Hello Mohamed,
Thank you very much for your generous rating - I appreciate it very much!
Now, what is the correlation between a Unique BID for every vlan and the extended VLAN range from 1025 - 4096
when the Extended System ID is used.
No special correlation, or better said, the same correlation as the correlation between the VLAN IDs in the range from 1 to 1024 and the unique BID. The VLAN ID is simply stored in the lowest 12 bits of the former priority field that can hold all VLAN IDs in the range of 0-4095. This is what I perceive as being misleading in the documentation to the Cat4500 you have referenced - it makes the extended VLAN range something special with regards to the complete BID.
I am stating that no VLAN ID is handled specially with respect to the BID even when extended system ID is used. The reserved 12 bits are available to store any VLAN ID in the allowed range 0-4095. With the same priority and the same MAC, various values in the 12-bit field indeed generate a unique BID that is different for each VLAN although the 4-bit priority field and the MAC address stay the same.
Does all this make sense? Please continue the discussion if possible!
Best regards,
Peter
