don't know much about VLAN. Thanks. |
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