is 802.1q to ISL switching slower than 802.1q to 802.1q?

[hgru]

Hi,

In many configurations I encounter people tend to use 802.1q. However (because this is te default) ISL is still used over the backplane to the MSFC. Would it be better/faster is this was also set to 802.1q? And is it possible to have 802.1q over the backplae to the MSFC?

Thanks for your responses,

Hans

[tsettle]

Hans,

Many use 802.1q because it is IEEE Standard where ISL is Cisco Proprietary. The ISL trunk between the supervisor and msfc is fixed as part of the system architecture and cannot be changed. There is no speed performance difference between the two trunking methods since they are both conducted at wire speed. The difference is in interoperability between different vendor switches and personal design preference. Again, no difference in performance speed.

[hgru]

I understand that there is no speed difference between ISL or 802.1q. But maybe the switching process from ISL to 802.1q or visa versa is slower than ISL to ISL or 802.1q to 802.1q. For example because from ISL to 802.1q needs re-encapsulation and/or fast forwarding is not possible.

Hans