ISL vs dot1q

"ISL" is Cisco's proprietary tagging protocol but "dot1q" is an open standard tagging protocol. So Cisco switches can use dot1q and ISL as protocols but other devices can only use dot1q and it is not possible to use dot1q protocol on other brands.

The next difference is the method of tagging between these protocols. in the ISL method, the system adds an "ISL header" and a "New FCS" to the packet.

But in IEEE 802.1Q or dot1q system add a header between TYPE and SRC-MAC and it does not need to add "NEW FCS" to the packet.

So the length of the packet in dot1q is shorter than ISL and data can transfer faster in dot1q.?#cisco?#dot1q?#ISL?#data