ISL v. dot1q trunking

[7rbowenii]

Does anyone have information regarding the differences between dot1q and ISL trunks? As I understand it, ISL encapsulates the packet with a 32-byte header. This can decrease the scalability of the network. The addition of say 10 vlans over a trunk would increase the packet overhead per link to 320 bytes? Does qot1q only change a flag within a packet? I have looked for some information regarding this, but can't seem to find exactly what I am looking for. Does anyone know what RFC pertains to dot1q? Thanks.

-Bo

[vmiller]

Heres a start:

http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094665.shtml

Some of the biggest differences include per vlan spanning tree versus one spanning tree, the fact tat ISL is proprietary may play in a multi vendor environment.

I can also suggest Cisco Lan Switching by Kennedy Clark Cisco Press

[bbranch]

802.1Q is not covered by any RFC's as it is an IEEE standard. You can download the standard from the IEEE:

http://standards.ieee.org/getieee802/download/802.1Q-1998.pdf