what is disadvantage of IEEE 802.1Q over ISL?

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Sep 25th, 2005
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what is disadvantages of dot1Q ...?

cisco switches support both ISL and dot1Q but is there any special case where we can prove ISL is superior than dot1Q??????????

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ankurbhasin Sun, 09/25/2005 - 07:07
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Hi Devang,

There is no advantage of isl over dot1q. Infact ISL increase the size of the frame by 30 bytes which includes 26 byte of header and 4 byte of tailer.

Dot1q just uses 4 bytes of internal tagging which does not affect the size of the frame much.

Also dot1q is open standard so can be used between multivendor switches.



glen.grant Sun, 09/25/2005 - 18:09
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Also ISL is cisco proprietary and you cannot use ISL to connect to other vendors equipment whereas dot1q is the standard.


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