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what is disadvantage of IEEE 802.1Q over ISL?

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??????????

2 REPLIES

Re: what is disadvantage of IEEE 802.1Q over ISL?

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.

HTH

Ankur

Purple

Re: what is disadvantage of IEEE 802.1Q over ISL?

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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